Abstracts

Rationale: Provide improved characterization of the evolution of Hemimegalencephaly (HME) in adult patients. HME is a rare neurological migration disorder resulting in the enlargement of one hemisphere. Depending on the severity of the enlargement, clinical manifestations may include macrocephaly, colpocephaly, epilepsy, and impaired psychomotor development. HME may also be associated with various neurocutaneous syndromes. One neurocutaneous syndrome is Hypomelanosis of Ito (HI). The main characteristics of HI are hypopigmented skin areas along the lines of Blaschko, which appear as streaks and patches. Methods: Retrospective chart review on patients diagnosed with HME examining seizure frequency, family history, treatment, associated conditions, cognitive evolution, neuroimages, and EEG findings. Out of 1600 patients seen in our Epilepsy Clinic, four were diagnosed with HME. Results: Diagnosis of HME was determined after the onset of early childhood or infantile epilepsy. Neuroimaging involving CT, MRI, and angiogram confirmed an enlarged hemisphere with dilated ventricles. Imaging findings revealed: loss of grey-white matter differentiation, heterotopias, and ventricular enlargement. Treatment with anti-epileptic medications did not provide complete seizure control. Two of the patients with seizure frequencies exceeding 15 seizures/day underwent hemispherectomy at ages 2 and 9 years. While these patients continue to experience daily seizures, seizure control significantly improved. Of the four patients, three presented hypomelanotic patches on their neck, trunk, arms, and legs. All patients exhibit some form of psychomotor developmental delay and varying degrees of mental retardation or learning disabilities.Conclusions: We present four adult patients previously diagnosed with HME; three showing signs of HI in association with HME. While there have been numerous case studies and literature reviews on HI and HME, in association with each other or not, all current studies involve children or infants with few detailing adult cases. We reviewed the literature to discuss the adult evolution of HME.