Post-Exchange Transfusion Convulsions on Phenobarbitone: Follow-Up Plan

Context

Immediate Post-Seizure Stabilisation (Before Discharge Planning)

1. Correct the metabolic trigger first - most post-ET seizures are hypocalcaemia (citrate chelation from blood bank donor blood):
   • Check ionised Ca²⁺, glucose, Na⁺, Mg²⁺, K⁺ urgently
   • Give 10% calcium gluconate 2 mL/kg IV slowly if hypocalcaemia confirmed
   • Correct hypoglycaemia (GIR 6-8 mg/kg/min), hyponatraemia, hypomagnesaemia accordingly
2. EEG - continuous or prolonged EEG monitoring is the gold standard; clinical seizure detection in neonates is unreliable. EEG establishes whether seizures are controlled (electroclinical uncoupling is common after phenobarbitone - the baby looks seizure-free but electrical seizures persist)
3. Neuroimaging - cranial ultrasound bedside immediately; MRI brain when stable. Look for: kernicterus pattern (basal ganglia T1 bright, T2 changes), intracranial haemorrhage, HIE changes
4. Sepsis screen - LP, blood culture, empirical antibiotics/antivirals if not already done
5. Phenobarbitone maintenance - 3-5 mg/kg/day in once or twice daily doses; therapeutic levels 20-40 mcg/mL

Follow-Up Plan

In the NICU (Before Discharge)

Decision: Continue or Stop Phenobarbitone at Discharge?

• Early discontinuation before discharge (vs. continuing for months) showed no difference in neurodevelopment or epilepsy risk at 24 months
• These results support stopping ASM before hospital discharge for most infants with acute symptomatic seizures

• Metabolic cause identified and fully corrected (e.g., pure hypocalcaemia post-ET)
• Seizures resolved within 48-72 h, no recurrence
• Normal or near-normal EEG background at discharge
• Normal neurological exam
• No underlying structural brain injury

• Status epilepticus in the neonatal period
• Severe HIE or kernicterus (basal ganglia injury on MRI)
• Required multiple AEDs to control seizures
• Persistently abnormal EEG background (burst suppression, low voltage)
• Ongoing metabolic or structural risk

Outpatient Follow-Up Schedule

• Review neurological exam - tone, suck, Moro, grasp, alertness
• Phenobarbitone level if continued (check trough; adjust if sub-therapeutic or toxic)
• Recheck bilirubin if concern for rebound
• Screen for feeding difficulties, weight gain

• Repeat EEG - background maturation, presence of interictal discharges
• Consider discontinuing phenobarbitone at this visit if seizure-free and EEG normal (especially if the only cause was transient metabolic disturbance)
• Development surveillance: social smile, visual tracking, head control
• Cranial MRI at ~3 months if not yet done (basal ganglia signal for kernicterus, HIE sequelae)

• Formal developmental assessment (Bayley Scales or equivalent)
• EEG - watch for infantile spasms (hypsarrhythmia) - 10-30% of neonatal seizure survivors develop epilepsy; infantile spasms over-represented in this group
• Neurology review with MRI if not yet done

• Formal hearing assessment (BERA/ABR) - kernicterus causes sensorineural hearing loss (high-frequency, auditory neuropathy pattern)
• Ophthalmology review - oculomotor abnormalities in kernicterus
• Physiotherapy referral if hypo- or hypertonia

• Annual developmental/neurological review until school age
• GMDS/Griffiths/Bayley at 12, 24 months
• Neurodevelopmental impairment occurs in 25-70% of survivors; early intervention (PT, OT, speech) improves outcome
• Epilepsy risk: 10-30% develop postneonatal epilepsy; higher with structural injury

Hearing Loss - Specific to Bilirubin Encephalopathy

• Look for absent or delayed wave V, elevated thresholds
• Auditory neuropathy spectrum disorder (ANSD) is the characteristic pattern
• Early hearing aid fitting and speech therapy markedly improve language outcomes

Phenobarbitone Weaning Protocol (if decision to wean at 3 months)

• Reduce dose by 25% every 2-4 weeks
• Monitor for seizure recurrence during wean
• No need for serum levels during wean if clinical monitoring adequate
• Do not abruptly stop - taper over 4-6 weeks minimum

Key Safety Points

• Phenobarbitone neuroapoptosis concern: Animal data (rat models) show even a single dose causes neuronal apoptosis and memory/learning deficits. This is a major driver for minimising duration - do not continue longer than clinically necessary.
• Drug interactions: Phenobarbitone induces CYP enzymes; check for interactions with any concurrent medications.
• Vitamin D and Ca²⁺: Phenobarbitone induces hepatic metabolism of Vitamin D - supplement Vitamin D (400-800 IU/day) if continuing beyond 1 month.

Summary of Follow-Up Framework

Discharge → Wk 2-4: Neuro exam, PB levels, bilirubin check
         → 1-3 mo: EEG, consider stopping PB, development screen
         → 3-6 mo: MRI brain, ABR hearing test, Bayley assessment
         → 6-12 mo: Epilepsy surveillance, OPD neuro, ophthalmology
         → 12-24 mo: Formal developmental assessment, PT/OT/speech referral

• Bradley and Daroff's Neurology in Clinical Practice (Neonatal Seizures - Management, Prognosis sections)
• Rosen's Emergency Medicine (Neonatal Seizures)
• Glass HC et al., "Safety of Early Discontinuation of Antiseizure Medication After Acute Symptomatic Neonatal Seizures," JAMA Neurol 2021 [PMID 34028496]