Seizure Burden and Management in Infants With Hemimegalencephaly Prestaged and Poststaged Transarterial Embolization

Hemimegalencephaly is characterized by unihemispheric hypertrophy, early-onset intractable epilepsy, and developmental delay. Staged transarterial embolization (TAE) was developed to reduce seizure burden in infants. This study characterizes the seizure profiles and management of infants treated with TAE.

Retrospective review of infants <3 months at Children's National Hospital from 2018 to 2023, including demographics, seizure profile, and medication management.

Eight infants underwent TAE. The mean age of seizure onset was 9 (0-28) days old, and the average age of first embolization was 50 (13-99) days old. Four patients underwent three stages, three patients had four stages, and one patient had five stages. In the first week of seizure onset, 6 (75%) patients had focal impaired consciousness seizures with elementary motor phenomena and 3 (50%) developed epileptic spasms later. Additionally, 2 (25%) had focal impaired consciousness seizures with autonomic or cognitive phenomena. In the 24 hours before the first embolization, 6 (75%) patients had frequent recurrent electrographic seizures and one (17%) had frequent recurrent electroclinical seizures. At discharge, electrographic seizure freedom was achieved in 6 (75%) of patients, and rare electrographic-only seizures in 2 (25%) patients. One (13%) patient was seizure-free on the megalencephalic hemisphere but developed seizures on the contralateral hemisphere. Patients had a median of 8 antiseizure medications during admission but weaned to a median of 4 medications at discharge.

All patients achieved complete resolution of electroclinical seizures from the affected hemisphere. Infants require escalation of antiseizure medications transiently, but after the final TAE, decreased to more typical epilepsy polytherapy.