Rapid recovery from coma with multifocal PLEDs in a patient with severe dementia and transient hypoxemia

We report a patient with severe dementia who acutely developed transient coma following possible acute anoxic encephalopathy, and presented multifocal periodic lateralized epileptiform discharges (PLEDs) on EEG, who had a good recovery from the acute state. Two EEGs were recorded from this patient. In the first EEG taken immediately after admission, multifocal PLEDs were prominent, and the background activity consisted of low voltage, continuous and irregular theta activity (4-6 Hz). The patient recovered from coma (GCS-3) to the conscious state (GCS-15) within 14 hours and was not associated with newly developed focal or global neurological deficits except for stable severe dementia which had developed in the previous several years. Another EEG taken 5 days later showed disappearance of multifocal PLEDs. Transient appearance of multifocal PLEDs might represent at least the transient, vulnerability associated with underlying dementia in this particular patient. We concluded that multifocal PLEDs do not always indicate a poor outcome in patients with possible acute anoxic encephalopathy, and rapid diagnosis and appropriate treatment should be done even if the initial EEG shows multifocal PLEDs.