Intermittent EEG attenuations have relatively clear significance in pediatric populations, but a consistent clinical correlation has not been identified in adults. While generally seen in metabolic encephalopathies, the specific clinical correlates and prognostic value have not been determined. Methods: We prospectively collected 22 consecutive EEGs noted to have intermittent generalized attenuations. Baseline and discharge modified Rankin Scale (mRS), diagnosis at discharge, EEG altering

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... tions, ICU admissions, relevant imaging, mental status, the location the patient was discharged to, and pertinent lab values were assessed. Results: Mean patient age was 73.7 (SD=11.0) at admission. Twelve of the twenty-two patients (55%) died during their course in hospital. Four patients (18.2%) did not have a change in mRS score from baseline to discharge, while most had an increase in their mRS scores reflecting increased disability. Twelve patients (55%) were admitted to the ICU or CCU during their time in hospital. The most common etiologies were metabolic encephalopathies, and often associated with triphasic waves. Conclusions: Intermittent generalized EEG attenuations in adults are associated with severe metabolic encephalopathies and poor outcome including high association with mortality. The physiologic mechanism of generalized attenuations in poorly understood. Patients with this pattern should be suspected of having a severe metabolic encephalopathy and treated accordingly.