Septo-optic dysplasia and bilateral schizencephaly

MRI of a patient, age 37 years, with a long history of epilepsy, blindness, and hemiparesis. Sagittal T1-weighted (A) MRI shows an abnormal course of fornix (arrow) caused by absence of the septum pellucidum. Coronal (B) and transverse axial (C) T2-weighted MRIs demonstrate bilateral transmantle clefts (arrowheads), lined by polymicrogyria (p) in addition to absence of the septum pellucidum. Transverse axial (D) T2-weighted image shows bilateral optic nerve hypoplasia.

Schizencephaly describes gray matter-lined clefts that extend from the ependyma of the lateral ventricles to the pial covering of the cortex. It is associated with vascular disruptions and, as in this case, clefts that are lined with polymicrogyria. Optic nerve hypoplasia is seen in up to one-third of patients with schizencephaly. Along with absence of the septum pellucidum, this constellation is consistent with septo-optic dysplasia.