VISUAL PERCEPTION AND VISUAL MOTOR SKULS AT FOUR YEARS OF AGE OF NEUROLOGIALLY NORMAL, EXTREMELY LOW BIRTH WEXGET

CHIL,DREN WKH NEONATAL PERIVENTRICULAR BRAIN INJURY

Suzanne Jeanne Breton

A thesis submitted ui confodty with the requirements for the degree of Master of Arts

Department of Human Development and Applied Psychology Ontario Institute for Studies in Edncation of the

University of Toronto

O Copyright by Suzanne Jeanne Breton 1998

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VISUAL PERCEPTION AND VISUAL MOTOR SKILLS AT FOUR YEARS OF

AGE OF NEUROLOGICALLY NORMAL, EXTREMELY LOW

Department of Human Development and Appiied Psychology University of Toronto, Convocation 1998

Degree of Master of Arts Suzanne Breton

ABSTRACT

The study examines the effects of perïventricular brain insult on a group of

extrernely low birthweight (ELBW) infants at four years corrected age on measures of

visual perception, memory, motor planning and visual spatial manipulation. The

performance of 60 ELBW children, divided into three groups with varying degrees of

periventricular brah insult, is compared to a group of 22 ELBW children without brain

insult. The groups are comparable in ternis of gestational age, birthweight, days

ventilated, bronchopulmonary dysplagia, and size for gestational age. Visual motor

integration was unùnpaired in al1 children assessed regardtess of brain insult status.

Increasing frequency of deficits in the interpretation of visual spatial information and

motor planning are associated with penventncdar damage. This reaches statistical

significance when the most severely affected children with periventncular leukomalacia

or periventricular echoes are compared to the no insult preterm group. There is also a

trend for difficulties on tasks involving visuai perceptuai information and m a o r i to be

associated with increasing severity of brain insult but, the differences are not statistically

significant.

1 wish to thank the many people who contnauted to the development and completion of this thesis. First of all I would like to thank my supervisor Dr. Tom Humphries who provideci invaluable input and feedback and and patiently guided me through the process. 1 would also like to thank Dr. C. Mussellmann for her insight and constructive critisism.

My colleegues deserve my gratitude for their patience and resilience in assisting me h u g h this process and 1 am appreciative of the support of the Department of Rehabilitation Services at HSC, without which 1 may never have finished. Thank you to Marg Schmidt for asseskg most of the chi1dren and taking the tirne to organize and record everythug for me.

Thank you most of al1 to the children and their families for allowing us to share in their growth and development and to leam b r n them.

TABLE OF CONTENTS

LITEUTUIRE R E W W 2.1 Birthweight 2.2 Brain h u i t

2.2 1 Head UItrasound Scanning of Lesions 2.22 Intravenûicular Hemomhage 2.23 Penventricuiar Leukorndacia 2 -24 Periventricular Echodensities

2.3 Bronchopulmonary Dy splagia 2.4 htrauteriae Growth Retardation 2.5 Socioeconomic Status 2.6 Methodological Issues 2.7 Corrected and Unwnected Ages 2.8 Cognitive Outcomes at School Age 2.9 Summary 2.10 Sîatement of Hypotheses

METHOD 3.1 Participants 3.2 Outcome Measures 3.3 Risk Factors

3.3 1 Medical Statu 3.32 Brain Insult Status

3.4 Procedure

DATA ANALYSIS

RESULTS 4.1 Cornparison of Groups on Medical Status Variables 40 4.2 Comprison of Performance Outcomes Among Brain Insult

Groups and the Group with No Brain Insult 43 4.2 1 Cornparisons of MAP Percentiles and VMI Standard Scores 43 4.22 Conprison of Groups on the MAP Risk Categones 48

4.3 Cornparisons of the Groups with DifEerenL Severity of Brain Insult on the MAP Indices Percentiles and the VMI Standard Scores 50

4.4 Cornparison of the Groups with Différent Severity of Brain lasult on the MAP Risk Categories 51

DISCUSSION 53

LIMITATIONS OF STUDY CONCLUSIONS

GLOSSARY

REFERENCE LIST

LIST OF TABLES

Table 1 Means, Standard Deviations and Tests of Signincance for thz Continuous Medical Risk Variables 41

Table 2 Frequency Co-, Percentages and Tests of Significance for the Discrete Medical Risk Variables 42

Table 3 Means and Standard Deviations of Percentiles for the Miller Assessrnent for Preschoolers (MN) Indices and of Standard Scores for the Beery Test of Visual Motor Integration (VMI) for the Four Brain Insult Groups 44

Table 4 Percentages of Miller Assesment for Preschoolers (MAP) Index Scores for Risk Categories Among Brain Insuit Groups 45

LIST OF FIGURES

Figure 1 Frequency Distribution of MAP Nonverbal Index Risk Category Scores for Brain Insuit Groups

Figure 2 Frequency Distribution of MAP Complex Tasks Index Risk Category Scores for Brain Insuit Groups

vii

Chapter 1

As improvements in medical technology and knowledge continue to in~rease the

survivai rates of extremely low birthweight kfànts, the long-tam outcome of these

children is of increasing interest. The pretexm infant is at risk for a number of

complications in the nwnatal period such as retinopathy of prernaturity, intraventncular

hemorrhage, periventricular leukomaiacia, bronchopuimonary dysplagia, necrotizing

enterocolitis, sepsis and hypoxemia The factors associated with major sensory and

neurological deficits are now well recognized but the variables associated with more

subtle difficulties are less easily ppinpointed. New technology allows health professionals

and researchers to visuaiîze the damage to the infant's developing brain through the use of

mobile maniai u1tmsou.d Maging. Reliable imaging techniques now pennit

investigators to examine the correlation between clinically unobservable variables and

more clinically obvious phenornena and long term outcome measures in this population.

Studies done in the past decade have atternpted to document the more subtle deficits in

children who suMve infancy without major sequelae. Their findings suggest that

neurologically normal exbremely Low birthweight infants are at nsk for a variety of

sensory-motor, perceptual, 1-g and academic problems in early and late childhood.

The challenge continues to be to identify which risk factors present the greatest likelihood

of ongoing developmental problems. This study proposes to examine the effets of

neonatal risk fxtors, and especially periventricular brain damage, on the sensory-motor

and visual-motor fiuictioning of extremely low birthweight children at preschool age.

Identifuing children who are havixlg difnculty will as& in the provision of appropriate

intemention and paIiaps alert practiticners to those children who are at risk for school

related problems.

This is a ~tmspective study for which data was collected between the years of

1 989 and 1 996. In this study four groups of preterm children with varying degrees of

hemodage or hypoxic brain i . t are compared on three measures of visual perceptual

and visual motor functioning, to determine if damage to the periventricular area of the

brain produces subtle deficits in chiidren who are ottierwise felt to be normal.

Chapter 2

LITERATURE REVIEW

Many of the medical nsk factors associateci with prematurity and poor outcome

have been studied extensively in the literature and the sequelae following certain injuries

or conditions is well documented. The Iiterature examining the long-terni outcome of

children who are not sipnincantly darnaged is less conclusive. Many of these studies

have looked at preterm infants as a homogeneous p u p based on birthweight or

gestational age at birth and explored their fhctioning at school age. Few, however, have

narrowed the criteria to examine the effects of specific risk factors on the bctioning of

"nomal" preterm children at older ages. In this study the effect of early hemorrhage to

the area of the brain surrouc:~g t e ventricles (small chambers in the centre of the brain

where cerebrospinai fluid is produced) is examined in pretenn cbildren who have reached

four years of age.

Many preterm infmts, as high as 50%, experience bleedhg in the area

surromding the ventricles. This area is especially vulnerable because it is undergoing

rapid growth and development at the t h e that these infants are bom. Bleeding into or

near the ventricles occurs in different degrees. Bleeding can be confineci to a smali area

in the lining of the ventricle (subependymal hemorrhage or grade 1 bleed). If this

hemorrhage ruptures and blood enters the ventricles it is called a grade II bleed. A grade

ID b led occm when the ventricles are so full of blood that they expand and push out

against the brain tissue. A grade IV bled occurs when blood h m the dilited ventricles

entes the brain tissue itseif Preterm infants are &O at risk for sustainllig damage in the

same area of the brain as a result of cell deaîh h m lack of blood supply. This is known

as periventricular (amund the ventricles) leukomalacia Some preterm infants, however,

do not experience any bleeding or ceil death.

This study will focus on the effects of these brain insults on long-term outcome in

children who do not have obvious disabilities, the supposition being that these injuries

produce changes in the developing brain thaî impact on bctioning later on.

The literature on the more cornmon risk factors associated with less than optimal

outcome of children born prematurely wiii be reviewed with a focus on neonatal brain

insult. The major methodological issues will be addressed and the studies of preschool

and school age outcomes will be examined. To facilitate the understanding of this review

the reader is refmed to a glossary of medical terms on page.

2.1 Birthweight

As medical technology improves, more very low birthweight (c1500g) and

extrernely low birthweight (4000g) infants are suMving to school age and their

outcomes are being examined. Accordhg to a study published in 1993 by Wojtulewicz,

Alam, Brasher, Whyte, Long, Newman, and Perlman, the survival rate in a cohort of

infants bom weighing C15ûûg between 1980 and 1987 was 76 percent. Survival of

infants weighing G 5 0 g increased h m 32 percent in the period between 1980-1983 to 54

percent in the period h m 1983-1987.

The morbidity rates of premature infants has been found to be relatively consistent with

approximately 10-20 percent of infants bom weighing 4500g being diagnosed with a

neurological or sensory handicap before 2 years of age (Grogaard, Lindstrom, Parker,

Culley, and Stahlman, 1990; Wojtulewicz et al., 1993). The numbers of extremely low

birthweight (ELBW) Xmts surviving without major sensory, neurological or intellectual

deficits has increased significantly over the p s t decade (Hack, Taylor, Klein, Eiben,

Schatschneider, and Md-Minich, 1994; Wotjdewicz et al., 1993). Recent snidies

examining the school age outcornes of prctam children indicaie that even when more

severe neurological damage is not present, they are at higher risk for more subtle

neurological insults that may give nse to alterations in behavioral development, motor,

sensory and cognitive fhctioning as well as academic performance (Hack, Breslau,

Aram, Weissman, Klein, and Borawski-Clark, 1992; Klein, Hack, and Breslau, 1989;

Ross, Lipper, and Auld, 1991; Saigal, Szatmari, Rosenbaum, Campbell, and King, 1991).

Neurologically intact very Iow birthweight children are reported to fiuiction more

poorly in al1 areas of gros and fine motor performance with extremely low birthweight

children perfonning more poorly than their heavier pretenn peers. Saigal et al. (1 99 1 )

fond that very low birthweight children scored significantly lower on gross and fine

motor assessments than fûiltenn controls, although their mean performance scores were

still within the borderline normal range. However, she reports that 28 percent of the

"normal" (Le. without nemlogical handicaps) extremely low birthweight children scored

in the abnormal range. Crowe, Deitz, Bennett, and Tekolste (1988) found that the overall

gross and fuie motor development of very low birthweight children was intact, but that

their g ros motor performance scores were shifted in the below-average direction. This

stcdy also reported that the cohort of children born weighing 4000g scored significsllltly

lower than îhe group weighing between 1001 - 1500g at birth. Hack et al., (1 992) fomd

significant dekits in fine motor ability at 8 years in very low birthweight children and

Klein et al., (1 989) report signincant differences in fine motor function of very low

birthweight children at 9 years compared to their fixilterm peers. In the 1994 study by

Hack et al., infants bom weighing a 5 0 g performed sipnificantly poorer on ali gross and

fine motor tasks than theV very low birthweight or 111temi p e a s at 7 years. Roussounis,

Hubley, and Dear (1992) fond that very low birthweight children presenting with motor

coordination diffidties but no overt neurological deficit performed particularly poorly

on arithmetic and visuo-spatial tasks.

Numemus studies have found that birthweight is correlated with outcome. The

percentages of children having sipaincant impairment appears to be relatively constant

though a greater number of infants are s d v i n g at lower birthweights and gestational

ages. A greater nimiber of infants a; 2 therefore SUtViving without major neurological

impairment, although there is evidence that they experience subtle deficits.

