Distribution of leptomeningeal glioneuronal heterotopia in alobar holoprosencephaly.

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.