The yield of routine outpatient electroencephalograms in the veteran population.

The objective of this study is to determine the yield of routine outpatient electroencephalogram (EEG) in the diagnosis of epilepsy in the veteran population. All consecutive outpatient EEGs at the James A. Haley Veterans Affairs Hospital in Tampa, FL from October 31, 2005, to October 30, 2007, were retrospectively reviewed. During the 2 years of the study, 636 routine outpatient EEGs were performed at James A. Haley Veterans Affairs Hospital. The age range for the patients was 21 to 97 years with a mean age of 55 years. Eighty-five EEGs (13.4%) were classified as abnormal. Nineteen EEGs (3%) in the past 2 years contained epileptiform abnormalities. Sixtyeight EEGs (10.7%) had other abnormalities such as slowing, asymmetry, excessive beta activity, or a combination of abnormalities. Thirty-six EEGs (5.7%) clearly demonstrated psychogenic nonepileptic attacks as documented by normal EEG and video recording of the patient's habitual event. Single routine outpatient EEG has been reported to have a sensitivity of 29% to 55% in detecting interictal epileptiform discharges in patients with a suspected diagnosis of epilepsy. In our study, only about 3% of the patients had clear abnormalities suggestive of epilepsy. Interestingly, by using routine EEGs, we were able to definitively diagnose more patients with psychogenic nonepileptic attacks than epileptic seizures.