Malformations of cortical development (MCDs) and epilepsy: Experience from a tertiary care center in south India

INTRODUCTION Malformations of cortical development (MCDs) are increasingly recognized as important cause of epilepsy, especially refractory epilepsy. In developing countries like India, where the facilities for sophisticated imaging are not easily accessible to all, the prevalence and the types of cortical malformations are largely unknown. Hence this preliminary study has been undertaken to examine the relation between epilepsy and malformations of cortical development in a resource-limited setting. AIMS To study various types of malformations of cortical development (MCDs) associated with epilepsy and to correlate with their clinical semiology. SETTINGS AND DESIGN The study was conducted in a tertiary care neurological center in south India. Cohort included all patients with epilepsy associated with cortical malformation on neuroimaging. METHODS AND MATERIALS Neuroimaging data of all patients with epilepsy were evaluated for a 5-year period from 1998 to 2003, for the presence of cortical malformations. The case records of those patients with cortical malformations were taken from the medical records department and the clinical and electrophysiological data were analyzed. RESULTS We are reporting 34 cases of MCDs evaluated during the 5-year period. The mean age of the cohort was 15.1 (+/-12.2) years, with a range from 3 months to 45 years and 52.9% were males. Mean age at seizure onset was 7.2 years (+/-7.8), with a mean duration of seizure of 8.1 years (+/-7.7). Delayed motor and mental milestones were present in 15 patients (44.1%) and positive family history of seizure/epilepsy was seen in 9 patients (26.5%). Cortical malformations were most often associated with partial seizures (19/34, 55.9%). The most common type of seizure was complex partial seizure, seen in 12 patients (35.3%). Majority had very frequent, uncontrolled seizures with 16 (47.1%) patients having a seizure frequency of more than one per day. Heterotopias were seen in 14 patients (41.2%), in isolation in 5 (14.7%) patients and in combination with other malformations in 9 (26.5%) patients. Pachygyria was present as an isolated anomaly in five (14.7%) patients and combined with other abnormalities in eight (23.5%) patients. Cortical dysplasia was seen in 5 (14.7%) patients, hemimegalencephaly in two patients, polymicrogyria in two patients, lissencephaly and schizencephaly were seen in one patient each. EEG demonstrated focal epileptiform discharges in 59.1%, while generalized epileptiform discharges were seen in 22.7% of patients. Twenty-seven out of 34 (79.4%) patients had refractory/difficult to treat epilepsy. CONCLUSIONS Malformations of cortical development are a heterogeneous group of disorders, associated with developmental delay and refractory seizures but seizures usually do not have pathognomonic semiologic features. Possibility of MCDs should be considered during the evaluation of refractory epilepsy cases.