Can birth asphyxia result in learning difficulties without

cerebral palsy?

Ben Lloyd

Consultant Paediatrician

Royal Free Hospital, London

AvMA 19th September 2007

Seamus

Timetable

• Definitions of birth asphyxia + cerebral palsy

• Criteria to be met to link birth asphyxia + cerebral

palsy

• Current consensus about impairments after birth

asphyxia

• Evidence to challenge this consensus

• Summary of my view of the current situation

What is birth asphyxia

• Impaired placental gas exchange causing hypoxia (low oxygen level), high carbon dioxide levels and acidosis

• Hypoxia and acidosis cause impaired cardiac function which causes impaired brain circulation (ischaemia)

What is cerebral palsy

A motor impairment due to a non progressive lesion in the developing brain

Not necessary to have any learning difficulties - but usually have some

Necessary criteria to link cerebral palsy to birth asphyxia

• No antenatal cause• No postnatal cause• Evidence of fetal distress• Poor condition at birth• Metabolic acidosis at birth• Encephalopathy in first hrs/days of life• Four limb cerebral palsy• Characteristic MR changes

John

• Severe dyskinetic cerebral palsy• No antenatal or postnatal damage• Terminal bradycardia because of abruption• Severe encephalopathy• By 12 months diagnosed as dyskinetic

cerebral palsy• MR scan - characteristic changes following

acute, near total hypoxic-ischaemic insult

Christine

• No antenatal or postnatal damage

• Some fetal distress due to prostin - disputed how much fetal distress

• Apgars 7 & 9 - no active resuscitation

• Moderate and prolonged encephalopathy

• Cerebral palsy - considered to be hemiplegia

Christine - part 2

• Asymmetrical quadriplegia (4 limbs involved) - not hemiplegia (arm + leg on same side)

• MR - showed asymmetric watershed damage

• Good condition at birth due to autoresuscitation

One lesson from Christine’s case

Clinical features can be misleading.

MR scan often crucial in establishing causation

Annie

• Water birth - significant fetal distress

• Poor condition at birth. Acidosis

• Significant encephalopathy

• Normal development at 10 months

• Two and a half years old - delayed speech but normal motor development

Annie - part 2

• MR scan showed extensive watershed damage

• Annie’s learning difficulties can be confidently attributed to birth asphyxia

One lesson from Annie’s case

The MR scan can show asphyxial damage in children who have no cerebral palsy

Current consensus in relation to learning difficulties and asphyxia

“It is feasible to apply an asphyxial cause to this small group of children only if the relevant perinatal criteria are met and if there is evidence of hypoxic-ischaemic damage to the brain on imaging”

Lewis Rosenbloom - Clinical Risk 1996

Professor Charlene Robertson’s work

• Has written papers from the 1980s onwards showing that learning difficulties are common after birth asphyxia

• Papers not very clear about how many of these children did not have cerebral palsy and about how many had undergone CT or MR scanning

Summary of Prof Robertson’s findings

• Studied 407 children with moderate HIE who did not have cerebral palsy

• 40 of the 407 (10%) had DQ/IQ of less than 70 - significant cognitive impairment - versus 2.3% background rate

• Very little scanning evidence

What Professor Robertson’s work contributes

• Learning difficulties (without cerebral palsy) are common after birth asphyxia and encephalopathy - about 10%

• BUT no evidence to challenge Lewis Rosenbloom’s assertion that in such cases there must be an abnormal MR scan in order to establish causation

What is needed to overturn current consensus

• Large follow up study of survivors of asphyxia and encephalopathy

• Needs to be to at least school age

• Needs to include MR scans

A paper from Hammersmith Hospital

• 68 asphyxiated babies. 15 died. 19 had cerebral palsy. 34 others - studied, at age around 5-6.

• 3 children with IQ under 80.

• 1 child (IQ 76) had normal MR scan

Conclusions from Hammersmith Hospital paper

• Small study - just 34 children

• Children young - school performance may worsen

• Evidence could be used to either support or challenge the current consensus

Two papers from Sweden

• Starting cohort - all 684 Swedish babies with apgar of less than seven in 1985

• 56 of these developed encephalopathy; 43 agreed to be studied.

