Septo-optic dysplasia plus

Abstract

A 20-year-old man, with a history of congenital nistagmus and mild global developmental delay, presented with four left clonic seizures, which had each lasted for several minutes. A neuro-ophthalmic examination revealed a pendular nistagmus—attenuated with the gaze in the primary position—as well as hypoplasia in both optic discs and amblyopia. We could not observe the septum pellucidum on coronal MRI but saw right frontal subependymal nodular heterotopia (figure). We started treatment with valproic acid and the seizures did not recur. Septo-optic dysplasia (SOD) is a developmental malformation reported by De Morsier that includes dysgenesis of the septum pellucidum, optic nerve hypoplasia, and other cerebral malformations. It is thought of a disorder of midline prosencephalic development. The symptoms, which occur especially when a disorder of cortical development is also present (SOD plus), consist of visual defects, endocrinological manifestations, developmental delay, motor deficits, and epileptic seizures. 1 SOD plus is most frequently associated with schizencephalia, which is now recognised in the current classification of malformations of cortical development, 2 as a differentiated syndrome called schizencephalia septooptic dysplasia. SOD-plus is currently thought to be a genetic disorder that affects multiple stages of cortical development, as opposed to the classical vascular theory based on its association with schizencephalia. Two cases of SOD plus associated with polymicrogyria have recently been published.