Neurologic System
HIE and therapeutic hypothermia
Hypoxic-ischemic encephalopathy is staged by Sarnat criteria (alertness, tone, reflexes, seizures). Cooling criteria generally include gestation of 36 weeks or more, birth weight at least 1800-2000 g, evidence of acidosis (cord pH 7.0 or less or base deficit 16 or more), 10-minute Apgar 5 or less, or resuscitation at 10 minutes, plus moderate-to-severe encephalopathy. Start within 6 hours, target 33.5 degrees C for 72 hours, then rewarm slowly. Avoid hyperthermia during transport.
Seizures and monitoring
Neonatal seizures may be subtle: eye deviation, cycling, apnea, or autonomic changes. Amplitude-integrated EEG is useful; conventional EEG is definitive. Phenobarbital 20 mg/kg load is first-line; refractory seizures may need 40 mg/kg total loading, then levetiracetam or midazolam.
IVH and PVL
Germinal matrix hemorrhage occurs in preterm infants; grade I-II is common, grade III-IV carries hydrocephalus risk. Prevention includes antenatal steroids, delayed cord clamping, midline head position, minimal handling, and avoiding rapid volume or blood-pressure swings. PVL is white-matter injury linked to hypoxia, infection, and hemodynamic instability.
Worked example
A term infant after uterine rupture has cord pH 6.85, base deficit 20, lethargy, and hypotonia at 2 hours. Reasoning: meets cooling criteria if 36 weeks or more with no contraindication; begin cooling within 6 hours and arrange MRI at 4-7 days. Do not wait for seizures.
Traps
- Confusing jitteriness with seizures; jitteriness is stimulus-sensitive and stops with holding.
- Cooling an outborn infant after 6 hours without specialist discussion.
- Missing hypoglycemia, hypocalcemia, or sepsis as seizure causes.