Hemispheric epilepsy surgery for hemimegalencephaly: The UCLA experience

Area of Science:

• Neurology
• Neurosurgery
• Pediatric Epilepsy

Background:

• Hemimegalencephaly (HME) is a rare congenital brain malformation.
• It predominantly presents with drug-resistant epilepsy in children.
• Hemispheric disconnective surgery is the primary treatment, but outcomes across techniques are not well-defined.

Purpose of the Study:

• To compare postoperative outcomes across different surgical techniques for HME.
• To identify clinical and intraoperative variables predicting seizure freedom in HME patients.

Main Methods:

• Observational study of 56 HME patients at UCLA (1984-2021).
• Patients stratified by surgical intervention: anatomic hemispherectomy (AH), functional hemispherectomy (FH), or less-than-hemispheric resection (LTH).
• Comparison of seizure freedom, functional outcomes, and complications; regression analysis for predictive variables.

Main Results:

• 49% of patients achieved seizure freedom at median 55-month follow-up.
• Anatomic hemispherectomy (AH) trended towards better seizure freedom than functional hemispherectomy (FH) (75% vs. 46%).
• Younger age at seizure onset, absence of epilepsia partialis continua (EPC), and no contralateral EEG seizures independently predicted longer seizure freedom.

Conclusions:

• Earlier age at seizure onset, absence of EPC, and no contralateral EEG seizures are associated with longer postoperative seizure freedom in HME.
• Anatomic hemispherectomy (AH) may offer improved seizure freedom with comparable outcomes to functional hemispherectomy (FH) for HME.
• Findings inform clinical decision-making for HME surgical management.