EEG abnormalities in nonepileptic patients.

A total of 202 nonepileptic patients (120 males and 82 females) who exhibited spike abnormalities at least twice in their EEG examinations were studied. The incidence of spike abnormalities among nonepileptic patients was 8.1% (847/10,473). The majority (90%) were under age 19. Headache, dizziness and vomiting, and abdominal pain were more frequently observed compared with controls. Mild paroxysmal EEG abnormalities such as diffuse irregular slow wave bursts with spike (27%), positive spikes (25%) or small spike (8.4%) were commonly detected. In three patients who developed epileptic seizures during the follow-up period, more specific EEG abnormalities were often exhibited. Other factors like the age at onset before 9, characteristic clinical symptoms or a positive family history of seizures were confirmed to be necessary for the manifestation of clinical seizures.