Prognostic and electroclinical features of grand mal epilepsies

We studied the electroclinical features and prognosis of 103 patients with tonic-clonic seizures alone. Patients were classified into three groups according to seizure semiology and interictal EEG: primary grand mal, focal grand mal and indeterminate grand mal. Discriminant analysis showed that a number of other electroclinical features had no significant classificatory power. Patients have been followed for 2-10 years. At the last observation 40% of patients were free from tonic-clonic seizures and 23% had fewer than 1 seizure a year, without differences among the three groups. The appearance of 'minor' (absence or partial) seizures during follow-up occurred in 12 patients and did not change the prognosis of tonic-clonic seizures. At the end of follow-up, 96% of patients had a normal social adjustment. Grand mal epilepsies therefore appear to have a good prognosis.