Don't call it birth asphyxia! That might imply management at birth was suboptimal, whereas you don't usually know at what point the baby started getting into trouble. Obstetricians won't thank you either for pointing the finger at them. Mechanism - hypoperfusion leading to glutamate excess, ATP depletion, uncontrolled Calcium influx, free radicals. Blood pressure goes up first to compensate, but autoregulation is probably impaired and reperfusion injury occurs. Finally, apoptosis is induced, ie neuronal death continues for some weeks after the initial insult.
Markers of fetal distress eg CTG, scalp/cord pH (esp BE -12 or worse), APGARs, meconium are not very good at predicting HIE; specificity is very poor. A hydrogen ion below 100 is poorly prognostic, as is a 10 minute APGAR under 5. Remember to consider underlying illness too eg a metabolic condition, predisposing to difficulty in labour.
Sarnat and Sarnat classify HIE into mild/moderate/severe.
Beware an initial period of mild HIE then being followed by sudden deterioration, indicative of reperfusion injury.
Other systems are often involved:
Investigations:
Management is essentially supportive, aiming to avoid secondary brain injury - cerebral perfusion is crucial, so BP should be optimized and CO2 normalized. Anticonvulsants do not have any role prophylactically but should be used to suppress seizures (on EEG or clinical). Fluid, electrolyte and glucose control (anticipating renal failure and SIADH). Introduce feeds gradually.
Prognosis: the sooner EEG patterns normalize the better; a persistent abnormal EEG is predictive of severe deficits or death, with a cut off at 48hrs. Burst suppression in the first 6 hrs gives a likelihood ratio of 2.7 for adverse outcome, but this rises to 19 between 24-36 hrs. Nonetheless, a number of bad EEGs (burst suppression or low voltage) will develop normally! Pediatr Res Jun 2004 PMID: 15155870. Sarnat grade 1 do uniformly well, whereas grade 3 have 80% long term disability. This is mostly cerebral palsy but increasinlyg cognitive defects are being discovered in the absence of a motor problem. Grade 2 has a much more variable outcome: on average, IQ is lower but still within normal range; there is some evidence that there are more behavioural problems eg autism, hyperactivityEur J Peds, PMID 17426984. Neurological examination is still very important, especially when done serially: abnormalities of tone or suck beyond day 7 are poor prognostic indicators. Poor head growth in the first year predicts neurodisability.
Can be done by head cooling or whole body cooling, to about 33.5 degC. Cochrane finds in favour: reduced mortality/major neurodevelopmental disability at 18 months of age (typical RR 0.76) which gives NNT of 8-11. But many studies still ongoing (given the long follow up). Many complications are described but incidence seems very low. Head (CoolCap) - Lancet 2005 Feb 19-25;365(9460):663-70. Whole body - Pediatrics 2008, PMID 18829776; TOBY BMC Pediatrics, PMID 18447921 .
Resuscitation with room air is more physiological, and less likely to lead to free radical damage, at least in theory. Not much evidence yet, but no evidence of harm either.
Metabolic
Non-ketotic hyperglycinaemia: presents in first few days with hiccoughs, apnoea, intractable seizures, spasticity, coma
Cerebrovasc
Others
Underdiagnosed, sleep myoclonus can mimic status, except that waking the baby terminates the movements. ? FH of myoclonic jerks. Anticonvulsants make WORSE by making the baby more drowsy. Usually settles with maturation of sleep pattern at about 3 months, but may last up to 3 years.
Abnormal radial gyri pattern on sagittal view, bat wing +/- expanded tips on coronal (cingulate sags down, stretches ventricle into U shape. Colpocephaly (ie disproportionate expansion of post horn) associated.
Spina bifida babies often have leg movements in the first week of life that then disappear, probably would happen even with fetal surgery. (Pediatrics 2004)
Sundrum et al suggest 51% of CP attributable to inequality, because v low rate in SEC 1 - but not a consistent finding, no clear trend down classes, and high rates of CP in unclassified. Arch Dis Child 2005;90:15�18. (Ed by Pharaoh).
Misnomer of course, should be intracranial haemorrhage.
Early [1st 24 hrs] is probably a different entity from late - different risk factors apply. Inflammatory markers do not predict independently, but seem relevant in context of vaginal delivery with no or incomplete antenatal steroid course (increased risk of early but not late IVH) PMID 16549908
Grades 1-2 have a normal prognosis (ie same as a premature newborn without haemorrhage, so still at risk of neurodevelopmental disability due to infection, etc). Grade 3 is tricky, a proportion will still have a normal outcome, but a proportion will do badly. Grade 4 has a very poor prognosis.
DRIFT study - drainage (frontal & occipital catheters), irrigation & fibrinolysis for IVH vs LPs/reservoir to reduce shunt dependence & disability (Bristol).
IVH does occur in term babies - from choroid plexus, especially post sinus thrombosis (of whatever cause).
Focal white matter damage, as characterized by echolucent/hypoechoic lesion, and diffuse damage, as suggested by late ventriculomegaly, are associated with delayed mental and psychomotor development. Ex preterms (<28/40 followed up at 2yrs) without cranial ultrasound abnormality had the lowest probability (23% and 26%) of delayed mental or psychomotor development. Moderate/severe ventriculomegaly was associated with a more than fourfold increase in the risk of psychomotor delay and an almost threefold increase in the risk of mental delay. PMID: 18762501
OT do activities of daily living, which for babies means play! Particularly good for developmental coordination disorder, autism, other sensory difficulties.
Basic principles are minimal handling, control of environmental noise/light.
Positioning should encourage Hand to mouth for self comforting. Boundaries, including swaddling, are there to provide comfort NOT to restrict movement (which may lead to shortening).
Most myelomeningocoeles will be picked up on antenatal scans, and the baby delivered electively in a neonatal surgical centre with a view to immediate closure.
Occult spinal dysraphism, where there is intact skin, occurs with unknown frequency, but is associated with spinal tethering, where the cord fails to ascend to its normal position (conus at T12 to L2) due to a persistent filum. Traction leads to ischaemia, causing neurological, musculoskeletal and urological abnormalities.
There are often other cutaneous clues, typically in the midline over the lumbar spine:
Dimples are common, and if blind ended of no significance. Otherwise, any such finding should be investigated further, either by US or MRI, with a view to preventing complications. Late diagnosis of spinal tethering is common, and it may not be possible to reverse complications, viz:
This work
is licensed under a Creative
Commons Attribution-Noncommercial-Share Alike 2.5 UK: Scotland License.