hemimegalencephaly

Full Definition

A rare congenital brain malformation characterized by hamartomatous overgrowth of one cerebral hemisphere or part of a hemisphere, often associated with cortical dysplasia, enlarged neurons, and balloon cells. The condition typically presents with medically refractory seizures beginning in infancy, developmental delays, and progressive hemiparesis. Hemimegalencephaly may occur in isolation or as part of genetic syndromes such as CLOVES syndrome or Proteus syndrome. Surgical intervention, including hemispherectomy, may be necessary for seizure control.

In Context

• "The patient underwent functional hemispherectomy for treatment of refractory seizures secondary to hemimegalencephaly." — Neurosurgical operative report
• "Prenatal ultrasound suggested possible hemimegalencephaly with asymmetric ventricular enlargement." — Fetal medicine consultation