Classification of epileptic seizures: a hospital-based study of 1,250 patients in a developing country

The 1981 International Classification of Epileptic Seizures (ICES) was used to study the distribution of seizure types in 1,250 patients attending an Epilepsy Clinic in Sri Lanka. Based on seizure symptomatology 94.6% of the cases could be classified, and by adding the routine interictal EEG findings the percentage of classifiable seizures increased to 97%. Partial seizures (73.8% cases) were three times as common as generalized seizures (23.3% cases). Of the partial seizures, simple partial seizures (SPS) accounted for only 0.4% cases, and complex partial seizures (CPS) for 8.8%, whereas partial seizures secondarily generalized (PSGS) accounted for 64.6%. PSGS had simple onset in 12.5% and complex onset in 34.8% of cases. Myoclonic seizures were the commonest of the generalized seizures, accounting for 14.6% of all cases. Tonic-clonic seizures accounted for 7.4% of cases; absence seizures accounted for only 1.3%. The study showed the 1981 ICES to be relevant and applicable in a clinical setting with limited investigatory facilities. Difficulties encountered with regard to certain subcategories could be overcome with minor modifications which made the classification operative. Routine EEG confirmed the diagnosis in a significant number of cases but changed the diagnosis in only a few, confirming that a good standardized questionnaire is the key instrument for classifying epileptic seizures.