2.2 Brain Insult

Very low bîrthweight infants are at risk for a number of medical complications

including bronchopulmonary dysplagia, intraventricdar h e m o h g e (IVH), post

hemomhagic hydrocephalus and periventricdar leukornalacia (PVL). Of these,

intraventricular hemorrhage, hydrocephalus and periventricular leukomalacia occur in the

developing brain of the neouate and can cause direct damage to the brain tissue of the

infant. The incidence of intraventricuiar hemorrhage in very Iow bllthweight infants is

thought to be as high as 50 percent and the more immature the infant the greater the risk

of hemorrhage (Levene, 1987). Periventricular leukomalacia has been found to occur in

2-15 percent of very low birthweight infants. The types of overt neurological sequelae

that can occur following such damage is well documented in the Literature; cerebral palsy,

blindness, and mental retardation (Leomd, Clyman, Piecuch, Juster, Ballard and Behle,

1989; Papile, Munsick-Bruno and Schaefa, 1983; van de Bor, Ens-Dokkum, Schreuder,

Veen, Brand and Verloove-Vanhorick, 1993; Vohr, Garcia-Coll, Flanagan and Oh, 1992;

Weisglas-Kuperus, B e , Fetter and S m , 1992; and Williamson, Desmond, Wilson,

Muxphy, Rozelle and Garcia-Rats, 1983).

2.21 Head Ultrasound Scanning of Lesions

Cranial ultrasound scamhg is effective in identification of intraventricular

hemorrhage. The dense echoes on ultrasound correlate with the presence of blood in the

germinal matrix andor lateral ventricuiar system. Papile (1978) desebed a cliissification

system by grades based on the presence and amount of blood in the germinal matrit or

subependymal area and lateral ventricles:

Grade 1 - bleeding is restricted to the subependymai a r a

Grade II - subependymal hemorrhage (SEH) with ruphire of blood into the

ventricles.

Grade III - SEH with blood in the ventricles and ventricula. dilatation.

GradeN - IVH with blwd in the adjacent brain parenchyrna.

Volpe (1995) describes a simila- classification with the exception of Grade IV

intraventricular hemorrhage. He describes periventricular hemorrhagic infarction

complicating major intravenîricular hemorrhage as a m g echogenic Lesion, usudly

unilateral and located on the side of the largest amount of germinal maizïx or

intraventricular b l o d As stated earlier he believes that the mechanism for this lesion is

ischemic necrosis of the white matter as opposed to an extension of the bled into the

periventricular pmchyma

Serial ultrasound scans of premature infants have provided valuable infornation

regarding the time of onset of hemorriiage. Approximately 50% of intraventricular

hemorrhages occur on the first postnatal &y, another 25% on the second &y and an

additional 15% on the third &y (Levene, 1987; Papile ET al., 1978). Therefore screening

done on the fourth postnatal &y would detect approrcimaîely 90% of all hemorrhages

(Papile et al., 1978; Volpe, 1995). Progression of the lesions occurs in about 20 to 40%

of infants, with maximal extent of the lesion attained u d l y within 3 to 5 days of the

initial diagnosis (Volpe, 1995). Periventricular leukomalacia c m often be visualized by

cranial ultrasonography as echolucent cysts (indicative of tissue dissolution) d e r

approximately 1-3 weeks (Volpe, 1995; Perlman et al., 1996) and most cystic lesions are

identifieci by 1 month postnatal age (Calvert, Hoskinç, Fong, and Forsyth, 1986; Perlman

et al., 1996). %or to that, the acute lesions appear in coronal projections as bilaterai

"flare" echodensities adjacent to the extemal angles of the laterd ventricles. On

parasagittal projections the echodensities may be diffusely distributed in the

periventricuiar white mattei or Iocalized to the sites of predilection for penvenhicular

leukomaiacia It is common for the cysts to disappear after 1 to 3 months leaving

enlarged ventricles (indicative of white matter atrophy). Srnail focal areas of necrosis

however are often not detected consistently by ultrsisound. In addition, echodensities,

particularly in the posterior parietal and pareitooccipital regions are very common in the

brain of premature infants with no apparent neuropathological correlate (Volpe, 1995).

What distinguishes these transient echodensities h m periventricular leukomalacia is

their evolution to cysts or to ventncular dilaiaiion. The evolution of cranial ultrasound

imaging and its routine use in ahost ail neonaîal intensive care uni& in developed

countnes has allowed researchers to accmtely document the types and fiquency of

brain lesions in the preterm population.

2.22 Intraventricdar Hemodage

Intraventricular or periventricular hemorrhage begins as a hernonhagic lesion in

the germinal ma& of the developing brain of the praemi infant. The hemorrhage can

be isolated or it can rupture through the ependyrnal lining into the veniricular system

(Levene, 1987). The gexminal matrix is a richly vascular structure that is most

pronounced in the fetus of six to eight xonths' gestation vapile, Bumstein, Bumstein,

and Koffler, 1978). The germinal matrix is the site of glial cell formation and is supporteci

by a hgile matrix of capillaries with thin immature walls. The capillary bed of the

genninal matrix receives a disproportionate amount of the total cerebral blood volume

reaching the brain because of the high metabolic demand of the cells involved in division.

During the perinatal period autoregulation of cerebral blood flow can be unstable,

especially in sick preterm infants, thus hypertensive events can cause rupture of the

capillary bed. Stable preterm infants are more likeiy to have intact cerebrovascular

autoregulation and are less at risk for developing intraventricular hemorrhages.

Fluctuating cerebral blood flow velocity has also been implicated in the occurrence of

intraventricdar hemorrhage (Papile et al., 1978). The mechanics of ventilation of

preterm infants has been found to be primady responsible for fluctuations in cerebrai

blood flow, but hypercarbia, hypovolemia, and patent ductus arteriosus may also correlate

with the occurrence of fluctuations in cerebral blood fiow velocity (Volpe, 1995). In the

mature nmnate a g h l barrier has developed between the ependyma and the germinal

ma& preventing hemorrhages h m bleeding into the lateral ventricles. The matrix

progressively decreases in size to nearly complete involution by appruximately 36 weeks.

Volpe (1 995) describes the possible neuropathological consequences of intraventricular

hanorrhage as germinal matrix destruction, periventricuiar hemorrhagic infiidon and

posthemorrhagic hydmcephalus.

k e lesions might disnipt processes essential to normal brain organization and

might also interfere with myelination and brain growth. White matter necrosis may lead

to diminished total brain white matter (Whiîaker, Feldman, Rossem, Schonfeld, Pinto-

Martin, Torre, Blumenthal, and Paneth, 1996). Papile et al. (1978) observed that 83% of

the infants diagnosed with grades 1 and II intraventricular hemodage, without

ventricular dilatation in the neonatal period, present with some degree of cortical atrophy

seen as prominence of the interhemispheric fissure when scanned at 6 months of age.

The third possible consequence of intraventricular hemorrhage is pos themo~g ic

ventricular dilatation or hydrocephdus. The likelihood of and the rapidiw of evolution of

hydrocephalus after intraventricular hemorrhage is related directly to the quantity of

intraventricular blood (Volpe, 1995). Ventricular dilatation may begin essentially with

the hemorrhage, especially with marked intraventricular hernonhage. More ofien,

dennite ventricdar dilatation and its progression begin within 1 to 3 weeks of the

hemorrhage. In pranature infants there is often significant ventricular dilatation and

increased intracmial pressure prior to the development of rapid head growth. The

cerebral white matter is encroached upon tikely because l e s force is required to cornpress

this immature white matter than to ovemorne the restrictions of the dura and skull (Volpe,

1995). Ventrîcular dilatation in experimentd and human hydmcephaius leads to axonai

stretching and disnrption foilowed by axonal loss and gliosis (Volpe, 1995). These and

other effccts could reflect, in part, disturbance to ascending and descending axons in

cerebral white matter with secondary effects on organizational development of the

cerebral cortex.

In a study nported by Palmer, Dubowitz, Levene, and Dubodz (1982), infants

with intraventricular hemorrhage and ventncular dilatation had a significantly greater

incidence of major handicap at one year as compared to infants with intraventricular

hemorrhage and no dilatation. The infants with ventncuiar dilatation also perfonned

more poorly on clinical assessments of fine motor, gross motor and verbal or social

development than the infants with intraventricuiar hemorrhage and no dilatation and

infants without intraventricuiar hemorrhage.

Few studies have been published examining the effect of intraventricuiar

hernorrtiage and periventncular brain injury on school age outcornes of neurologicafly

normal veiy low birthweight or extmnely low birthweight infants. Vohr, Garcia-Co11

and Oh, (1989) assessed children's abilities on visual perceptual and visual motor tasks at

2 years of age and compared the groups according to severity of intraventricular

hemorrhage. They found that the children with severe intraventricular hemorrhage (grade

III and IV) had more deficits in visual-percephial and visual-rnotor coordination. These

children were re-assesseci at 5 years of age. When the scores of the children with

abnormal or more severe neurologicai findings were omitted, the rcsults demonstratecl

that ail the very low birthweight infmts assessed, irrespective of intraventricdar

hemorrhage status had evidence of subtie gros motor difnculties. The total motor

coordination score was also more abnormal for all of the premature infant groups.

Leonard et al., (1990) compared a group of 5 6 year old children with grades 1

and II Uitraventricular hemoxrbge to a group of children with grades III and IV

intraventricular hemonhge and found that the rates of cognitive deficits increased with

increasing grades of intraventricular hemorrhage. Unfortunately, included in the grade III

and IV intraventricdar hemorrhage group are a number of children (21%) with central

nervous system abnormalities while the children with grade I and II intraventricular

hernotrhage were dl neurologically intact. Roth, Baudin, McCormick, Edwards,

Townsend, Stewart, and Reynolds (1993) found that infants with either normal head

ultrasounds or uncomplicated pe;:ventikular hernodge had sllnilar outcornes when

assessed at 8 years of age. A mal1 proportion of these children was reported as having

major impairments affecting their functional ability. A substantial proportion

(approximately 22%), however, had minor impairments, including abnormal neummotor

signs, and cognitive deficits.

Whitaker et al. (1 996) found a relationship between head ultra-sound status and

vimal-motor integration and visual perceptual skills of very low birthweight children

assessed at six years of age. Children without sevme neurological damage and with

parenchymal lesions or ventricular enlargement performed significantly below children

with isolated germinal matrix hemorihage.

The literature appears to indicate that the presence of intraventrïcular hemorrhage

is related to poor developmental outcornes and that the magnitude of the disability may

be related to the severity of the intraventricula. hemorrhage. However, the literature

examines mostly the correlation between the presence of ïntraventricular hemorrhage and

the presence of significant neurological and sensory abnomalities. The association

between intraventricular hemorrfiage and more subtle dilEculties has not yet beai fdiy

invesbgated, though initial findings appear to indicate increasing difficulties in a variety

of areas with iacreasing severity of injury.

2-23 Periventricular Leukomalacia

Periventricular leukomalacia is an ischemic event characterized by necrosis of the

brain tissue due to lack of blood supply. Periventricular leukomalacia develops in areas of

the brain that represent arterial border zones or end zones (Volpe, 1995). These arterial

border and end zones are essentially "watershed areas" and are therefore more susceptible

to a fdl in perfusion pressure and cerebral blood 80w. Systemic hypotension can occur

postnataily in pmnature infants secondary to events such as perinatal asphyxia,

pulmonary disease, sepsis, patent ductus artenosus (PDA) and apneic spells (Papile et al.,

1978; Periman, Risser, and Broyles; 1996, Volpe, 1995).

