Neuropediatrics 2006; 37 - THP116
DOI: 10.1055/s-2006-945939

CLINICAL DIFFERENCES IN TYPICAL AND ATYPICAL TYPES OF HEMIMEGALENCEPHALY

M Sasaki 1, K Sugai 1, Y Fujikawa 1, E Nakagawa 1, H Komaki 1, H Nakama 1, T Ohtsuki 1
  • 1National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan

Objectives: To investigate the diverse clinical severity of hemimegalencephaly, we compared the symptoms and neuroimaging findings in a cohort of patients with this disease.

Methods: Twelve patients were divided into two groups according to their MRI findings. Group 1 (6 patients) showed typical MRI of hemimegalencephaly, i.e. hemispheric broad gyri and shallow sulci, and advanced myelination or an increased volume of white matter. Group 2 patients showed atypical MRI findings, i.e. focal megalencephaly, a large amount of heterotopia, or a mild type of hemimegalencephaly.

Results: Five of the 6 patients in Group 1 presented with EIEE within 1 month of age, and underwent functional hemispherectomy. All 5 patients could not walk. One patient presented with focal motor seizures at 8 months of age, and has been able to walk and speak several words since 3 years of age. In Group 2, 3 patients showed focal megalencephaly, one patient showed a large amount of heterotopia and cortical dysplasia, and two patients had a mild type of hemimegalencephaly. One of the three patients with focal megalencephaly showed progressive atrophy in the lesion. Another patient displayed an increased volume of focal lobes after 1 year of age. All 3 patients with the focal type of hemimegalencephaly showed early epileptic seizures and severe psychomotor retardation. The patient showing a large amount of heterotopia and the patient with the mild type of hemimegalencephaly both presented with only mild clinical symptoms. These latter two patients could walk and speak since 3 years of age.

Conclusion: Patients with hemimegalencephaly present with diverse neuroimaging findings, which do not correlate clearly with the clinical severity of the condition.