TITLE OF THE JOURNAL

Authors & Reference

Presenter : Phinoj K. Abraham MOTh(Neurosciences)

OBJECTIVES

To discuss the findings of recent original research article on eye-

hand coordination in stroke survivors while sitting and standing

and its relationship with sensorimotor performance.

To critically analyze this scientific paper

To discuss the clinical implication of the study findings in our

setting

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Key Terms

• Finger Pointing

• Stroke

• Sensorimotor Impairments

• Postural Stability

Abbreviations

• FRT – Functional reach Test

• TUG – Timed-up-and-go test

IntroductionBackground

• Eye-hand coordination is involved in any visually

guided, goal-directed use of the hand

• It is crucial for reaching for and manipulating the tools

of daily activities

• Coordination among vision, limb proprioception, and

movement of the shoulder, elbow, wrist, and fingers is

essential for successful reaching

• Postural stability is the ability to integrate sensory

information from the proprioception, visual, and

vestibular systems to make the motor responses

needed to maintain the center of gravity within the

base of support

• Good postural stability is extremely helpful in

performing many of the activities of daily living.

IntroductionBackground

IntroductionLacunae of research

• Most investigations of eye-hand coordination have

been performed in a sitting position, which involves

less demand for postural stability, so the

interrelationship between eye-hand coordination and

postural stability is not very clear

IntroductionNeed of the study• Stroke often induces persistent sensorimotor impairments

such as muscle weakness, poor proprioception, and

impaired upper extremity function.

• Often, eye-hand coordination and postural stability are

also degraded.

• A better understanding of the relationships among all

these sequelae promises to help in the design of

rehabilitation interventions

Aims of the study

1. to examine the effects of stroke on eye-hand

coordination with a concurrent postural stability task

2. to study the relationship among sensorimotor

performance, eye-hand coordination, and postural

stability

MethodologyResearch Design

• Cross sectional study

MethodologySampling• Sample population– community-dwelling stroke survivors• (9 men and 6 women; mean [SD] age, 58.7 [7.5]

yrs)

• Sample Size– 15

• Sample Procedure– Convenient Sampling

MethodologyInclusion Criteria

1. MMSE of at least 24

2. Snellen visual acuity of at least 20/40 (with or without

any visual correction device)

3. Shoulder flexion of at least 90 degrees,

4. Lack of elbow extension not more than 30 degrees,

5. Wrist extension at least 0 degrees, and

6. Able to stand independently

MethodologyExclusion Criteria

1. hemianopia (using Star Cancellation test),

2. visuospatial neglect (using Rapid Confrontation

Screening test)

3. amputation of the index finger, and

4. Ashworth Scale scores 3 or above for upper and

lower limbs

MethodologyMaterials & Methods

• The subjects underwent the following

assessments:

1. knee proprioception,

2. muscle strength,

3. balance, and

4. eye-hand coordination.

• The subjects’ knee proprioception was

assessed using a validated limb-matching task

• The subjects were instructed to move their

paretic leg to a position somewhere in the

midrange of normal joint excursion, then move

the non-paretic leg to the same position as the

paretic leg. (with eyes closed)

Assessment of knee proprioception

MethodologyMaterials & Methods

MethodologyMaterials & Methods• Assessment of muscle strength– the shoulder flexors, elbow flexors, wrist extensors,

quadriceps, and hamstrings were tested with a Nicholas handheld dynamometer

• Assessment of Balance– Functional reach test

• Assessment of eye-hand coordination– fast finger-pointing task

• Functional Mobility– Timed-up-and-go test

• Subjects were instructed to use their index fingers to touch a moving target appearing on a visual display unit, contralateral side to the arm being tested– In sitting– In standing

• the upper edge of the screen was at the subject’s eye level• the distance between the screen and the subject was equal

to the subject’s arm length• An accelerometer was fixed to the subject’s ulnar styloid

process – to assess the reaction time

Assessment of eye-hand-coordination

MethodologyMaterials & Methods

• Subjects were instructed to touch the target as quickly and accurately as possible

• The task was performed – 10 times in sitting – while sitting in a non rotating chair with

backrest– 10 times in standing – while standing barefoot on a force plate

• The sequencing of the Ax was as follows: pointing with1. the unaffected arm while sitting2. the affected arm while sitting3. the unaffected arm while standing, and4. the affected arm while standing

Assessment of eye-hand-coordination Contd..

MethodologyMaterials & Methods

• The protocol produced repeatable results with healthy

elderly subjects,1 and the methodology has been used to

study the eye-hand coordination of stroke survivors in a

previous study.2

Assessment of eye-hand-coordination Contd..

MethodologyMaterials & Methods

1. Gao L, Ng SM, Kwok WY, et al: Eye-hand coordination and its relationship with sensori-motor impairment in stroke survivors. J Rehabil Med 2010;42:368Y73

2. Kwok JC, Hui-Chan CW, Tsang WW: Effects of aging and Tai Chi on finger-pointing toward stationary and moving visual targets. Arch Phys Med Rehabil 2010;91:149Y55

Operational Definitions• Reaction time was the time between the appearance of the

moving visual signal on the screen and the onset of arm

movement

• Movement time was the time from the onset of arm

movement to touching the visual target.

• Accuracy was the absolute deviation of the touch position

from the center of the target at the moment of touching.

