The prognosis for seizure control in newly diagnosed epilepsy.

We assessed the prognosis for seizure control in 106 patients who were referred to an adult neurology clinic with previously untreated tonic-clonic, partial, or mixed seizures and were followed prospectively for a median of 66 months (range, 6 to 96). Twenty-six patients remained completely free of seizures for as long as they were followed. Actuarial analysis showed that 35 per cent of patients could be expected to enter a seizure-free period of at least two years at the start of treatment, 73 per cent would have had a two-year seizure-free period at the end of four years, and 82 per cent would have had a two-year seizure-free period at the end of eight years. Of 79 patients whose seizures were completely controlled for at least two years, 51 subsequently remained seizure-free. If seizures continued for up to two years after the start of treatment, the probability of subsequent seizure control fell by half. The presence of partial seizures; a high frequency of tonic-clonic seizures before treatment; a neurologic, social, or psychiatric handicap; and a family history of epilepsy each indicated a worse prognosis. We conclude that the long-term pattern of seizure control is largely established during the first two years of treatment.