Can birth asphyxia result in learning difficulties without cerebral palsy?

1
Can birth asphyxia result in learning
difficulties without cerebral palsy?

• Ben Lloyd
• Consultant Paediatrician
• Royal Free Hospital, London
• AvMA 19th September 2007

2
Seamus

3
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

4
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)

5
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

6
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

7
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

8
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

9
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

10
One lesson from Christines case

• Clinical features can be misleading.
• MR scan often crucial in establishing
  causation

11
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

12
Annie - part 2

• MR scan showed extensive watershed damage
• Annies learning difficulties can be confidently
  attributed to birth asphyxia

13
One lesson from Annies case

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

14
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

15
Professor Charlene Robertsons 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

16
Summary of Prof Robertsons 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

17
What Professor Robertsons work contributes

• Learning difficulties (without cerebral palsy)
  are common after birth asphyxia and
  encephalopathy - about 10
• BUT no evidence to challenge Lewis Rosenblooms
  assertion that in such cases there must be an
  abnormal MR scan in order to establish causation

18
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

19
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

20
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

21
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

22
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

23
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

24
Diffusion Tensor ImagingNagy and coworkers

• 8 survivors of moderate HIE without CP
• 3 had IQlt70 3 had IQ gt70 but lt85
• 4 had normal conventional MR scan
• DTI (specific for white matter damage) showed
  abnormalities in all 8 - controls had fewer
  abnormalities

25
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

26
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 2000123 499-507

27
My own experience - part 1

• I have reviewed 350 cases in which birth
  asphyxia has been queried as a cause of a childs
  impairments
• In just over 100 of these cases were the
  impairments caused by asphyxia

28
My own experience - part 2

• 12 children with learning difficulties and no
  cerebral palsy following birth asphyxia
  encephalopathy
• All had negative family histories

29
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

30
How many normal MR scans would you expect if
Lewis Rosenbloom is right?

• Robertson reported that 9.8 of survivors had an
  IQlt70 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 9.82.3 -
  ie 4.31

31
My own experience

• If Lewis Rosenbloom is right (and Prof
  Robertsons numbers are right) one would expect
  ratio of abnormal to normal MR scans of children
  with learning difficulties after birth asphyxia
  to be 4.31 - 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 26 - ie most had a normal scan

32
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 2000123 499-507

33
Diffusion Tensor ImagingNagy and coworkers

• 9 survivors of moderate HIE without CP
• 3 had IQlt70 3 had IQ gt70 but lt85
• 4 had normal conventional MR scan
• DTI (specific for white matter damage) showed
  abnormalities in all 9 - controls had fewer
  abnormalities

34
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

35
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

36
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.

37
Seamus part 3

• Quantitative study of hippocampus undertaken by
  Professor Gadians team
• Significant hippocampal atrophy found
• Seamuss impairments likely to be caused by
  substandard obstetric care

38
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

39
Questions?

40
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

41
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.