Abstracts

Recently, focal transmantle dysplasia has been proposed to be a specific malformation of cortical development resulting from abnormal stem cell proliferation. It is characterized by abnormal brain tissue extending through the entire mantle of the cerebrum from the cortex to the ventricular surface.
We investigated the clinical and imaging features in 5 epileptic patients with focal transmantle dysplasia (3 men and 2 women, mean age 29 years).
All patients had no significant risk factor for epilepsy. Neurological examination was normal in 4 of 5 patients. One had congenital nystagmus. Simple partial seizures were in 2 patients (secondary generalization in one), nocturnal secondary generalized seizures in 2, nocturnal unclassified seizures in one. Seizure onset was between the ages of 8 and 32 years (mean 19 years). EEG showed the localized epileptiform discharges in 2 patients. On MRI, all patients had signal abnormality extending from the posterior frontal cortex to the superolateral wall of the lateral ventricle. The lesion signal was homogenous and isointense to gray matter. There was no contrast enhancement. The lesion was in left hemisphere in 4 out of 5 patients. The lesion was slightly protruded into lateral ventricle in 3 patients. Three patients were accompanied with other anomalies. One patient had agenesis of septum pellucidum, septo-optic dysplasia, hypoplasia of corpus callosum, and cortical dysplasia with arachnoid cyst in contralateral hemisphere. The other 2 patients had agenesis of septum pellucidum. Seizure outcome to anticonvulsants was variable.
The characteristic MRI features can identify and differentiate focal transmantle dysplasia from other malformations of cortical development. It can be associated with other anomalies, especially with agenesis of septum pellucidum.