Amnesia After Carbon Monoxide Poisoning

Mr. A, a 22-year-old man, was seen after a suicide attempt. A breakup with a girlfriend led to depression. He routed the exhaust from his vehicle into the passenger compartment. After he was discovered, he was sent for emergency hyperbaric oxygen treatment and then transferred to the medical ward.

I was initially relieved to observe Mr. A’s pleasant affect. He returned my greeting readily and cooperated fully. He was able to relate his history through age 18, with salient facts verified by family members. But then his story stopped completely. He had no memory of any events after his 18th year. During formal testing, he was able to repeat words accurately but could not recall any new material once his attention was diverted to other tasks. He had no knowledge of his current surroundings and no memory of his lost relationship, his recent depression, or his suicide attempt. When I asked him about any current suicidal intent, he smilingly denied such thoughts and asked why I would need to ask such a question. Mr. A was locked in the present. He could not learn new facts about his environment or himself.

This unfortunate young man was suffering from anterograde and retrograde amnesia. It was notable that the balance of his examination was normal, including his euthymic affect. Magnetic resonance imaging revealed bilateral hippocampal infarcts. Other than his profound memory deficits, the results of his mental status examination were normal.

When I returned the next day, Mr. A again greeted me pleasantly and did not appear depressed, nor did he remember me. During formal testing, his deficits were found to be unchanged. It was striking to me how Mr. A did not appear depressed, despite evidence that he had been significantly depressed before his suicide attempt. Barring an unanticipated recovery, I suspected he would feel himself forever to be 18.

His family members, initially relieved by his having survived, were devastated by the explanation of amnesia and his poor prognosis. They understood the need for a transfer to a rehabilitation facility after discharge.