The predilection for pexiventricular leukomalacia in less mature infants may relate

in part to the development of both the penetmting cerebral and the periventricdar

vasculatures, periventncuiar leukomalacia generally occurs in the regions between the

vascula. territories of the anterior, middle and posterior cerebral artenes. hadequate

pemision through the deep medullary arteries of the immature brain can cause ischemic

infarction in these border wnes. With focal periventricular lesion, small cavities develop

which can be visitaIized readily by cranid uitrasound. Subsaquently, m y e h l o s and

ventricular dilation are the chronic sequelae. An important sequela of periventricular

leukomalacia is the destruction of the subplate zone. The subplate neurons are considered

to play a critical role in cerebral organization. These cells receive inputs ascending nom

the thdamus and distant cortical sites and extend collaterals to the cerebral cortex. The

subplate nemm provide a site for synaptic contact for axons ascending h m the

thalamus and other cortical sites. These are termeci "waiting" cortical afferents because

their targets in the cortical plate have not yet &ved or dinerentiated. Subplate nemm

are also thought to guide ascending axons to their targets in the cortical plate. If the

subplate newons are eliminated, cortical Serents rnay fail to move into their appropriate

sites in the cortex. A M e r fimction of the subplate neurons is involvernent in cerebral

cortical organization. The subplate layer reaches a peak between 22 and 34 weeks

gestation which corresponds with the times of occurrence of intraventricular hemorrhage

and periventricular leukomalacia If these insults disnpt the subplate neurons this could

interfere with the development of crucial neuronal connections and projection systems

and perhaps impact on cortical organization and fùture cortical hctioning (Volpe,

t 995).

Bozynski, Nelson, Matalon, Genaze, Rosati-Skertich, Naughton, and Meier

(1 985) examinai the effects of periventricular leukomalacia in a group of 100 preterm

infants bom weighing less than 1200g. Ail of the infants who presented with cavitary

periventricular leukomalacia developed cerebral palsy by 24 months of age.

Fazzi, Orcesi, Caf'fî, Ometto, Rondini, Telesca, and L a d (1994) reported that

approximately 65% of infants identifiai as having srnaIl(< 5mm). focai periventricular

cysts in the neonatal period were found to have minor neurological or cognitive deficits at

5-7 years of age. Importantly, they note that a numba of these children who were

assessed as being neurologicaUy normal at 2 years of age were re-classified as having

minor neurological deficits at 5-7 ycars. The mental development of these children was

essentidy nomial though they tend to present with a higher verbal compared to lower

performance and motor scores. They suggest that these hdings may indicate slight

damage of neuromotor pathways. Children with s m d anteriorly located cysts were

fond to have an even better prognosis, presenting with only minor visual disorders or a

nomal outcome at 5-7 years.

The relationship between bilateral cystic or cavitary periventricular leukomalacia

and adverse outcome is well documented in the literature. The effects of mild

periventricular leukomalacia on le ng-tezn neurodevelopmental fiinctioning are less well

defineci but the literature seems to suggest that these children are at risk for developing

subtle deficits at school age.

2-24 Periventricular Echodensities

Controversy stili exists in the literature regarding the significance of

periventricular echodensities without cyst formation (Perlrnan et al., 1996).

Perlma. et al. (1 996) and Volpe (1 995) report that periventricular achoes most likely

reflect the presence of what was previously referred to as a grade IV intraventricular

hemorrhage with the echoes representing the damage to the surroundhg tissue fkom the

bleed.

Bennett, Silver, Lemg, and Mack (1990) graded echodensities on cranid

ultrasound on a s a l e of O to 3, with O indicating no echodensities, 1 and 2 indicating

increasing degrees of observed echodensities without cysts and 3 representing cystic

formation. They found no sipnincant relationship between non-cystic echodensities and

poor developmental scores or overall neurodevelopmental outcome at 18 months of age.

Fazzi, et al. (1994) reported that, of the children they assessed with periventricular echoes

without cystic evolution, 50% developed cerebral palsy and the remainder had either

minor visuai or cognitive deficits or were considered nomal at 2 years and remained in

the same categones at 5-7 years.

Levene, Dowling, Graham, Fogelman, Galton, and Philips (1992) studied the

motor fiuiction of a group of very low birthweight children with non-cavitating

'periventricular echodensities' or 'periventricular flarest at 5 years o f age. A prolonged

flare was defined as "an appearance of relative increased echodensity in the

periventricular region seen in both coronal and parasagittal views, and persisting for at

lest 2 weeks and not undergohg cystic degenemtion". They found a statistically

significant decrease in manual dexterity in the group of children with intraventricular

hemorrhage and prolonged flare as compared to the group with normal head ultrasounds.

When compared to children with intraventricular hemorrhage and no parenchymai

involvement alone or prolonged periventricular flare alone, the différence was not

significant. As well they noted that relatively minor ultrasound appearances such as

prolonged flare and grades 1 and II intraventricuiar hemorrhage are associated with mild

motor impairment but that this has a small main effect compared with low birth weighî.

The impact of periventricular echoes or fiares found on head ultrasound on

function at preschool and school age is even less well recordeci in the literature than the

effects of d l pexiventricular cysts. It does appear, howwer, that these in suit^^ though

not generally resulting in significant motor or cognitive impairment, may affect

performance in more subtle ways. Differences in grading of lesions and terxninology

make this issue more difncult to interpret.

23 Bronchopulmonary Dysplagia

Bronchopulmonary dysplagia (BPD) is a c h n i c respiratory disease that primarily

affects premature newbom infants. It is considered an iatrogenic disease caused by

oxygen toxicity and barotrauma resulting fiom pressure ventilation (Meremtein, and

Gardner, 1989). For the diagnosis of bronchopuimonary dysplagia the following criteria

generally need to be MIIed: 1) primary lmg disease requiring positive pressure

ventilation within the first three days of life; 2) continued respiratory insufficiency

because of pulmonary pathology requiring supplementary oxygen past 30 days of life to

maintain a Pa02 over 50 mm Hg; and 3) radiographie changes progressing to a pattern of

altemahg areas of focal emphysema and atelectasis, persisting for at least 30 days

(Markestad and Fitzhardinge, 198 1).

Impaireci growth and development have been reported as common sequelae in this

group of infants, but long term follow up is rare. Robertson, Etches, Goldson, and Kyle

(1991) followed a cohort of preterm infants with and without bronchopuimonary

dysplagia Their results showed that the children with bronchopulmonary dysplagia did

not differ significantly on measures of neurodevelopmental or psychoeducational

performance from their matched preterm p e m at 8 years of age. Markestad and

Fitzhardinge (1 98 1) reporteci appropriate developmental bctioning in 75 percent of their

20 survivors of BPD at 18 mon& of age and suggested that outcome seerned more

relateci to perinatal and neonatal events tha. to the presence of chronic lung disease. The

children with Bayiey scores of l e s than 85 had statistically significant longer initial

hospitalizations than the other chilciren in the sample. Sauve and Singhal(1985) report

that the long terni neurodevelopmmtal outcome of infants with bronchopulmonary

dysplagia did not diffa significantly b m that of matched controls, though it is unclear at

what age the children were assessed and whether the bronchopulmonary dysplagia and

control infants were assessed at the same ages. Improvement or lack of improvement in

outcome over t h e could confound these results if the cohorts were assessed at diserent

ages. t

Leonard et al., (1 989) found that, in children with bronchopulmonary dysplagia

but no intraventricular hemomhage, the need for supplemental oxygen by itself had little

relation to school age neurologic and cognitive performance. None of the children

studied had neurologic abnormalities and only 7% had cognitive deficits. Meisels,

Plunkett, Roloff, Pasick, and Stiefel(1985) dispute these conclusions. They compared a

cohort of premature infants with respiratory distress syndrome to a cohort with

bronchopuImonary dysplagia Both groups were f k e of CNS, newomuscular or sensory

disorders, hydrocephalus, inîraventncular hemorrhage more than grade II, retinopathy of

prematmity, congenital malformations, metabolic disorders, severe hyperbihbinemia,

or intrauterhe growth retardation. No significant medical or neurological difference was

found between the respiratory distress syndrome and bronchopulmonary dysplagia p u p s

in the second year of life. However the developmental outcornes of the infants with

bronchopulmonary dysplagia were significantly Iess optimal that those of the infants with

respiratory distress syndrome. The children with bronchopulmonary dysplagia performed

in the low-average range of ability on tests of mentai, psychomotor, sensorimotor and

language development Among the infants with bronchopulmonary dysplagia, 35%

displayed a delay of more than 1 SD on the mental development Index (MDI) and 47%

were below 1 SD on the psychomotor development index (PDI), of the Bayley scales of

infant development (Bayley, 1969), compared to 5% and 10% respectively for the

children with respiratory distress syndrome.

Landry, Fletcher, and Denson, (1993) found that children with bronchopulmonary

dysplagia were functioning in the low average range of motor development at 3 years and

significantly below the low birth weight children with respiratory distress syndrome with

or without intravenûicular hemorrhage. The children with respiratory distress syndrome

and Grade N intraventricular hemorrhage were also functioning signi ficantly below the

respiratory distress syndrome - htraventricular hemorrhage groups but not in relation to

the bronchopulmonary dysplagia group. However, Landry et al., (1 993) include

children with grades III and IV intraventricular hemorrhage in their bronchopuhonary

dysplagia group making it impossible to separate out the independent effects of

bronchopulmonary dysplagia on developmental outcorne. Bozynski, Nelson, Matalon,

ODonnell, Naughton, Vasan, Meier, and Ploughman (1986) assessed the impact of

prolonged mechanical ventilation and intracranial hemorrhage on developmental

progression in a cohort of very low birthweight children. Mechanical ventilation was the

best predictor of performance on the Bayley MD1 and PD1 at 8, 12 and 18 months of age.

The children who experienced prolonged mechanical ventilation had a higher incidence

of cognitive and motor delay as compared with those who did not receive it.

Thus Bronchopulmonary dysplagia has consistently been found to negatively

affect the early growth and development of preterm infants but the impact of this

condition on long temi development is l a s ciear. Childten with Bronchopulmonary

dysplagia do not, as a group, appear to present with severe motor or cognitive

impairments at school age but whether they present with more subtle difnculties has not

been well investigated

2.4 Intrauterine Growth Retardation

Children are considered small for gestational age (SGA) when their birthweight is

two standard deviations less than the mean for gestational age. Sung, Vohr, and Oh

(1 993) compared the neurodevelopmental outcomes of very low birth weight infants with

inmuterine growth retardation to control subjects matched by birth weight and

gestational age. The developmental outcomes at 1,2 and 3 years of the SGA infants were

significantly lower than those of appropriate for gestational age (AGA) infants, matched

by gestational age status, but comparable to AGA infants matched by birth weight status.

Therefore children who were bom SGA but not necessarily preterm, perfoxmed more

poorly than children bom p r e t m but of appropriate birth weight for the* gestational age.

Seigel(1982) found thaî very low birthweight children in general were delayed in the

areas of perceptual abilities, memory and motor skills in cornparison to fullterm children

at 5 years of age. There were no signïficant differences between the appropnate for

gestational age and the small for gestational age preterm groups. Srneder, Faxelius,

Bremme, and Lagerstrom (1 992) report that, in their cohort of very low birthweight,

small for gestational age children, none presented with overt neurological abnormality,

but more than 50% of these children had mild deficits in motor and cognitive bcbon,

most typically in coordination and proprioceptive tasks and strategy formation, spatial

ability and non-verbal problem solving. They did not, however, compare this group to a

cohort of very low birthweight infmts that were appropriate for gestational age to

examine the effects of being small for gestational age versus the effects of low birth

weight. The cohort of smali for gestational age very low birthweight children studied by

Vohr et al. (1 989) was cornpared to a cohort of appropnate for gestational age very low

birthweight childrcn at 3 years; no statistically significant differences were noted between

the groups in ternis of major neurological outcorne. Assessments to determine the

presence of more subtle motor deficits ware no? done in this study.

Conclusions regarding the neurodevelopmental outcornes of children bom small

for their gestational age have not yet been established. It appears that these children are

not at high risk for developing major neurological problems as a resuit of being bom

small for their gestational age but they may be at risk for experiencing more subtle

difficulties at school age.

