The diagnostic aid of routine EEG findings in patients presenting with a presumed first-ever unprovoked seizure

Data are available on the yield of a single EEG recording in patients with epilepsy but there is little information on EEG findings as an aid in suppo rting the diagnosis of an epileptic event in patients presenting with a fir st-ever event suspected of being an unprovoked seizure. We retrieved files of patients above the age of 15 years admitted through the emergency room d uring 1991-1995 with presumed first-ever unprovoked seizure. There were 91 patients (age 50 +/- 24; 52 males), of whom 66% had a presumed seizure of u nknown origin and 34% had presumed remote symptomatic seizures. About 80% h ad generalized seizures (primarily or secondarily). In all the patients an EEG had been performed within 48 h of the event. Abnormal EEGs were obtaine d in 69%, with epileptiform activity in 21% (10% focal, 9% generalized and 2% focal and generalized), slowing in 58% (21% focal, 31% generalized and 7 % focal and generalized), and both epileptiform activity acid slowing in 10 %. Epileptiform activity was most common in younger patients with seizures of unknown origin, compared with older individuals with symptomatic seizure s (34, 38 vs. 27%, 7%, P = 0.001). We conclude that following a single unpr ovoked presumed seizure, adults commonly exhibit abnormalities in an EEG re corded close in time to the event. The EEG is particularly helpful in suppo rting the epileptic nature of the event in younger patients and in those wi th seizures of unknown origin. (C) 2000 Elsevier Science B.V. All rights re served.