Distribution of seizure types in an epileptic population.

The distribution of seizure types was investigated in an epidemiological survey of 1,220 patients over 15 years of age. Classification of clinically dominant seizure type according to the International Classification of Epileptic Seizures (ICES) was possible in 1,005 cases (82.5%). Fifty-six percent of patients had partial seizures and 26.5% had generalized seizures. Subclassification of partial seizures revealed simple partial seizures (SPS) in 7.5% of the cases, complex partial seizures (CPS) in 23%, and partial secondarily generalized seizures (PSGS) in 25.5% of the cases. Simple partial onset was seen in 56% of the patients with CPS, and impairment of consciousness at the onset occurred in the remaining 44%. PSGS started with simple partial onset in 92% of the cases and the remaining 8% started with a complex partial phase. Tonic-clonic seizures were the most common type of generalized seizures, accounting for 23% of all and 88% of generalized seizures. Absence seizures were seen in 1% of the cases. A single seizure type was observed in 737 patients (60%) and the remaining 40% had multiple seizure types. SPS, CPS, and absence seizures were most commonly combined with other seizure types. The study revealed that distribution of seizure type varies as a function of age. Although the present study finds ICES relevant, difficulties in its utilization in epidemiological context are demonstrated.