Distribution of leptomeningeal glioneuronal heterotopia in alobar holoprosencephaly

M. Mizuguchi, S. Maekawa and S. Kamoshita
Department of Pediatrics, Faculty of Medicine, University of Tokyo, Japan.

OBJECTIVE: To clarify the pathogenetic significance of the topographic distribution of leptomeningeal glioneuronal heterotopia, a common finding in holoprosencephaly. DESIGN: Gross, histological, and immunohistochemical observations of alobar holoprosencephaly in brain specimens taken at autopsy. SETTING: Referral center. MATERIALS: Brains removed at autopsy from five consecutive patients with alobar holoprosencephaly. MAIN OUTCOME MEASURES: Immunoperoxidase staining for glial fibrillary acidic protein. RESULTS: In all brains, leptomeningeal glioneuronal heterotopia showed an identical distribution, ranging from the basal prosencephalon to the pons, with the thickest distribution occurring in the basal prosencephalon. CONCLUSION: The constant localization implicates leptomeningeal glioneuronal heterotopia in severe dysgenesis of midline prosencephalon, the basic pathogenesis of the anomaly.