2.5 Socioeconomic Status

Socioenvironmental disadvantage has been found to have an adverse effect on

intelligence as rneasured by standardized IQ tests (Hack et al., 1992; Ross et al., 199 1 ;

Saigal et ai., 199 1 ; Whitaker et al., 1996). Controversy remains as to whether

socioeconomic façton are more important than birthweight in predicting developmental

and intellectual outcomes of premature infants (Hack et al., 1992; Hunt, Cooper, and

Tooley, 1988; Resnick Roth, Ariet, Carter, Emerson, Hendnckson, Packer, Larsen,

Wolkuigy Lucas, Schenck, Feaniside, and Bucciarelli, 1992; Ross et al., 1985). Resnick et

al., (1992) found that race and matemal education were the main predictors at school age,

of mental development and that birthweight had an impact only in infants weighing less

than 100og.

Seigel(1982) developed a risk index based on a variety of reproductive7 perinaîal

and environmental variables in order to predict the developmental outcome of very low

birüiweight infants. She found that the perinataI and reproductive variables were

typically more related to perceptual and motor development and variables such as

matemal education and SES to language development. Overall she concluded that

severity of illness during the perinatal pexiod and infant test scores independent of social

class, were the b a t predictors of outcome at older ages. In his review Scott, (1 987)

reported that associations with low social class were found for mental retardation, global

developmental delays, speech delays, and behavior disorders, but not for motor delays or

cerebral palsy. Vohr et al. (1 992) found that SES contributed signincantly to the

prediction of cognitive status at 5 years of age, but did not have any relationship to

neurologie status or motor fiinction.

In summaryy SES has been found to be correlated with specific developmental

outcomes, but is less Likely to correlate with perceptual and motor abilities of preterm

children at preschool age.

2.6 Methodologid Issues

The literature is ripe with outcome studies of very low birthweight and extremely

low birthweight infants which encompass almost aII aspects of school related

performance such as gros and fine motor problems, visual- motor rIifficulties,

behavioural and attentional problems, laquage deficits, memory pmblans and a c a d d c

difficdties. Aylward and Pfeiffer (1989) and Ornstein, Ohlsson, Edmonds, and AsRalos

(1 99 1) published reviews of a large number of empincal studies fiom the literature of the

past ten years. Nevertheless, conclusions regarding the long terni outcomes of this

population are difficult to make due a number of methodological limitations of the

literature. Many studies used heterogeneous populations, often with inadequate

descriptions of the participants included. The measurement of dernographic factors and

the length of follow up were ofien inadequate to assess more subtle intellectual and

neuropsychologkal outcomes. Considerable variation was found in the type of outcome

measured; investigators have rneasured cognitive, motor, or neurologie fûnction, or a

combination of these, while others have combined scores £kom different areas into a

global measure of outcome. Unifonnity in diagnostic categories is also lacking and

severely handicapped cbildren were often included in the çamples. Correction or non-

correction of age for prematurity was also not unifomily applied, and a number of studies

even failed to report whether scores were analyzed acwrding to corrected or

chronological age.

The lack of uniform methodology and tenninology in the large number of studies

on the pretem population makes hterpretation of the results chdlenging.

2.7 Corrected and Uncomted Ages

Test scores can be interpreted acwrding to the children's uncomcted or corrected

ages at the time of assesment As infants are bom and surviving at increasingly lower

gestational ages, this choice can impact significantly on the results. Landry et al., (1993)

propose that scores corrected for degree of prematurity differentiate transient

developmental effects of prematiirity h m persistent deficits causeci by ceqtral nemous

system damage. As premature infants are now surviving at increasingly lower gestational

ages, cornparison to their chronological peers could disadvantage these children.

Rickards, Kitchen, Doyle, and Keily (1 989) suggest that the reduction in developmental

test scores using the child's uncorrected age increases with increasing prematurîty at al1

ages. The age at which this reduction becornes clinicdly unimportant also increases with

the degree of prematurity. Seigel(1983) feels that the use of correction will reduce or at

times remove the apparent diffaence betweer: preteni and Mt- children but may not

result in the most accurate prediction. Therefore the decision to correct for prernatunty

may be dependent on the question involved.

In summary, the use of corrected or uncomected age scores remains an area of

contention. The age at which correction is thought to become clinically unimportant

increases with increasing prematurity. The use of corrected age is agreed to be more

appropriate when extremely low birthweight p r e t m children are being studied to

determine if they present with deficits in specific areas of functioning that may be due to

central nexvous system damage.

2.8 Cognitive Outcornes at School Age

Seventy-five to eighty percent of very low birthweight children are reported in the

literature as having an IQ within the normal range (%5) (Breslau, Klein, and Men, 1988:

Hack et al., 1992; Klein et al., 1989; Ross et al., 1991; Teplin, Burchal, Johnson-

Martin, Humphry, and Kraybill, 1991). Though extremely low birthweight children as a

group perform in the "nomal" range on tests of cognition they are, according to Saigal et

ai. (1 99 i), significantly disadvantagai compared to matched contmls. The full scale IQ

of extremely low birthweight children studied by Saigal et al. (1% 1) was found to be 13

points lower than the fiilltenn wntrols. Halsey, Collin, and Anderson, (1993) report a

general cognitive index score for extremely low birthweight children 16-1 8 points lower

than children boni weighing 1500-25008 or born fullterm. Abel-Smith and Knight-Jones,

(1 990), state that the mean scores on the McCarthy Scales were significantly lower for

very low birthweight children than for a control group of fulltemi children. Crowe et al.,

(1 988) found the >1000g children achieved a significantly better Wechsler Preschool and

Primary Scale of Intelligence (WPPSI) score than children bom weighing c l 000g.

Kitchen, Rickards, Ford, Doyle, Kelly and Ryan (1989), however, report an irnprovement

in cognitive function of extremely low birthweight children between the ages of 2 and 5

years- At 2 years these children scored significantly lower than a group of heavier

premature infants on the mental development index of the Bayley Infant Devdopment

Scales. Between 2 and 5 years, however, the extremely low birthweight children

improved enough to achieve a mean WPPSI full scale score almost identical to that of the

very low birthweight infants.

Specific cognitive deficits have been identified in very low birthweight and

extremely low birthweight populations. Klein et al., (1989) reported significant

differences between very iow birthweight and fullterm children on cognitive abilities that

are visually mediated, such as spatial relations and visuai matching, and on visual-motor

integration skills. A number of other studies have found deficits in visual perceptual and

visual-rnotor integration abilities of very low birthweight children (Hack et al., 1992;

Hack et al., 1994; Hdsey et al., 1993; Klein, Hack, Gallagher, and Fanan>& 1985; Saigal,

Rosenbaum, Szatmari and Campbell, 1991).

Abel-Smith and Knight-Jones (1990), Hack et al. (1992) and Ross et al. (1 991) aiso found

that very low birth weight children have deficits in expressive and receptive language

abilities and memory. Fnsk and Whyte (1994), however, report that no significant

differences at six years of age were noted on a number of language and memory tasks .

between a full tem wntrol group and a group of very low birthweight children with

nomal intelligence and without periventncular lesionç. Any language and memory

impaiments that were observed were a direct function of the presence and extent of

periventricular damage sustained during the neonatal penod; the children with the more

severe lesions obtained the lowest scores on the language and memory tests.

Despite the fact that intelligence scores and tests of cognitive functioning tend to

be within the nomial range, very low birthweight children are more likely to experience

acaàemic difnculties than their fullterm peers. Klein et al. (1989) report that 40 percent

of very low bvthweight children repeat one grade. Saigal et al. (1991) noted thaf by

grade 3,39 percent of extremely low birthweight children are rated by teachers to be

perfiorming below grade level and the same proportion are receiving specid education

sumort-

Pretenn children, though achieving IQ scores within normal limits, appear to

score more pwrly than their fullterm peers. As well, more specific cognitive and

leamïng difficulties appear to be creating school related problems in the very low

birthweight and extremely low biahweight population.

2.9 Snmmary

The literahire examining the neurodevelopmental outcornes of very low and

extremely low birthweight children appears to indicate that these children are at higher

risk than their fulltemi peers for experiencing problems in a nimiber of anas. A

consistent percentage of these infants develop signincant motoric, cognitive a d o r

sensory deficits before two years of age but the majonty of extremely low birthweight

infants survive without severe impainnent. Howe::q mctoric, cognitive and academic

difficulties have been identified repeatedly in this group even when children with severe

neurological, sensory or intellectual deficits are excluded nom the study populations. A

number of investigators report di fficul ties in visual perceptual and visual-motor

hctioning and these difficuIties appear to be even more evident in children experiencing

increasingly severe neonatal periventricular brain insults such as grade III and N

intraventncuiar hemonhage and periventncular leukomalacia Poorer developmental

outcornes are also associated with Bronchopulmonaty dysplagia and intrauterine growth

retardation making it important to wntrol for these factors in the present study design.

Socioeconomic status is felt to impact more on language mediatecl abilities and not visual

perceptual and motor fiinction and was therefore not taken into account in this study.

More investigation is still needed to determine which of these children are most at nsk.

The objectives of the present study are: 1) to compare the developrnental visual

perceptual and visual rnotor outcomes of extremely low birthweight four year olds who

show increasing sever@ of brain injury to a group of extremely low birthweight children

without hemorrhaging, and 2) to compare the developmental outcomes of the extremely

low birthweight children with varying degrees of brain injury. As severe injury to the

periventricular region of the brain is huwn to cause neurological darnage resulting in

cerebral palsy in a signifiant proportion of extremely Iow birthweight children, and the

long-temi effects of less severe injury are not well known, the effects of these perinatal

and neonatal brain insults on the developmental fùnctioning of cfiildren who do not

develop cerebral palsy, sensory impakments or mental retardation is of interest to

clinicians working with these children and their families. Increased knowledge as to the

outcomes of these preterm children may as& health care providers in identifjmg

children who are at the greatest risk for developing more subtle difficulties in functioning

at preschool and school age, and in programming for these children's needs in the fiiîure.

In the present climate of budgetary restraint, being able to focus long-terni follow up and

screening on those preterm infants at greatest risk will allow us to make educated

decisions as to which children to follow and what types of difficulties they may be at risk

for developing, while allowing the least number of children to fall through the gaps in the

sys tem.

2.10 Statement of Hypotheses

This study will compare specific areas of prwchool performance at four years

corrected age of children bom weighing under lOOOg and who do not have severe

neurological or developmental conditions such as cerebral palsy or mental retardation.

The children are grouped based on their head ultrasound results (indicating the severity of

bleeding) and compared to a gmup of extremely low birthweight children with normal

head ultrasounds (Le. no bleedmg). The four groups are as follows; group A has no

bleeds, group B has mild bleeds (grades IlII intraventricular hemorrhages), group C has

more severe bleeds (grades EUW intraventricular hemorrhages), and group D has damage

refleaing ce11 necrosis @eriventricular leukomdacia~periventricular echoes). The groups

are comparable on other factors that could mount for preschool test clifferences between

thern, including; birthweight, numba of days ventiiated, presence or absence of

bronchopulmonary dysplagia (BPD), and weight for gestational age (AGAISGA).

The hypotheses to be tested are that:

1) Extremely low birthweight children with brain injury will perfomi significantly more

poorly on tests of visual perceptuai, spatial, and visual-motor integrative functioning than

those without brain injury. These skills are chosen as they are reportecl in the literature as

areas of weakness for this population (Hack et al., 1992, Klein et al., 1985 Saigal et ai.,

1991). They are aiso thought to be performance components that impact on the

development and rnastery of many school skills. Occupational therapists assess and

provide recommendations and intewentions to remediate difficdties in these domains.

The author of this thesis has an interest in these domains because she is an occupational

therapist. Specifically, it is hypothesized that children in groups B, C, and D will show

significantly poorer performance than children in group A on tests of visual percephial,

spatial and visual-motor fhctioning. This is hypothesized because the children in group

A do not have bleeds and the other chifdren dl have insults to the brai. in and around the

venûicular system that rnay impact on the development and hture fiinctioning of the

brain, thereby meating subtle denicits in certain areas of performance.

2) The severity of periventncular brain d t will relate negatively to visual perceptual,

spatid and vid-motor abiiities: the greater the insult the poorer the performance.

Among the children with bleeds, it is therefore anticipated th& group D wiil perfonn

more poorly than group C and B, and group C wiii perform worse than group B,

refiecting the negaîive effect of increasing severity of brain insult on hctioning.

