periventricular nodular heterotopia
Also written as: PNH — periventricular nodular heterotopia
A neuronal migration disorder characterized by clusters of ectopic neurons lining the lateral ventricles due to failed radial migration during development.
Full Definition
Periventricular nodular heterotopia represents a malformation of cortical development where neurons fail to complete their migration from the ventricular zone to the cortical plate during embryogenesis. The condition results in nodular collections of mature but ectopically located neurons that remain adjacent to the lateral ventricles, appearing as bilateral symmetric nodules on neuroimaging. Histologically, these nodules consist of well-differentiated neurons and glial cells organized in a disorganized fashion, lacking the normal cortical laminar architecture. The overlying cortex may appear normal or show subtle disorganization. This condition is frequently associated with epilepsy and may be caused by mutations in genes such as FLNA, ARFGEF2, or FAT4. Neuropathological examination reveals the characteristic nodular architecture with normal neuronal cytology but aberrant spatial organization.
Usage
Usage note: Often abbreviated as PNH in clinical contexts; ensure clear distinction from other periventricular abnormalities in reports.
In Context
- "Microscopic examination confirmed periventricular nodular heterotopia with well-formed but ectopically positioned neurons adjacent to the ventricular surface." — Surgical pathology report
- "The resected tissue showed typical features of periventricular nodular heterotopia with loss of normal cortical organization and nodular neuronal clustering." — Epilepsy surgery specimen