Clinical and radiological evaluation of children with hemimegalencephaly and epilepsy: A single-center study

Hemimegalencephaly (HME) is characterized by severe seizures, cognitive impairment, and unilateral motor deficits. This study aimed to evaluate the clinical features, electroencephalogram (EEG) and neuroimaging findings along with treatment outcomes in pediatric epilepsy patients diagnosed with HME.

A retrospective review was conducted on 14 pediatric epilepsy patients with HME, encompassing clinical data, video-EEG findings, neuroradiological assessments and treatment outcome.

The study revealed a predominance of left-sided HME (11/14) and syndromic presentations in three patients. The median age of seizure onset was within the first day of life (range: 0-225 days). The median follow-up duration was 30 months (3-72 months). All patients experienced daily seizures. At the time of evaluation, 11 patients were on three or more antiseizure medications. Adjunctive therapies included ketogenic diet in four patients, mTOR inhibitors in two patients, and a combination of both in one patient. Ictal recordings were obtained in 13 patients, with two patients exhibiting bilateral independent ictal onset. All but one patient demonstrated refractory seizures on follow-up. Six patients (42.8 %) underwent epilepsy surgery, resulting in seizure freedom in three cases (50 %) and a mild reduction in seizure frequency in one. Two patients experienced intraoperative hemorrhage, resulting in monthly seizures and postoperative mortality, each in one patient.

Hemimegalencephaly represents a challenging etiology in refractory epilepsy of early childhood. Given the limited efficacy of pharmacological modalities, epilepsy surgery seems to be the only effective treatment option for seizure control in these young patients, however, carries significant risks for mortality and morbidity.