Chapter 3

METEOD

3.1 Participants

The cohort in this study is comprised of 82 extremely low birih weight (ELBW)

(Le. less than 1 OOOg), preterm infants attending the integrated nematal folIow-up

program of two hospitals in Toronto, Canada. The children participating in this program

are survivm of one inborn Neonatal Intensive Care Unit (NICU) and one outbom NICU

serving the region of Central East Ontario, including Metropolitan Toronto. These

children, bom between 1989-1993, were selected fiom a larger group of extremeIy Iow

birthweight children because they meet the following criteria: (1) al1 have birthweights

between 501 and 1001g, and range in gestational age from 24 to 33 weeks; (2) none have

abnormalities of the brain other than intraventricular hemorrhage, periventricular

leukornalacia or periventncular echoes; (3) al1 are fk of major sensory (Le. blindness,

d&ess) or motor complications (Le. cerebrai palsy, neuromuscular disorders); (4) none

showed a severe cognitive deficit on a 18-24 month DISC Screen or Bayley assessment;

(5) dl speak and understand English enough to participate in testing procedures. There

are 38 male children and 44 fernale children in the sample. The rnean corrected age of

children at testing was 4.1 years.

3.2 Ontcome Maures

Two measures were used; the Miller Assessrnent for Preschoolers (Miiler, 1988)

and the Beay Test of Visual Motor Integration meery, 1989). The Miller provides an

evaluation of visual perceptual, spatial, and motor planning abilities. The Beery

evaluates visual-motor integration skills.

Two Indices of the Miller were selected which have a minimal motor component,

whereas the Beery requires use of paper and pencil for task completion. These abilities

are noted in the literature as being areas of wealaiess for very low birthweight children as

well as being wrrelated with later academic performance, especially in the earlier grades

(Hack et al., 1994, Halsey et al., 1993, Ross et al., 1991). Data was coliected on gross and

fine motor fünctioning, but was not used in this study due to poor refiability of the

measures utilizd All test scores were Uiterpreted according to the children's correcteci

age.

3 -2 1 Millet Assessrnent of Preschoolers lMAP)

The Miller Assessrnent of Preschoolers (MAP), (Miller, 1988) is a standardized,

n o m referenced screenhg tool that provides an ovenriew of the child's developmental

status. The MAP is designed to identify children who exhibit moderate problems which

may affect one or more areas of development, but who do not have obvious or severe

problems. Deloria (1995) describes the MAP as the 'best available screening test for

identifjrhg preschool children with moderate "preacaderni~'~ problems'. Adequate

validity and reliability were established for the test. It was standardized on a large

random sample (n=10 14) of normal children between 2.9 and 5.8 years which was

stratifiecl for each age and sex.

Content validity studies show that the differemt subtests measure distinct functions

of the child's performance. Test items discriminate significantly at <. 01 level and subtest

indices contribute cqually (r = $47 to .778). Only test items that discriminated mong

the lowest 20% of the nomial sample were retained. Reliabdity was addressed through

inter-rater reliability, test-retest reliability and interna1 reüability of the whole test as well

as standard error of mea~uement. Inter-rater reliability is -98 for the entire test and -99

and -98, respectively, for the Nonverbal Index and the Complex Tasks Index, the two

subtests used in this study. The two subtests used have test-retest reliabilities of .94 and

-91. The intemai reliability, which was only calculateci for the test as a whole, is .79.

The standard error is -05%.

The MAP was designed to precisely identa diffaences among the lowest 25% of

children and has much less precision for the upper 75% (Delona, 1995). The test is

specifically designed to identify children most likely to be at nsk for problems, and

therefore concentrates on pdomance at the lower end of the spectrum. It cannot be used

to identiQ children bctioning at the upper end of the spectrum. The upper ceiling of

many items represents only average performance (Millx, 1948). The scores are recorded

as percentiles and performance is classified as follows: a child fiinctioning at or below the

5th percentile is considered at highest risk for dysfunction, a score between the 6th and

25th percentiles suggests that the child is at milder risk but should be monitored very

carefully, and a child scoring above the 25th percentile is considered to be within normal

limits. Scores cm be obtained on each of the Performance Indices to identify specific

areas of strength and weakness. The percentile scores are not tnie interval scores, they

show each child's position relative to the standardization sample, but not the amount of

difference between scores, Le. performance differences between two percentile scores at

different regions of the scale may not be equivalent. For example, the difference in

performance between 30 and 36 may not be the same as the diffêrence between 90 and

96. Furthmore, because there are more actual scores available at the bottom end of the

scale, the test discriminates better among low scoring children

The MAP scores are recorded in two ways for this study: percentiles as well as the

child's nsk category. The risk category scores reveal more clinically relevant

information regarding the child's hction.

The two indices used for this study are the Nonverbal Index and the Complex

Tasks Index. The Nonverbal Index measures visual memory and visual-spatial

perception in several ways. The children are required to demonsirate ability in object

memory, sequencing, simple puzzles and a figure ground ta&. The object memory task

involves showing the child a number of familia. objects and then covering them while

removing one object. The child is then asked which object has disappeared. The

sequencing task requins the child to place blocks in a box in order nom left to nght. The

puzzles are two or three piece puzzles of a car and a tricycle. In the figure ground task,

the children are asked to h d a number of familiar objects hidden in a picture of a

playground scene.

The Complex Tasks Index consists of items that involve cornbining visual spatial

and motor planning abilities. The tasks include copying two block designs fkom a mode1

and Mitating postures assumed by the examiner. The child is also required to draw a

picture of a person. Moving a small bead fiom one end of a flat maze to the other is the

1st item on this index.

The Nonverbal Index requires minimal motor ability in order to complete the

items whereas the Complex Tasks Index involves more skilled motor functioning and the

integration of motor and other perceptual skills. Therefore children with motor problaw

or CiiffIcuity in integrating various abilities may experience niffIculty on the Complex

Tasks Index, but not on the Nonverbal Index.

3.22 Beenr Develo~mentai Test of Visual Motor Inteption WMI)

The Beery Developmental Test of Visual Motor Integration 0, (Beery, 1 989),

is a developrnental sequence of 24 geometric forms to be copied with paper and pencil.

Children between 4 and 5 years of age are asked to wpy a vertical iine, a horizontal line,

a circle, a cross, a right and left oblique lhe, and a square. The Beery is a nom

referenced, standardized test designed to assess the visual motor and eye hand

coordination skilis of children. The median inter-rater reliability is .93. The average

test-retest reliability is -8 1. The concurrent validity of the Beery has been determined

fiom a few sources; correlation between the VMI and measures of handwriting (.42), and

correlations between the VMI and the Bender Gestalt test (.41 to .82). The VMI

correlates highly (-89) with chronological age.

The test noms were derived nom a nomal sample of children in the United

States and then replicated with a variety of ethnic and cultural groups. The total sample

consisted of 5,824 children between the ages of 2.6 years and 19.0 years. Concurrently,

the Beery is correlateci with academic achievement, especially in the primary grades, and

is thought to measure the key factor for handwriting perfoxmance. Evidence for predictive

validity is mixed, with some investigators bding moderately strong correlations between

performance on this test and later achievement, and others reporting little relationship.

Results are expresseci in terms of standard scores, with a mean of 100 and a standard

deviation of 15, as wel1 as percentiles.

3 3 IRisk Factors

3 -3 1 Medical S tatus

Birthweight was measured in grams. Children were considered SrnaIl for

Gestational Age (SGA) when their birthweight was two standard deviations l a s than the

mean for gestational age based on the Usha-McLean cunres for a Canadian sample

(Usher & Mc- 1969). The presence or absence of Bronchopulmonary Dysplagia

(BPD) was made on the basis of radiographie evidence at the time of discharge h m the

Neonatal Inteasive Care Unit.

The total number of days that the infaats received mechanical ventilation was

counted (# days) and the infants' gestational age was d e t d e d at the time of birth using

the clinicai rnethod descnied by Dubowitz, Dubowitz and Cmldb-g (1970) and recorded

in number of weeks.

3.32 Brain Lnsult Status

The 82 children were classified into one of four groups based on increasing

severity of brain injury. Children with nomal uitnisound findings were assigned to

Group A (n= 22,7 boys, 15 girls). Children with grades 1 or II intraventricular

hemorrhage were assigned to Group B (n= 23, 14 boys, 9 girls). These grades are

grouped together as the hemorrhages are wnfined to the ventricles and are not associated

with dilatation of the ventricles or damage to the brain tissue. Children with grades III or

TV intraventricular hemorrhage were assigned to Group C (n= 19.6 boys, 13 girls). These

hemorrhages are associatcd with expansion of the ventricles leading to compression of

the cerebral tissue or extension of the blood into the smmding tissue (Papile et al.,

1978; Volpe, 1995). Children with periventricula. leukomalacia and those with

periventricular echoes were assigneci to Group D (n= 18, 12 boys, 6 girls). Periventricular

leukomalacia is an ischaemic injury causing tissue necrosis and cavity formation.

Increased echogenicity is thought to represeni early signs of periventricular leukomalacia

Periventricular echoes are thought to reflect damage to the m m d i n g tissue fiom a

Grade IV intravenüicular bleed, either reflecting extension of the bleed, (Perlman, et al.,

1996), or due to ischemic necrosis of the tissue (Volpe, 1995). The lesions are combined

in Group D as actual damage to the cerebral white matter has likely o c c d .

Severity of intraventricuiar hemorrhage was coded accordhg to the classification

system of Papile (Papile et al., 1978): Grade I - hemorrhage restricted to the

subependymal layer, Grade II - hemorrhage without ventncular dilatation; Grade III -

T hemorrhage with ventricu1ar dilatation; and Grade IV - hemorrhage with parenchymd

damage. Penvenû-icular leukomalacia (PVL) was also recorded, as were Perivenûicular

echoes which appeared as prolonged flares not progressing to cysts. Some children have

echoes early on which later disappear. Therefore the echoes had to appear on more than

one ultrasound to be classifieci as penventricular echoes for this study. Generally children

with echoes have at le& one subsequent dtrasound to clariQ this particular issue.

Eariy periventncular leukomalacia is observed on ultrasound as areas of echodensity

&et approximately 1 -3 weeks (Perlman et al., 1 996). Some cystic lesions are not

identified until after one month postnatal age (Calvert et al., 1 986, Perlman et al., 1996).

Therefore some infants who were transfmed or discharged prior to that t h e might have

been incorrectly coded in this study as having only penvenbcular echoes whereas cysts

achially developed later. The most severe ultrasound hding was recorded for each child.

The majority of the infants had an UltraSound within the f h t week of Iife, and a second

completed in the second week or later. Some infants were M e r scanned later, but

others were not since they were transfened to a community hospitd as soon as they were

medically stable. Some secondary insults may therefore have been misseci in these

infants as periventricular Leukomalacia sometimes develops later in the absence of early

periventricular echoes (Papile et al., 1 978).

3.4 Procedure

Data was collected h m medical records to describe the sample including: gender,

birthweight, gestational age, presence or absence of bronchopulmonary dysplagia,

presence of hauterine growth retardation, number of days of mechanical ventilation,

and the presence and severity of intraventricular hemorrhage, penvenû-ïcula.

leukomalacia and echodensities derived from serial ultrasound recordings taken during

the neonatai penod.

The children are assessed on the MAP and the VMI at or about 4 years-corrected

age, (calculated by subtracting the infants' gestational age fkom 40 weeks and subtracting

this h m the child's chronological age) in follow up c h i c by one of two occupational

therapists. The therapists were aware that the children are neurologically normal in so far

as they did not have a diagnosed neurological condition (eg. cerebral paisy). The

assessrnent required approximately 60-90 minutes and the children were given breaks as

requested. Testing was discontinued if the child no longer wished to participate.

DATA ANALYSIS

Descriptive statistics (means, standard deviations, fkquency counts) were

calculated on al1 the variables. ANOVAs and Chi-squares tests were used to compare the

groups on the medical status variables.

