Absence of the septum pellucidum. Overlapping clinical syndromes.

A patient with absence of the septum pellucidum, optic hypoplasia, congenital nystagmus, hemiatrophy, and seizures fulfilled clinical and radiological criteria for diagnosis of both septo-optic dysplasia and the syndrome of absent septum pellucidum with porencephalies. The anatomical and clinical similarities between these two syndromes suggest a common embryological basis. Their simultaneous presence in this case further supports this explanation. Clinically mild forms of both septo-optic dysplasia and the syndrome of absent septum pellucidum with porencephalies are now detected with the aid of computed tomographic scanning in patients with unexplained hemiatrophy, congenital nystagmus, seizures, and short stature.