Inter-ictal EEG patterns in malformations of cortical development and epilepsy

Objectives: Malformations of cortical Development (MCDs) are associated with refractory epilepsy. We evaluated scalp inter-ictal EEG patterns in various types of MCD, and its association with clinical features and seizure control. Patients and methods: Retrospective analysis of demographic, clinical, inter-ictal EEG and seizure outcome data of 665 patients with epilepsy and MCD with at least two years follow up was performed. Results: Average age of study population was 15.95 +/- 10.79 years with 291(43.8 %) women. Multiregional spikes were more common in children (22.7 % vs 8.5; p < 0.001), if age of onset of epilepsy was <= 2 years (21.8 % vs 11.4 %; p = 0.001) and polymicrogyria (12.1 % vs 37.3 %; p < 0.001). Generalized epileptiform discharges were more frequent in patients with developmental delay (24.7 % vs 12.6 %; p < 0.001); and were associated with lissencephaly(14.0 % vs 59.3 %; p < 0.001) and heterotopias(14.5 % vs 34.9 %;p = 0.002). Regional spikes were more common if age of onset of epilepsy is >= 2 years (26.2 % vs 38.4 %; p = 0.003), and also in FCD (17.1 % vs 42.6 %; p < 0.001). At latest follow-up, 151(22.7 %) patients were seizure free; 401(60.7 %) had refractory epilepsy and the rest had remissions with relapse. No association was found between inter-ictal EEG patterns and seizure control. Conclusion: In patients with MCD, generalized epileptiform discharges were associated with developmental delay, lissencephaly and heterotopias. Regional spikes were frequent in FCD while multiregional spikes in children and polymicrogyria. Inter-ictal EEG patterns did not influence seizure outcome.