Little research has been done to examine the effects of brain insult in the neonatal

period on the developmental functioning of extremely low birthweight chiidren at

preschool age who do not have a diagnosis of cerebral paisy. Even less has been done to

explore how the varying degrees of early brain insult impact on the later functioning of

these extranely low birthweight children. Since it is uaclear which groups of children

representing different severity of bleeds will differ in their performance h m children

without bleds, as well as fkom each other, the possibility exists that important

distinctions may be rnissed when an overall diffemice is sought among the groups as a

precursor to testing for more specific différences. In such an analysis a lack of

di fferences between some groups may cancel out ciifferences that exist between other

groups. For example, the most severe group may differ fkom the group without a bleed,

while groups with less severe bleeds may not differ. Likewise, among the groups with

bleeds, the extrerne groups (i.e. mild versus severe bleeds) rnay differ fkom each other,

but not firom the intexmediate group. Accordingly, consistent with an approach that is

more exploratory in nature, t-tests were used to make cornparisons between each of the

groups havuig bleeds (i-e., Groups B, C, and D) and the group with no bleeds (i.e., Group

A), as weil as to compare the groups with bleeds to each other.

Chapter 4

4.1 Cornparison of Groups on Medical Status Variables

Descriptive statistics (meam, standard deviations, hquency counts) are provided

on aLi of the medical status variables for the entire sample and for the four brain insult

groups. ANOVA and Chi-square analyses were conducteci to determine if the four

groups differed on any of these variables (see Tables 1 and 2). There was no signifiant

difference among the groups for birthweight [F(3,81) = .25, p = -861, mean gestational

age [F(3,8!) = 2 . 0 , ~ = .12], the number of days ventilatecl [F(3,76) = .90, p = -441, the

proportion of small for gestational age Sauts in each group [ A'(3,8 1) = -92, p = 321, nor

the incidence of bronchopulmonary dysplagia [r'(3,8 1) = 5.95, p = .I l] . Gender [ x2(3 ,8 1)

= 8 . 9 2 , ~ = .03], is the only variable found to be significantly different among tLe fou;

brain insult groups.

The outcome variables were examined based on gender using t-tests, no

significant gender difference in performance was found on the Nonverbal [t(77) = -.6S,

p = .52] or the Complex Tasks [t(79) = - 1.32, p = .19] Index of the Miller Assesment for

Reschoolers (MAF) or on the Beery VMX [1(70) = -.45, p = .65]. Therefore the

remaining analyses did not take gender into account.

Table 1

Means. Standard Deviations and Tests of Sinnificance for the Conîinuous Medical Risk Variables

Group

Birihweight 852.3 104.8 852.6 104.0- 833 144.1 866.7 116.5 .86 (gnuns) Gestational 27.3 2.3 26.3 1.6 26.3 1.3 26.2 1.5 .12 Age(w=W Days 36.8 29.7 29.4 20.1 36.8 21.7 41.7 22.7 -44 Ventilated

Note. A = No Insult, B = YII htnwentricular hemorrhage, C = m/TV Ineaventricular Hemonhage, D = Periveneicular Leukomalacia/Echodensities.

Table 2

Freuuencv Counts. Percentag:es and Tests of Sijznificance for the Discrete Medical Risk

Group

SGA 4 18 2 19 2 10 2 f 1 -82

RPD 7 32 13 56 9 47 12 66 -1 1 Note. A = No Insuit, B = VII Intraventricuiar hemonhage, C = III/IV Intraventricular Hemorrhage, D = Periventncular ~eukomalacial~chode~~~ities, SGA = Small for Gestational Age, BPD = Bronchopulmonary Dysplagia

4.2 Cornparison of Performance Outcornes between Brain Lesion Groups and the

Group with No Br& Lesion

It was hypothesized that e m e l y low birthweight children with brain insults

would perfom signincantly more poorly than those without brain insults, specifically

that children in groups B, C, and D would each show signincantly poorer performance on

the outcome meamres than those in Group A.

Group means and standard deviations for the percentiles and standard scores on

the MAP Nonverbal and Complex Tasks Indices and the Beery VMI are srlmmarized in

Table 3. The fiequency counts (percentages) for the MAP rkk categories are summarized

in Table 4. The fiequency distrrLbutions for the MAP ri& categones are presented in

Figures 1 and 2.

4.21 Grou0 Com~arisons of MAP Percentiles and VMI Standard Scores

T-tests were used to compare the MAP mean percentile scores and the VMI

standard scores of cach group of children with brain insults (Groups B, C, D) to the mew

score of the group of children with nomd head ultrasounds (Group A). Significant

differences in mean percentile scores are observed between the children with the most

severe insult, namely those with periventricular leukomalacia &or periventricular

echoes (Group D) and the nonnal preterm group (Group A) on the MAP Nonverbal Index

[t(33) = - 1.97, p = .05], as well as on the Beery VMI siandard score [f(35) = -2.60,

p = .01], with Group D scoring more poorly than Group A on both measures. However,

on the MAP Complex Tasks Index [t(36) = -1 -63, p = . I l ] , there was no significant

difference between the mean percentiles of Group D and Group A. Children with grades

III and IV intraventricular hemorrhage (Group C) did not perfonn significantly more

Table 3

Means and Standard Deviations of Percentiles for the Milfer Assessment for Preschoolers @fAP) Indices and of Standard Scores for the Beerv Test of V i s d Motor Intemation fVMn for the Four Brain Insult Grours

Group ------ -

A B C D TOTAL (n = 22) (n = 23) (n = 19) (n = 18) SAMPLE

....-.... ..- --* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... ...........

-...,..---.-... -..,.---...-.-Pd- -..-SR-- -.-M. SD .....-,. Al - . - SD - . . M SR. ..M SD ...... ....- ............ ......... ..... . .

Nonverbal 74.2 31.6 61.3 35.8 55.7 36.1 52-1 37.8 61.4 35.6 Index (%de) ComplexTasks 53.5 34.7 46.8 36.9 40.1 29.8 35.6 34.9 44.63 34.14 Index(Y0i1e) BeeryVMI 106.2 10.7 100.8 14.2 101.9 13.4 97.11 11.3 101.7 12.7 .- Note. MAP scores are expresseci as percentiles and VMI scores are express& as standard scores with an x of 100 and SD of 15. A = No h u i t , B = VII Intraventricuiar hemorrhage, C = UI/IV htraventricular Hemorrhage, D = Periventricuiar LeukomalacialEchdensities, MAP = Miller Assessment for Preschoolers, Beery VMI = Beery Test of Visual Motor Integration.

Table 4

Percenmes of Miller Assesment for Preschoolers (MAP) Index Scores for Risk

.. - -- . - . - Nonverbal Index

Nonnal At Risk Highest Risk Combineci Risk

Complex Tasks Index

Normal At Risk Highest Risk Combined Risk

D TOTAL (n = 18) SAMPLE

- ------ - Note. A = No Insult, B = VII Intraventncdar hernorrhage, C = UUTV Intraventricdar Hemorrhage, D = Periventncular Leukomalacia/Echodemities, MAP = Miller Assessrnent for ~Prescholers, Beery VMI = Beery Test of V i d Motor Integration. Normal = scores > 25%, At Risk = scores between 6-25%, Highest Risk = scores at or < 5%- Combined Risk = At Risk + Highest Risk = scores at or < 25%.

Figure 1: Freqwncy Distribution of MAP Nonverbal Index Risk Category Scores for Brain Insult Groups

Group C Group A Group B

Brain Insult Group

Group D

O "At Riskm (between.4th and 25th percentile)

a "At Highest Risk" (aî or below 5th perc-w "Cornbined Risk" (at or below 25th percentiie)

Figure 2: Frequency Distribution of MAP Complex Tasks hdex Risk Category Scores for Brain I n d t Groups

"At W" (between 6th and 25th percentile)

"At Kgksi Rkk" 1 (at or bdow 5th percentiie)

"Combined Risk" (at or beiow 25th 1 percentile) 1

Group A Group B Group C Group D Brain Insult Group

pooriy than Group A on the M M Nonverbal Index [f(36) = -1.73, p = -091, the Complex

Tasks Index [t(38) = -1.32, p = .19], or the Beery VMI [f(30) = -1 -09, p = .28]. The

differaices in mean scores were also not signincant between the mildcst uisult group

(Group B) and Group A on the MAP Nonverbal Index [t(42) = -1 -27, p = -2 11, the

Compiex Tasks Index [t(42) = -.63, p = .53], or on the VMI [t(39) = -1.43, p = -161.

4.22 Com~arison of Groum on the MAP Risk Caîe~ories

The percentile scores for aU the groups f d in the nonnal range (i-e. above the

25th percentile) on the MAP (see Table 3). The analysis was fbther refined by

examlliing the percentages of children in each group that fell into the risk categories.

According to the author of the Miller, risk scores reveal more clùiically meaningfbl

idonnation than percentiles.

Differences in the categoncal scores (Le. normal, at nsk, and at highest nsk) by

brain insult group were analyzed using a t-test of significant differences between two

independent proportions in order to detennine if each of the groups with brain insults

(Groups B, C, and D) exhibited a higher proportion of children in the nsk categories than

the group without insults (Group A). There was a significant Merence between the

children with normal head dtrasounds (Group A) and the children with periventncular

leukomalacia andor periventricular echoes (Group D) on the MAP Complex Tasks

Index. A significantly higher proportion of the children with periventricular leukomalacia

andor periventricular echoes scored in the "at highest risk" category [t(39) = 2.5,

p = -021. There was no significant difference between these two groups on the

proportion of children who scored in the "at nsk" category [ t(39) = .18, p = .4]. On the

MAY Nonverbal Index the children in Group D did not differ significantly h m the

children in Group A for the "at highest nsk" categnry [t(39) = 1-65, p = -101, or the "at

risk" category [1(39) = -80, p = .30].

Tbere were no significant clifferences in risk category membership between the

children in Group C and the children in Group A. For the Complex Tasks Index, the

proportion of children in highest risk" category in Group C was not significantly

higher than for Group A [t(40) = .29, p = .40], nor was the proportion of Group C

children in the "at ri&' category [t(4û) = .09, p = .40]. For the MAP Nonverbal Index,

no children in either Group C or A were wnsidered to be in the " at highest risk"

category, and the proportion of children in the "at risk" category in Group C was not

significantly higher than in Group A [1(40) = 1.23, p = -181. The proportion of children in

Group B al50 did not differ significantly fkom the proportion of children in Group A who

were considered to be in the "at highest nsk" category on the MAP Complex Tasks index

[t(44) = 1.12, p = .21], or those considered to be in the "at risk" category on this Index,

[t(44) = .45, p = .36]. The same results were obtained on the MAP Nonverbal Index for

the "at highest nsk" category [t(44) = 1 .O, p = -241, and for the "at risk" category [t(44) =

1 .O, p = -241 when Group B was compared to Group A.

This hypothesis was partiaily upheld; the mean percentile scores for the children

in Group D were significantly lower on the MAP Nonverbai Index and on the Beery VMI

than those of the children in Group A. The mean percentile scores of the children in

Groups B and C were not significantly lower than those of Group A on any of the three

outcorne measures. Al1 of the groups, however, achieved mean scores in the normal

range. When the scores are examined according to which groups of children exhibit

scores in the risk ranges for the MAP, a trend toward poorer pdormance as brain Uisult

swerity inmeases, is observed, but statistically sigdicant ciifferences are only seen

between the most severe group (Group D) and the group with nomid head ultrasounds

(Group A) on the Complex Tasks Index, with more children in Gmup D falling into the

'kt highest ri&" category.

4.3 Cornparisons of the Groups with Dinerent Sevetity of Brain Insult on the MAP

Index Percentiles and the VMI Standard Scores

t was hypothesized that the severity of periveniricular brain damage would

correlate negatively with MAP and VMI performance: the greater the insult the poorer the

perfixmance. Among the children with bleeds, it was anticipated that group D would

perform significantly more poorly than groups C and B, and that group C would perform

more poorly than group B.

