Pure sleep seizures: risk of seizures while awake.

PURPOSE: To estimate the risk of seizures while awake in pure sleep epilepsies - a long follow-up study. METHODS: Fifty five patients (60% male), with pure sleep epilepsy were followed up for at least ten years. Patients younger than 18 years of age were excluded. The primary endpoint was the occurrence of seizures while awake, after a period of 10 years or longer suffering from pure sleep seizures. RESULTS: The duration of the pure sleep seizures ranged from 10 to 67 years (median 22). The patients had been followed in our Department for a mean of 12 years. Patients' ages ranged from 18 to 88 years (median 50); 44% of patients suffered from apparently generalized seizures. Epilepsy was considered undetermined in 38.2%, focal cryptogenic in 38.2%, and focal symptomatic in 21.8%. There was a single case of idiopathic generalized epilepsy. In the last evaluation, 35 patients were on monotherapy and two were not receiving treatment. Seizure frequency was < 1/year in 65.5%; 1-10/year in 14.5%; > 1/month in 9.1%. Seventeen patients (30.9%) had suffered one or more seizures while awake. Multivariate analysis showed that sudden withdrawal of treatment (p < 0.032) and polytherapy (p < 0.18) were associated with an increased risk of seizures while awake. CONCLUSIONS: In spite of a small number of seizures and good response to monotherapy, a third of the patients studied suffered seizures while awake. The significant risk factors were sudden withdrawal of treatment and polytherapy.