Background: Hemimegalencephaly (HME) is a rare, congenital brain malformation associated with drug-resistant seizures that are challenging to manage in young infants. Hemispheric surgery in infants <3 months of age carries increased risks of blood loss and complications due to the fragility of the immature brain parenchyma and cerebral vasculature. Transarterial embolization (TAE) has emerged from an adjunct to surgery to a potential alternative to hemispherectomy in a subset of HME patients.

Objective: To review the safety, efficacy, and evolution of TAE performed in infants <3 months of age with medically refractory seizures due to HME.

Methods: We retrospectively reviewed patient demographics, intraprocedural events, procedure-related complications, and epilepsy characteristics for all infants who underwent TAE between 2013 and 2024 at a single quaternary institution.

Results: Thirteen patients underwent a total of 41 embolizations, with a mean age of 45.5±26.8 (range 10-99) days at first embolization. Procedure-related complications included femoral arterial occlusion (n=2), symptomatic intracranial hemorrhage resulting in progressive hydrocephalus requiring cerebrospinal fluid shunting (n=1), and non-target embolization (n=2). One mortality occurred from multifocal intraparenchymal hemorrhages due to post-procedure coagulopathy. Two patients developed delayed contralateral ischemic injury. Engel Class I (free of disabling seizures) was achieved in 72.7% (8/11) of patients, with a mean follow-up age of 4.4±3.6 (range 1.3-11.0) years.

Conclusions: TAE is a potential alternative to hemispherectomy for refractory epilepsy due to HME in infants <3 months of age; however, technical and perioperative challenges remain important considerations. Optimizing patient selection and periprocedure care are critical factors to improve patient outcomes.