The MAP percentile scores and the Beery VMI standard scores were analyzed

using t-tests to compare the p . p s tozach other. There were no significant différences

in mean percentile scores between Group B and Group C, on the MAP Nonverbal Index

[f(38) = -5 1,p = .61], the Complex Tasks Index [t(39) = -65,p = .52], or on the standard

score of the Beery VMI [t(35) = -.24, p = .8 11. The mean scores of Group D also did not

ciiffer significantly h m the mean scores of Group C on the MAP Nonverbal Index

[t(34) = -.29, p = .77], the Complex Tasks Index [1(33) = -.43,p = .67], or the Beery VMI

[t(3 1) = - 1.14, p = .26]. Likewise the ciifferences in mean scores between Group D and

Group B did not reach statistical significance for any of the three measures: MAP

Nonverbal Index [t(35) = -79, p = .43], the Complex Tasks Index [1(37) = 1.01, p = -321,

or the Beery VMI [t(37) = .92,p = -361.

4.4 Cornparison of the Groups with Diflerent Severity of Brain Insult on the MAP

Risk Categories

T-tests for proportions comparing groups B, C, and D on the MAP risk categones

show that Groups B and C, C and D, and B and D, did not diffa significantly in terms of

the proportion of children scoring in the "at risk" category (between the 6th and 25th

percentiles) or the "highest risk" category (at or below the 5th percentile). The proportion

of children in Group C and Group B in the "at highest risk" category on the Nonverbal

Index [t(41) = -86,~ = 271, and the "at risk" category [t(41) = 1.17, p =.20], was not

significantly différent, This was aIso tnie of the Complex Tasks Index for these two

groups for the "at highest risk" category [t(41) = .21, p = .39], and the "at risk" category

[t(41) = .55, p = .34]. The difference between the MAP Nonverbal scores for Group D

and Group C that fell hto the "at highest risk" category [t(36) = -49, p = .35], and the 'kt

nsk" category [t(36) = -1 1, p = -401 was also not significantly different. The scores on the

Complex Tasks Index for Group C versus Group B considered to be in the "at highest

risk'kategory [t(36) = S 3 , p = .35], and the "at risk" category [t(36) = .37, p = -401 were

aiso not significantly different. Between Group D and Group B on the MAP Nonverbal

Index, the proportion of children that fell in the "at highest risk" category [f(40) = -89,

p = .27], or in the "at risk" category [t(40) = .81g = -291, was not significantly different.

For the Complex Tasks Index, the proportion of children in these two groups that fell in

the "at highest nsk" category [t(40) = 1.67, p = -1 O], or in the "at risk" category

[t(40) = .50, p = .35], was also not significantly different.

52

Therefore this hypothesis was not upheld, the sevaity of the brain insult did not

relate to performance on the Nonverbal and Complex Tasks Indices of the MAP or on the

Beery VMI, either for the cornparisons of percentiles, N k category scores or standard

scores.

Chapter 5

DISCUSSION

This study sought to detennine if children bom weighùig less than 1000 gram are

at risk for pre-academic problems at preschool age. The children assessed in this study

were dl without neurological disabilities (eg. cerebrai palsy) and without spedic sensory

handicaps. Most of these children, despite being born at extremely low birth weights and

gestational ages and having prolonged hospitalizations with numerous interventions, are

generally fûnctioning at comparable levels to their comted age peers on assessments of

visual percepiuai, visual spatial, visual-motor integration, memory, and motor planning.

Eighty-three percent of the cohort achieved percentile scores in the nomal range on tests

of memory, performance and sequenckg (MAP Nonverbal Index). Sixty-seven percent . scored in the n o d range on items requiring the combination of sensory, motor and

cognitive abilities for the interpretation of visual spatial information ( M M Complex

Tasks Index). AI1 children achieved scores in the nomal range on a test of visual motor

integration (Beery VMI). Thus extreme premahirity, in and of itseIf. does not appear to

lead to deficits in pre-academic skills, at least those that are not language based.

The only differences obtained were between children with bleeding into the white

matter of the brain or injury to cerebral tissue from lack of oxygen (Group D), and

children with no insults on head ultrasound (Group A). The poorer performance of

Group D reached significance compareci to the performance of Group A for the percentile

scores of the Nonverbal Index of the MAP and the nsk category scores of the MAP

Complex Tasks and on the Beery VMI. Children with bleeding that is restricted to the

lining of the ventricles or the ventricles themselves (Groups B and C) did not perform

significantly more poorly on any measures than the normal preterm children. Of interest,

however, is the decreasing trend among the groups in mean percentile scores. The

normal children (Group A) achieved mean percentile scores of 74.2 on the Nonvexbal

Index and 53.5 on the Complex Tasks Index, the children with grades 1 and II

intraventricular hemorrhage (Group B) attained mean percentiIes of 6 1.3 on the

Nonverbal Index and 46.8 on the Complex Tasks Index. For Group C, the children with

grades JII and ni' intraventricular hemorrhage, the mean percentile scores were 55.7 on

the Nonverbal Index and 40.1 on the Complex Tasks Index and for Group D, the chiidren

with periventricular leukomalacia or peIiventricular echoes, the mean percentiles were

52.1 and 35.6 respectively. Thus, even though the chikiren ail achieved scores considered

to be in the nomal range the presence and extent of periventricular brain insult may, in

fact, negatively influence these children's ability to intapret and manipulaie the kind of

information assessed by the Nonverbal and Complex Tasks M c e s of the Miller

Assessment for Preschoolers.

The poorer performance exhibited by children with periventricular injury could

not be aitributeci to severity of iIlness during the neonatal period Respiratory status,

gestational age, birthweight, and small for gestational age status did not Vary across the

groups. The groups did differ in terms of gender, but the test scores did not reflect a

significant ciifference by gender. Snider (1996) found that boys performed more poorly

on the Nonverbal and Complex Tasks Indices of the MAP at three year of age, but a

gender difference on those tasks was not replicated in this study for childrm at four years

of age. Perhaps the extra year had allowed the males to catch up to their female

counterparts. More exposure to these types of activities fiequently occurs in nursery

school or day care settings, and thus experience and practice may account for improved

performance at four years of age.

Despite pafomiing signincantly more poorly on tasks of visual perception,

memory, visual spahial manipulation and motor planning than children without brain

insult (Group A), most children with periventricular leukomalacia and/or periventricular

echoes (Group D) still performed in the nomal range at four years of age. It is possible

they are able to manage the skills that are appropriate at this age, but may eventually no

longer be able to cope when ta& complexity fiuther increases. Their difficulties,

therefore, may become more apparent as tasks becorne more challenging. Investigators

have found that by school age, very low birthweight children do have difficulties with

visually mediated tasks such as spatial relations and matching (Klein et ai., 1989) and

memory (Abel-Smith and Knight-Jones, 1990, Hack et al., 1992, and Ross et al., 1991).

The mean standard score on the Beery Test of Visual Motor Integration was also within

normal limits for Group D. The group of children with normal head ultrasounds scored

significantly above the mean on this measure and the children in the other groups

performed around the mean. Once again, however, there was a significant difference

between the children with normal head ultrasounds (Group A) and the lower scores

obtained by the chi1dren with periventricular leukomalacia andfor penventrïcular echoes

(Group D). Again, many investigators have found that premahae, extremely low

birthweight children perfonn poorly on tests of visual-motor integration at school age

(Hack et ai., 1992; Klein et al.; Saigal et al., 1991). The Beery VMI meaSuTes the ability

to copy increasingly complex geomeûic figures. The normal scores found for Group D in

the present study, may reflect once again the simple nature of tasks at this age. As the

children get older and the figures become more difficult and increasingly wmplex

integration is required, deficits may become more apparent. At younger ages, when the

demands of the task are not as gre* a child having a brain insult may still be able to

compensate.

The Miiler Assessnent for Preschoolers (MAP) is designed to identiQ children

who are not overtly abnormal, but who are at risk for academic difficulties. It is

especially designed to discrimlliate among children whose scores are low. Therefore

reviewing the data based on risk-group membership helps to clariQ the findings for the

MAP percentile scores, which were in the normal range for all of the groups. The risk

categories identify the particular children within each group who represent a risk despite

the overall nomal performance of theii gmiip.

There is a trend for more children to score in a risk category on the MAP as the

severity of the brain injury inmeases. Although the majonty of children with neonatal

brain damage fùnction in the normal percentile range, as the seventy of the brain injury

increases the percentage of children identifid as being at risk increases. When the sample

as a whole is examined, 17% of the entire cohort are considered to be in the "at risk" or

'liighest risk" category in the area of visual perceptual and memory skills (MAP

Nonverbai Index) and 33% in the area of visual spatial and motor planning abilities

(MAP Complex Tasks Index). If the percentages are examine& it is apparent that the

number of children in the two risk categories increases gradually with hcreasing sev&ty

of brain injury- Nine percent of the children with w evidence of perïvenaicular lesion

fd into the risk categories on the Nonverbal Tasks Index of the MAP, 13% of childm

with grades 1 or II intraventricular hemorrhge fd in the risk categories in this am, 2 1 %

of children with grades III or IV intraventricuiar hemorrhage and 28% of children with

periventncular leukornalacia W o r peziventricular echoes. On the Cornplex Tasks Index

of the MAP, 22% of the no insutt group are in the two risk categories, 35% of the Grades

I l i l intraventncular hernodage p u p and 26% of the Grades III/IV intraventricular

hemorrhage group. Of the children with periventricular leukornalacia andor

periventricular echoes, 50% of the cohort fd into the two ri& categones.

Only the differences between Group A and D on the MAP Complex Tasks Index

for the higkest nsk category is statistically significant Frisk and Whyte (personal

communication, 1994) also uncovered deficits on some, but not all, visual perceptual and

visual spatial tasks for six year old children with intraventricdar hemorrhage or

periventricular leukornalacia The children with mild or severe lesions had trouble

identifying missing details fiom pictures or recogniPng objects when presented as puzzle

pieces. They also had difficulty copying designs using blocks or pencil and paper. In the

present study, the children with mild Uisults did not, in fact, show these difficulties at

four years of age. The impact of the darnage to the periventricular area may become

more significant as the child gets older. Other studies relating head ultrasound lesions

and outcome on visual percephial and visual motor tasks have obtained similar findings.

Whitaker et al. (1996) found that at six years of age, those neurologically nomial children

with parenchymal lesions or ventncular enlargement perfonned sigdïcantly below

children with isolated genninal rnatrix hemorrhage on tests of visual perception and

visual-motor integration.

Injury to the developing brain in the neonatal period may have lasting effects for a

number of reasons. Intraventricular hemorrhage results in destruction of precursor cells

in the developing germinal matrix of the infant. The destruction of these cells may lead

to the elimination of the oligodendroglial cells, which are i m p m t for neuronal

myelination. Damage to the precursors of astrocytes intended for the upper layers of the

neocortex is also postulated to impair cortical development. Hemorrtiagic &or ischemic

lesions may interrupt projection and association fibers connecting various areas of the

brain and as well may damage neurons of the subplate that are cntical for neuronal

organizatio'ii in the cortex. The subplate neurons are considered to play a critical role in

cerebral organization. These cells receive inputs ascending fiom the thalamus and distant

cortical sites and extend collaterals to the cerebral cortex. The subplate neurons provide a

site for synaptic contact for axons ascending b m the thalamus and other cortical sites.

Subplate neurons are also thought to guide ascending axons to îheir targets in the cortical

plate. If the subplate neurous are eliminated cortical afferents may fail to move into their

appropriate sites in the cortex. A m e r function of the subplate neurons is involvement

in cerebral cortical organization. The subplate layer reaches a peak between 22 and 34

weeks gestation which corresponds with the times of occurrence of intraventricular

hemorrhage and perivenûicdar leukomalacia If' these insults disrupt the subplate neurons

it could interfere with the development of crucial neuronal connections and projection

systems and perhaps impact on cortical organktion and future cortical functioning

(Volpe, 1995). As well damage may 0ccu.r to ascending and descendhg axons in the

cerebral white matter thereby affecting the development of the cerebrai cortex (Evard et

al., 1992, Frisk and Whyte, 1994, Perhan, 1996, Volpe, 1995). These lesions may

therefore produce deficits in skills requiring the integration of information fÎom a variety

of sources.

