Marked Cognitive and Activities of Daily Living Improvement by Shunt Embolization in a Very Old Man with Portosystemic Encephalopathy Mimicking Alzheimer Disease: A Case Report.

A 91-year-old man with chronic cognitive impairment underwent shunt embolization for portosystemic encephalopathy (PSE). He experienced intermittent episodes of impaired consciousness and decreased cognitive function and activities of daily living (ADL), for which Alzheimer disease was suspected. On admission, he was in a coma and PSE was diagnosed based on his high ammonia level and the computed tomography findings. After shunt embolization, the patient fully recovered from the impaired consciousness and experienced no recurrence. The patient's Revised Hasegawa Dementia Scale and Mini-Mental State Examination scores improved significantly from 12 and 17 to 30 and 29 points, respectively. The Barthel Index score also improved from 55/100 to 85/100, suggesting a marked improvement in ADL. PSE progresses slowly in very old patients and may mimic the clinical course of Alzheimer disease but without liver enzyme abnormalities. Therefore, it should be distinguished in every dementia case.