The role of EEG in patients with syncope

EEG is a popular, low-cost examination used in neurologic and nonneurologic evaluations. Nevertheless, the diagnostic usefulness of EEG has some limitations, and it may increase medical costs. The manifestations of syncope may lead to misdiagnoses, and frequently, it is mislabeled as epilepsy. An EEG is usually obtained, yet some studies have suggested that EEGs have little value in diagnosing this condition. We aimed to determine the diagnostic usefulness of EEG in patients with syncope. We retrospectively examined EEG recordings of 10,408 patients. EEG findings were evaluated for all patients with a diagnosis of syncope (syncope, convulsive syncope, loss of consciousness, or sudden unexplained falls), including requests from neurologists and nonneurologists. EEGs were classified into (1) normal, (2) epileptiform discharges (spike/sharp waves), and (3) slow waves. The EEGs were separated according to gender and age. From 1,003 patients with the diagnosis of syncope, 899 (89.53%) were normal, 62 (6.18%) showed bilateral slow waves, 19 (1.89%) right slow waves, 18 (1.79%) epileptiform discharges, and 6 (0.6%) left slow waves. Epileptiform discharges only occurred among females. Left focal sharp waves were disclosed in 18 (50%), generalized discharges in 8 (44.4%), and right focal discharges in 1 (5.6%). Bilateral slow waves were more prevalent among adults. We conclude that EEG is not useful for evaluating the diagnosis of syncope because of its very low diagnostic yield. Patients with syncope must have a correct history and physical examination plus cardiovascular tests.