Frontoethmoidal encephalocele with subependymal nodular heterotopia: an unusual association. A case report.

Frontonasal encephaloceles involve herniation of meninges and brain tissue through defects in the floor of the anterior cranial fossa affecting the frontal, ethmoid and nasal bones. Subependymal nodular heterotopias are malformations of cortical development resulting from abnormal neuronal migration. This report describes the coexistence and association of these two entities which is extremely rare. We describe an unusual case of a six-year-old girl with a frontonasal encephalocele in whom further imaging disclosed subependymal nodular heterotopias. Clinically she presented with swelling over the glabella since birth but otherwise was asymptomatic. CT and MRI showed herniation of brain tissue with the overlying dura and CSF through a defect in the frontal, ethmoid and nasal bones. In addition, MRI revealed heterotopic nodules in the subependymal regions of the lateral ventricles that were isointense with grey matter on all sequences. The patient underwent one stage surgery for correction of the encephalocele.