Abstracts

RATIONALE: Temporal negative sharp waves can be a normal feature of preterm neonatal EEGs. They tend to appear more frequently in newborns with seizures and are considered signs of "cortical irritability" but their meaning and long term significance is often unclear. METHODS: We evaluated prospectively serial EEGs done in preterm and term neonates with suspected seizure activity and graded the appearance of sharp waves by a simple classification system: grade 0- normal, I- occasional sharp waves, greater than expected for age, II- marked excess of sharp waves with (A) diffuse or (B) focal localiza- tion, III- significant multifocal sharp waves (MFSW) with polyphasic activity and IV- electrographic seizures. A score was also assigned to the background activity from 0-3. All infants had cranial ultrasounds and were followed up till one year of age to assess neurologic and developmental status and the presence of epilepsy. Infants whose final NICU EEG was abnormal were discharged home on phenobarbital. Follow-up EEGs were done at 2-3 months and 6-7 months, corrected age. RESULTS: Over 30 infants were included in this study. We had five term newborns and the average gestational age of the preterm group was 27.4 weeks. EEGs with a MFSW grade II or higher remained abnormal in repeat studies done during the NICU admission. These infants, whose cranial ultrasounds were generally normal, required phenobarbital since low therapeutic levels of this medication was associated with breakthrough seizures. Once home, follow-up EEG recordings were often normal and phenobarbital was discontinued successfully. Periventricular leukoma- lacia (PVL) was associated with MFSW in the absence of clinical seizure activity, but infants with intraventricular hemorrhages (IVH) and seizures often required anticonvulsant treatment beyond the first few months of life. CONCLUSIONS: In the absence of structural lesions, Grade II or higher MFSW indicated increased risk for seizures in the newborn period but did not predict epilepsy in the first year of life. Infants with MFSW and IVH needed prolonged antiseizure medication but those with MFSW and PVL did not.