The prognostic value of the EEG in 120 seizure-free epileptic patients, during and after antiepileptic drug withdrawal, was analyzed at the Department of Neurology, University of Bologna, Italy. Of 128 patients studied with mean age of 28 years, 49 had complex partial seizures (CPS), and 20 had simple partial seizures. Patients included had a history of partial epilepsies treated with AEDs for at least 2 years, and were seizure-free for at least 2 but not more than 6 years. Overall, 75 (63%) relapsed within 3 years from complete drug withdrawal, 29 during drug reduction. Of 36 (30%) showing EEG epileptiform abnormalities at the start of the study, 16 showed an increase in EEG abnormality during and after drug withdrawal. Of 84 with normal EEGs initially, 20 showed epileptiform abnormalities with drug withdrawal. The lowest relapse rate occurred in CPS patients (45%) and the highest in those with SPS (100%). The EEG at the start of the study was not predictive of relapse, but EEG worsening during the withdrawal of AEDs was associated with a significantly higher relapse rate. [1]

COMMENT. In this study of young adults with partial epilepsies, the EEG was predictive of relapse during but not before starting the withdrawal of antiepileptic drugs, especially if abnormalities appeared when previously absent.

Similar studies in children have not included large numbers of partial epilepsies, but some have indicated a higher relapse rate in female, mentally retarded children with focal neurologic signs and partial seizures. For further reports of the EEG and AED withdrawal see Progress in Pediatric Neurology I, PNB Publ, 1991, pp100-104; and Ped Neur Briefs Dec 1995;9:90. In this 1995 Japanese study, Murakami M et al found a relapse rate of 20% in symptomatic partial epilepsies and 8% in idiopathic partial epilepsies in children. Age dependent factors were important in predicting relapse, peaking at 17 to 19 years for symptomatic partial seizures. Background activity in the EEG was also a predictive factor, the risk of relapse being greater with persistence of slow waves and decreased alpha activity.