Clinical Reasoning: A rapidly progressive thalamic dementia.

A 61-year-old White man with hypertension and diabetes presented to the emergency department with a 10-day history of excessive daytime sleepiness, confusion, mental slowing, memory loss, and behavioral changes. He had become apathetic and quieter with loss of initiative and showed reduction of spontaneous speech. No headache, fever, or recent infections were reported. Neurologic examination revealed hypomimia, mild parkinsonism (mild rigidity of the left arm, reduced bilateral arm swing during gait, global mild bradykinesia), confusion with partial disorientation in time and space, and short- and long-term memory impairment. Mini-Mental State Examination Scale score was 15. Cranial nerves, speech, language, motor, sensory, and cerebellar functions and reflexes were normal. Brain CT scan and arterial and venous CT angiography (CTA) were normal. The patient was admitted to our neurologic department for further management.