Outcome Measures

• To Assess

– Reaction Time : Accelerometer

– Total Sway path and displacement : Force plate

Statistical Analysis

• To Check Normality : Kolmogorov-Smirnov test

• To compare reaction time : paired ‘t’ test

• To check the correlation between the knee proprioception,

muscle strength, hand grip strength, functional reaching and

TUG (time Up and Go test) results and performance in the fast

finger –pointing task : Pearson r– SPSS software version 17 was used for computation

– Significance threshold was set at 0.05

ResultsEye-Hand Coordination Performance

1)

2)

3)

4)

Rea ction Time

St anding

Pare tic Si de

Non Pare tic Side

Movement T ime

Sit ting

Pare tic Si de

Non Pare tic Side

Movement T ime

St anding

Pare tic Si de

Non Pare tic Side

Avg. Movement Time

Sitting

Standing

P = 0.026

P = 0.001

P = 0.001

P = 0.045

ResultsPostural Stability

Total Sway

Standing

Paretic Side

Non Paretic Side

P = 0.009

AP Displacement

StandingParetic Side

Non Paretic Side

P = 0.002

AP : anteroposterior

ResultsCorrelations

• There was significant negative correlation between

1. Movement time on paretic side while standing vs.

functional reach score

2. Movement time – while sitting & standing vs. Hand grip

strength

3. Movement time while sitting vs. wrist extensor strength

4. Shoulder flexor strength Vs. accuracy in sitting

• There was, however, no significant correlation

between eye-hand coordination and

1. postural stability, (Assessed with FRT)

2. TUG times,

3. knee proprioception, or

4. leg strength

ResultsCorrelations Contd..

DiscussionEffect of stroke on Eye-Hand coordination Paretic Side vs. Nonparetic Side – Reaction Time

• FINDING: Slower Reaction time – with paretic arm

– during finger pointing task – while standing Previous study reported that stroke survivors have

slower VERBAL reaction time in sitting vs. standing –

due to ‘dual task paradigm’ (Brown et al, 2002)

‘…in this study, slower reaction times in the finger-

pointing task’

• FINDING: The paretic side had a longer movement

time than the non-paretic side – in sitting and

standing

– Impaired isolated movement (Zackowski KM,2004)

– Abnormal joint torque production (Dewald 2001)

– Impaired joint coordination (Cirstea 2000)

– Less flexible joint after stroke (Reisman 2003)

DiscussionEffect of stroke on Eye-Hand coordination Paretic Side vs. Nonparetic Side – Reaction Time

• FINDING: In this study, some subjects used trunk

displacement as a kind of compensatory strategy in

the fast finger-pointing task when standing.

• This shortened the distance to the moving visual

target, so the movement time was shorter when

standing than when seated.

DiscussionConcurrent postural stability and Eye-Hand coordination Sitting Vs. Standing – Movement Time

• FINDING: ….the total sway path and AP displacement

increased when the subjects reached for a moving visual

target with their paretic arms– Stroke survivors shows decreased anticipatory

activation (Shumay-cook 2007)

– Attention capacity is decreased after stroke (Marshal 1997)

– The resources allocated to postural stability were reduced when the subjects had to tackle an attention-demanding concurrent task. (Bensoussan L, 2007)

DiscussionTotal sway path and Anterior Posterior Displacement

• FINDING: There was no significant correlation between

movement time and shoulder flexors strength found in this

study

– There are 2 movement strategies in fast finger pointing,

Deltoid and Biceps Brachii Strategies

– Post-stroke subjects normally have elbow flexion at the

beginning of reaching

DiscussionSensorimotor Performance and Eye–Hand Coordination Limb Function

• FINDING 1: Faster movement time on the paretic side was

associated with better forward reaching in the standing

position. – This indicated that better balance might be helpful for fast finger-

pointing.

• FINDING 2: there was no relationship found between

pointing speed and TUG times. – A TUG task might challenge subjects’ functional mobility, but it

was not specific enough to relate to quiet standing.

DiscussionBalance

Clinical Relevance

• Postural stability was found to affect the

performance of eye-hand coordination in terms of

both reaction time and movement time

• Therefore, the rehabilitation of stroke survivors

should not be confined to a stable posture such as

sitting

Clinical Relevance

• Rehabilitation can be geared toward using the

trunk strategy to enhance upper limb performance

during different postural tasks.

• Conversely, restraining trunk movement might be

used to reintroduce the normal movement pattern

for reaching.

Limitation of the study• Small sample size

• Used convenience sampling

• Information about the kind of stroke or the site of the lesion was not collected

• Stroke survivors with hemianopia or any visuospatial neglect were excluded from this study; thus, how these deficits affect the eye-hand coordination was not examined

• Knee proprioception assessment adopted in this study might not be specific to the postural stability task.

Conclusion• Training of eye-hand coordination in sitting and

standing are important– Due to the poor performance in reaction and movement time

in both sitting and standing position in paretic side

• Reaching training on AP direction may be useful for

the rehabilitation of eye-hand coordination.

– Due to the high demand of postural stability

• Strengthening the elbow flexors and grip may help the

eye-hand coordination

CONFLICT OF INTEREST

Authors disclose no conflict of interest

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Critical analysisStrength of the study

– One of the rare study which examines the

interrelationship between eye hand coordination and

postural stability – Findings of this study helps in

‘transfer of learning’ of skills to real life situations

– Previously tested procedure has been used for the

assessment of eye hand coordination, proprioception

etc…

Critical analysis‘Weakness’ of the study• Study Hypothesis is not clearly stated

• Justification for inclusion and exclusion criteria are not

mentioned / referenced

• Correlation of reaction time, movement time and accuracy with

functional reach test is not clearly depicted in the given table

• Potential confounding variables are not addressed. Like fear of

fall etc…

Critical analysis• Comments

– …in such a scenario, instead of paired ‘t’ test, Odds ratio

could have been used for the statistical analysis to find

out the association between the variables than just to

find out the mean difference between the variables

– Reaching task could have been more ‘functional’ where

the researchers can really examine a ‘contextually

relevant functional task’

Potential Implications• Training of eye-hand coordination in sitting and standing

posture can be further emphasized in our practice

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Questions ?

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Thank you..!