Usefulness of screening EEGs in a psychiatric inpatient population.

Many clinicians presume that a screening electroencephalogram (EEG) is useful in differentiating psychiatric from neurologic disorders. In a retrospective review of 698 charts of psychiatric inpatients, the authors assessed the usefulness of screening EEGs. Usefulness was defined as leading to a change in diagnosis or treatment. While 31% of screening EEGs were abnormal, only 1.7% of cases led to a change in diagnosis that might otherwise have been missed. It is unclear whether the EEG is a useful screening test on the basis of these results. Caution is warranted in interpreting these results because of the inaccuracies inherent in any retrospective review. Prospective studies are needed to better define EEG's usefulness in psychiatry.