Abstracts

Rationale: Electroencephalography (EEG) has been a valuable tool for diagnosing neurologic diseases. With the advances in neuroimaging, the role of EEG has been evolving. The purpose of this study was to analyze the characteristics of routine EEGs performed in an academic EEG laboratory of a level four epilepsy center. Methods: All adult patients who underwent routine EEG at Tampa General Hospital (TGH), a teaching hospital of the University of South Florida with 1018 beds, were included in this study. The study period was 3 months: January 1st to March 31st, 2012. Patients medical records including demographic data and EEG reports were reviewed. Results: A total of 432 adult patients (217 males) were studied. Patients mean age was 58. Of them, 372 (86%) were inpatients (192 males). The top five admitting specialties were internal medicine (222 patients, 60%), neurology (36 patients, 9.7%), neurosurgery (20 patients, 5.4%), cardiology (12 patients, 3.2%), surgery (10 patients, 2.7%) and pulmonary (10 patients, 2.7%) respectively. Inpatient: 237 of 372 inpatients had an abnormal EEG (64%) showing: non-epileptiform abnormalities including intermittent generalized slowing, continuous generalized slowing, intermittent focal slowing, asymmetry (207 patients, 56%); normal (133 patients, 36%); epileptiform discharges including spikes, polyspikes, sharp waves, spike-wave complexes, PLEDs, Bi-PLEDs (22 patients, 5.9%). Of these 22 patients, 1 patient was diagnosed with nonconvulsive status epilepticus and 1 with partial motor status epilepticus. 6 patients (1.6%) had a normal EEG and typical events were recorded which were determined to be psychogenic non epileptic attacks. 4 patients (1.1%) had EEG evidence of sleep onset rapid eye movement (SOREM). The 6 remaining EEG reports included: 4 with excessive beta, 1 with alpha coma, and 1 with electrocerebral silence. 11 patients had 2 EEG performed during this study period. Outpatient: 18 of 60 outpatients had an abnormal EEG (30%) showing: non-epileptiform abnormalities (10 patients, 17%); normal (42 patients, 70%); epileptiform discharges (6 patients, 10%). No patients were found to be in status epilepticus. 4 patients were determined to have psychogenic nonepileptic attack (5%); 2 patients (3.3%) had SOREM. No additional category of abnormality was included in the outpatient group. 2 patients had 2 EEG performed during this 3-month study period. Conclusions: On routine EEG, non-epileptiform abnormalities were predominant in inpatient population, while normal was the most frequent in the outpatient population. Psychogenic attacks and sleep-onset REM were more frequent in the outpatient population.