Why children with periventricuiar insults experience difficulty with tasks

involving integration of information and ski& h m various domains may also be

explained by examiaing the particular area of the brain affecteci. The region of the brain

in preterm infants where bleeding or ischaemia most commonly occurs is in the area

sumunding the ventricles. This encompasses areas of the posterior hnta l lobes, the

parietai lobes and parts of the occipital and temporal lobes. Extensive interrelationships

among various sensory-motor systems, and the integration of incoming sensory

information characterize normal perceptud fùnction and Wtely takes place in the area

where bleeding occurs (Walsh, 1978). Injury to this area has been hypothesized to cause a

number of difficuities includuig spatial difficzilties,. visual-motor difficulties and short

terni memory problems. The temporal lobe is concemed with the integration of visual

experience with al1 f o m of incoming sensory information. The sensory-motor, motor

and motor association cortex, which are situated in the parietal and fiontal lobes, directly

mediate motor perfomance as well as the planning of motor programmes. The children in

this study with the most severe damage to the periventricdar region perform more poorly

on the measmes requiring the integration of cognitive, snisory and motor abilities but had

less difficulty with tasks that measure memory, visual perceptuai skilis and sequencing

more distinctly.

Using corrected or unconected age to interpret the d t s remains au important

issue. Scores for this whort were intaprcted according to wrrected age to allow for a

true identification of the deficits caused by central nemous system damage and not the

transient effects of prematurity (Landxy et al., 1993). The children with the most severe

insult to the periventricular region (Group D) c i i f f i fiam children with no insult

(Group A) on the MAP Nonverbal Index and not the MAP Complex Tasks Index when

percentiles where compared, but oniy on the MAP Compiex Tasks Index for the

cornparison of the nsk categories. Even though Group D perfonned more poorly on the

MAP Nonverbal Index, the fact that their mean percentile score were still in the average

range &es this result of less c l in id concern than the p a t e r incidence of "hi@ nsk"

performance shown by these children on the MAP Compiex Tasks Index. This area is the

aspect of their hctioning that requires the ciosest monitoring or tratment.

As well, the mean gestational age of the entire sample was approximately 26 weeks,

signifjring that most of the infants were bom 14 or more weeks prior to their due &te.

This degree of immaturity is thought to impact on fiuiction for fa- longer penods of t h e

than for infants bom at older gestational ages (Rickards et al., 1989). Using corrected

ages compensates for this and ensures that we are measuring the child's ability at the

time. Seigel(1982) found that ushg uncorrectecl age scores on developrnental

assessrnents better predicted long-term outcome. Her research however, was conducted

in the 1980's with preterm children boni at a mean gestational age of approximately 30

weeks. This ciifference in gestational age, with infants now being bom and surviving

without major deficits at younger ages, may be great enough to impact on long-term

outcome even when using corrected aga.

This study is Unportant to occupational therapists because the goal of occupationai

therapy treatment is to achieve a rehanent of the performance components (Le. sensory

and motor abilities) that may be required for age-appropriate hctional tasks, such as

self-care, play and completion of school work withui the home and school envkonments

(F~iefeld., Snider, and Phillips, 199 1). Improvements in the motor planning ability of

school age children with learning disabilities and sensory integrative dysfunction have

been found with the use of sensory integrative and perceptud motor therapies

(Humphies, Snider, and McDougall 1993, Humphries, Wright, Snider, and McDougaU,

1992, Humpries, Wright, McDougall and Vertes, 1990). Humphries et al., (1 990; 1 992;

1993) suggest that that postural reactions and motor planning are a basis for irnprovement

in eye-hanci coordination and form and space perception. Sensory integrative therapy

provides sensory experiences and encourages the child to make adaptive responses to

them to improve how the brain processes and organizes sensory input. Children

experiencing dificulties with cornplex tasks, those requiRng the integration of cognitive,

sensory and motor information as assased on the MAP, may therefore benefit kom these

typa of îherapies.

Humphries et al., (1992) found that sensory integrative therapy produced a

significant irnprovement in motor planning in children with leamhg disabilities and

sensory integrative dysfunction. They suggest that this may reflect the effect of overall

improved organization of sensory input on the sequencing of motor activities. The ability

of the brain to conceive, organize and carry out a sequence of dafniliar actions is

thought to be a prerequisite to acquiring fiulctional skills, and is presumably enhanced by

sensory integrative therapy. They also fond that the change in motor planning was

fond to correlate significantly with a change in motor performance at the academic level,

namely in printing readiness. Premaîure children with motor planning deficits, therefore,

rnay benefit h m this type of therapy.

Whether sensory integrative andlor perceptual motor therapy would improve the

later school performance of pretem chi1d.m with periventricular brain i n j q requires

fiutha investigation (Frisk and Whyte, 1994, Hack et al., 1994, Klein et al., 1985, Saigal

et al., 1990, 1991). Many underlying motor, sensory and percephmi deficits can interfere

with successfbl performance of academic skills such as reading, writing, and arithmetic.

Poor social skills development and poor seIfkoncept ofkn characterizes children with

learning difficuities and poor school performance. Knowing that children with

penventriciilar leukomalacia d o r periventncular echoa are at higher risk of having

difficulty with certain visual and motor tasks has implications for whether they receive

treatment and the type of intervention which may be most beneficial.

This study adds to the literature as it exaiaines'ihe performance of a relatively

large sample of extremely low birthweight children with varying degrees of

penventricular brain injury on measures of pre-academic fwictioning. Investigators have

examined the functioning of low birthweight children at school age (Abel- Smith and

Knight-Jones, 1990, Hack et al., 1992, Halsey et al., Klein et al., Saigal et al., IWO, 199 1,

Ross et al., 1991). Others have looked at the preschool performance of extremely low

birthweight children (Costello, Hamilton, Baudin, Townsent, Bradford, Stewart and

Reynolds, 1988, Ellison, Petersen, Goman, and Sharpsteen, 1992, Haisey et al., 1993,

Klein et al., 1985, Weisglas-Kuperus, Uleman-Vleeschdrager, and Baerts, 1992). Very

few have examined the specific effects of periventricular brain i n j q on preschool

performance of neurologicaliy normal pretemi children.

Chapter 6

Limitations of the Study

A main limitation of the study is the lack of a full-tenn conhPl group. m e a d the

group of preterm cIiildren without bleeds was used as a cornparison group. This study is

aiso retrospectivc and, as such, some information about the participants was not available.

The actuai Bayley scores h m the children's two year cognitive assessrnent were not

available and the distribution of IQ's across the groups is therefore tubown. However

al1 children had to be in the average or below average range to receive the testing* and not

have a signifiant cognitive delay. The occupational therapist wessing the children at

four years of age would have had access to the medical chart and information on the

children's head ~Itrasounds. She muld, there fore, be aware of the cbild's brain lesion

statu but not be aware of the groupings or the actual design used in this study.

Information was not collected on the home environment of the children in the cohort or in

each group. As a d e , though, the follow up clinic population reflects the population of

greater Toronto with no one ethnic or cultural group being over represented. As well, no

data was collected on early intervention services provided to the children or the types of

activi tieslprograms in which they padcipated. Therefore the influences of the

environment a d o r other factors that may have afkcted the performance of the children

on the assessments is not known.

Follow up of these children at school age to determine if preschool performance at

four years of age is related to performance at school age would fùrther assist in the

planning and designs of their programming.

Conclusion

This study supports the assumption that minimal brain damage in the early

neonatal period is not a benign event for some extremely low birthweigùt preterm infants.

Subtle damage to the developing nervous system appears to have an impact on

functioning in a number of performance domains for some of these children. Children

with more severe periventricuIar damage, in particular need to be followed carefully into

preschool and school age. The areas assessed m this study are components of hture

academic and other occupational skills and therefore early intervention may prevent

ongoing pmblems. As resources become more stretched, focushg the preschool follow

up of extrmely low birthweight infants on those with intraventricular bleds wiil

maxi-e resources while minimizïng the risk that children with such difficulties are

missed.

GLOSSARY

Acidosis

Alveoli occm

Apnea

Asphyxia

Astroc yte

Atelectasis

Axon

B arotrauma

Bilinibin

Bradycardia

- an excess of acid in the blood and body tissues

- terminal dilations of the bronchioles of the lungs where gas exchange

- absence of breathing

- lack of oxygen and blood flow

- a type of neural glial ce11

- a collapsed condition in part of the lung

- projection of a neuron conducting impulses to other neurons or to muscle fibers and gland cells

- damage to the lungs caused by pressure ventilation

- a yellowish substance produced when red blood cells break down

- slower than normal heartbeat rate

Bronchopulmonary Dysplagia - chronic respiratory disease thought to be caused by oxygen toxicity and barotrauma resulting fiom pressure ventilation

Cerebrospinal Fluid (CSF)

Coronal - cross-section

Ductus Arteriosus

- fluid produced in the ventricles of the brain that circulates around the brain and spinal cord

- a blood vessel in the fetus that joins the aorta with the pulmonary artery in order to divert most blood away from the fetal lungs. This blood vessel must close after birth so blood can flow properly to the lungs to receive oxygen

Echodensities - areas of increased attenuation (density) on ultrasound (appearing darker)

Ependymal - the cellular membrane Iining the central canal of the spinal cord and the brain ventrides

- the cellular structure present at the fetal stage of brah development that giva rise to the structure present in the neonate

Gestation - the length of time between the first &y of the mother's last memtrual period before conception

Glial cells - the interstitial or accessory celis of the central nervous system

GIiosis - death of the glial cells

- an abnomai accumulation of CSF in the ventricles of the brain causing enlargement of the ventricles

Hyperbilirubinemia - excess bilinibin in the blood eg. Jaundice

Hypararbia - an excess of carbon dioxide in the blood

Hypovolemia - an abnormally low volume of blood in the body

Hypoxia - sub-optimal levels or oxygen in blood, tissue

Interhemispheric fissure the brain

- the space between the two main hemispheres of

Ischaemia - ce11 death due to lack of blood supply

Intraventricu f ar - within the lateral ventricles of the brain

Lateral ventticle - horseshoe shaped cavity located in the midline of each cerebral hemisphere where CSF is made

Myelin - the layers of lipid and protein substances cornposing a sheath around nerve fibers

Necrosis - pathological death of one or more cells, or of a portion of tissue or organ

Necrotizing Enterocolitis - a gangrene like condition of the intestinal tract

Neurodevelopmental - skiil repertoire relating to neurological maturation

Parasagiittal - in a plane dividing the body into left and right sides

Patent Ductus Artenosus - an abnormal condition in which the ductus in the heart fails to close after birth

Perinatai - pertaining to the period of t h e during and just d e r the t h e of birth

Periventricular- the area around the lateral ventricle of the brain

Periventncular Leukomalacia - ischaemk event characterized by necrosis of the brah tissue in the region surrounding the ventricles due to lack of blood supply

Retinopathy of premaîurity - an eye disease thought to be causai by abnomial growth of the blood vessels in the eye

Subependymal- the area just beneath the lining of the ventricles

Ventricular System - maIl chambers in the centre of the braiu where cerebrospinal fluid is made

I b

55s UN-rn AvaJuE m ~ o m . -A MX; ow..~. 1x8 THE H O S P m FOR SICK C H J J D m PHONE (4 16) 813-1500

RESEARCH ETHICS BOARD

Ms. Suzanne Breton Department of Rehabiiitation Services The Hospital for Sick Children

September 26.1997

Dear Ms, Breton

Further to your request, I am writing to confinn that your study "The Effects of Penvenuicular Brain Injury on the Motor and Vïud Motor Abiliûes of Childrcn Born Weighing Under lOOOg at 4 Years of Age" which 1 understand is a retrospective chart review, where there is no patient contact, and where data wiil be reported annonymously does not require REB review.

You should note. however, that this situation will probably change following the release of the new Code of Ethical Conduct for Research Involving Humans in early 1998. It is expec3:d that the Code will require REB approval of secondary use of dl data tbat includes identiQing information. and in some instance will require participant informeci consent

Yours tmly

Aideen Moore, MD, MRCPI, Chair, Research Ethics Board

FRCPC

A l i a i c h cuc. ~eaching and

rcsctrch centre dcdiated aclusivcly to dddren;

fi~lutcd with the

Univcniry of Toronto

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l MAGE NALUATION TEST TARGET (QA-3)

APPLIED 4 IMAGE . lnc 1653 East Main Street -

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