PERIVENTRICULAR AND SUBCORTICAL NODULAR HETEROTOPIA - A STUDY OF 33 PATIENTS

Grey matter heterotopias, demonstrated by MRI, may present with a broa d spectrum of clinical severity. We have studied 33 patients with peri ventricular nodular heterotopias (PNH); 19 (58%) had unilateral and 14 (42%) bilateral lesions. Thirteen of the 19 patients (68%) with unila teral subependymal nodules of grey matter had in addition, unilateral focal subcortical heterotopias (SNH), comprising 39% of the entire gro up. Most had normal intellectual and motor function but some presented with mild mental retardation and neurological deficits. Recurrent sei zures were described in 82%, mainly partial attacks with temporopariet o-occipital auras. Nodular heterotopias led to unilateral or bilateral independent temporal epileptic discharges in 47% of epileptic patient s with PNH alone and in 61% of those who had SNH in addition. Extratem poral or multilobar, unilateral or bilateral interictal spiking was pr esent in 10 other patients (36%). Two first degree relatives of patien ts with seizures were affected but had no seizures, three were investi gated for other apparently unrelated neurological symptoms: memory imp airment, vertigo or transient ischaemic attacks in one pet-son each. C ontiguous ovoid nodules of grey matter symmetrically lining both later al ventricles, were described in nine patients. Seven of them were fem ale, including four with familial incidence of PNH. Such lesions may e xplain the familial occurrence of epilepsy in some families., Seven pa tients underwent anterior temporal resection: two patients with unilat eral subependymal and focal subcortical heterotopias were seizure free or significantly improved. Four patients, three with PNH alone and on e with additional subcortical nodules, did not improve significantly a fter surgery. The remaining patient was followed for less than 6 month s.