Hypoxic-ischaemic encephalopathy

Question 1

HIE - overview

Answer 1

1. When labour does not go well, the fetal brain may be damaged by hypoxia (reduced oxygen supply) or ischaemia (reduced blood supply) -> hypoxic-ischaemic encephalopathy (HIE)
2. Affects 1-4 per 1000 births
3. Severe asphyxia may cause acute encephalopathy in a previously normal brain (whole fetus will also be affected, not just the brain)
4. Damage caused to brain by HIE and consequent neuronal cell death occurs in two phases - first phase = primary cell death, followed by secondary or delayed cell death between 8 and 72 hours of age -> can result in major neurological and developmental deficits in the infant
5. HIE graded from mild to severe. Dx of HIE requires knowledge that there has been true hypoxia or acidaemia

Question 2

HIE - mild (3)

Answer 2

1. Increased muscle tone, brisk reflexes
2. Transiently abnormal behaviour (e.g. poor feeding, irritability or excessive crying)
3. Normal by 3-4d

Question 3

HIE - moderate (3)

Answer 3

1. Lethargy and hypotonia, diminished reflexes
2. Possible apnoeic periods and seizures in the first 24 hours of life
3. Full recovery in 1-2 weeks may occur and is associated with better long-term outcome

Question 4

HIE - severe (5)

Answer 4

1. Stupor or coma
2. Irregular breathing, hypotonia, absent neonatal reflexes
3. Disturbed ocular motion, pupils may be dilated, fixed or poorly reactive
4. Early seizures that may not respond well to conventional treatment
5. Multi-organ dysfunction may occur (cardiac, respiratory, renal, hepatic, haematological, neurological)