Metabolic encephalopathy (suspected) (EEG)

This 64-year-old patient had undergone chemotherapy with melphalan and then total-body radiation prior to autologous stem cell transfusion for multiple myeloma. He was noted to have an altered mental status about 2 weeks later. His Glasgow Coma Score was 2/2/4 = 8. Neurologic examination showed no abnormalities other than the altered mental status. The patient was febrile, but no source of infection was found despite pan-culturing that included cerebrospinal fluid. Liver enzymes, ammonia, sodium, calcium, and magnesium were normal. MRI of the brain was also normal. The EEG showed moderate (mixed theta and delta activity) slowing and triphasic waves. The EEG was reactive to noxious stimulation. The EEG confirmed the encephalopathy and excluded depression or other non-neurologic cause for the mental status abnormality. The patient recovered. No follow-up EEG was performed. (Contributed by Dr. Jeffrey Nicholl and Dr. David Gloss.)