Delayed leukoencephalopathy after carbon monoxide poisoning presenting as subacute dementia

We herein report the case of a 65-year-old woman who presented with the subacute onset of dementia and subsequently developed abnormal behavior and a gait disturbance. Her condition transiently improved; however, within one month, she became drowsy and poorly responsive, with limb chorea and urinary incontinence. Her history of frequently using charcoal led us to diagnose her with carbon monoxide (CO) poisoning. The findings of this case and a literature review suggest that subacute dementia due to CO poisoning recovers late, after a year or more, in patients above sixty years of age, and both hyperbaric oxygen and corticosteroid pulse therapy should be considered in such cases, even after one month.