• 15 had cerebral palsy; so 28 in study

Swedish study - part 2

• All 28 interviewed on phone; 11 had IQ testing; 8 had MR scans

• 5/28 had IQ less than 70

• In all, 11/28 had mild learning disability or borderline intelligence vs 2/15 sibling controls

MR findings in Swedish study

• Eight underwent MR scans - not clear who did and who did not undergo MR

• Three had periventricular leucomalacia

• One had watershed damage

Diffusion Tensor ImagingNagy and coworkers

• 8 survivors of moderate HIE without CP

• 3 had IQ<70; 3 had IQ >70 but <85

• 4 had normal conventional MR scan

• DTI (specific for white matter damage) showed abnormalities in all 8 - controls had fewer abnormalities

Conclusions from Swedish studies

• Learning difficulties with no cerebral palsy are common after birth asphyxia

• At least some children with learning difficulties probably had normal conventional MR scans

• Many/most/all children with normal conventional MR scans had abnormal findings on diffusion tensor imaging

Quantitative MR studiesGadian and coworkers

• Five babies suffered severe hypoxia-ischaemia

• All now have severe memory problems• No cerebral palsy• Conventional MR normal• Quantitative MR studies showed severe

hippocampal atrophy in all cases

• Brain 2000:123; 499-507

My own experience - part 1

• I have reviewed 350+ cases in which birth asphyxia has been queried as a cause of a child’s impairments

• In just over 100 of these cases were the impairments caused by asphyxia

My own experience - part 2

• 12 children with learning difficulties and no cerebral palsy following birth asphyxia+ encephalopathy

• All had negative family histories

My own experience part 3

Of the 12 children with learning difficulties and no cerebral palsy:

• 2 had obvious asphyxial damage on MR

• 6 had normal MR scans

• 4 have not undergone an MR scan

How many normal MR scans would you

expect if Lewis Rosenbloom is right? • Robertson reported that 9.8 % of survivors had

an IQ<70 vs 2.3% expected in general population

• Thus, would expect some to have normal MR scans - because the asphyxia was coincidental

• If Lewis Rosenbloom is right then would expect ratio of abnormal to normal scans to be 9.8:2.3 - ie 4.3:1

My own experience

• If Lewis Rosenbloom is right (and Prof Robertson’s numbers are right) one would expect ratio of abnormal to normal MR scans of children with learning difficulties after birth asphyxia to be 4.3:1 - ie most would have abnormal scans

• In my very small series (but larger than any published series

of children with LDs after asphyxia/encephalopathy) of eight children the ratio is 2:6 - ie most had a normal scan

Quantitative MR studiesGadian and coworkers

• Five babies suffered severe hypoxia-ischaemia

• All now have severe memory problems• No cerebral palsy• Conventional MR probably normal• Quantitative MR studies showed severe

hippocampal atrophy in all cases

• Brain 2000:123; 499-507

Diffusion Tensor ImagingNagy and coworkers

• 9 survivors of moderate HIE without CP

• 3 had IQ<70; 3 had IQ >70 but <85

• 4 had normal conventional MR scan

• DTI (specific for white matter damage) showed abnormalities in all 9 - controls had fewer abnormalities

Role for specialised MR

Diffusion Tensor Imaging - not yet available. Needs more research before could cite in Court.

Quantitative examination of the hippocampus - is available in UK. Consider for children with memory problems

Seamus

• Severe acute near total asphyxia due to shoulder dystocia

• No heart beat for seven minutes• Very severe encephalopathy• “Normal” at 18 months - according to

professor of developmental paediatrics• Age six - learning difficulties and

clumsiness

Seamus - part 2

• Age 17 significant learning difficulties - particularly memory.

• Normal size head

• No motor deficit

• Intelligent parents

• Normal MR scan. I advised further study.

Seamus part 3

• Quantitative study of hippocampus undertaken by Professor Gadian’s team

• Significant hippocampal atrophy found

• Seamus’s impairments likely to be caused by substandard obstetric care

The next few years

• More studies of survivors of asphyxia + encephalopathy with MR results will be published

• DTI and other newer MR techniques will become available

• I consider consensus will shift

Questions?

Summary - 1

• Most babies whose brain is damaged by birth asphyxia will have frank cerebral palsy and an abnormal MR scan

• Some babies whose brain was damaged by birth asphyxia will have learning difficulties but no cerebral palsy. Some/many will have an abnormal conventional MR scan

Summary - 2

• If clinical features (perinatal + family history) are supportive, then a child with learning difficulties but no cerebral palsy should undergo a conventional MR scan

• If conventional MR scan normal and poor memory consider quantitative study of hippocampi via Professor Gadian

• Consensus likely to change in next few years Just wait.