Persistent synchronous periodic discharges caused by anoxic encephalopathy due to cardiopulmonary arrest

We report a patient with vegetative state induced by anoxic encephalopathy due to cardiopulmonary arrest who showed synchronous periodic discharges for a prolonged period. The patient was a 47-year-old man admitted to our hospital for depression, who suddenly developed cardiopulmonary arrest of unknown etiology, and entered chronic vegetative state as a result of anoxic encephalopathy. Electroencephalography (EEG) revealed that synchronous periodic discharges were present for up to 5 months. The wave pattern, periodicity and duration of appearance of synchronous periodic discharges were similar to those of synchronous periodic discharges in Creutzfeldt-Jakob disease (CJD). The periodicity of synchronous periodic discharges was gradually prolonged, with the course again similar to the discharges in CJD. The mechanism of occurrence is considered to be similar to that of synchronous periodic discharges in CJD.