History

A 76-year-old man, a university educated retired engineer, was referred with a 2-month history of deteriorating balance and memory. He took metformin for type 2 diabetes mellitus. He attended with his wife within 2 days of the referral and brought his recent MRI scans of the brain and abdomen. He was not concerned by any memory problems (his wife certainly was), but felt off-balance when walking. It became apparent that he had actually been losing balance and memory for about 12 months, but this had progressed more rapidly in the last 2 months. He had no headaches, sensory or urinary symptoms. He was sleeping and eating well and had not lost weight. He was an accomplished pianist and his musical abilities had not deteriorated. He had never smoked and drank little alcohol.

Examination

His wife said that he was his usual jocular self—possibly even fatuous. General examination, including heart, chest and abdomen, was normal. There was no cranial nerve abnormality, no papilloedema, no muscle wasting, normal muscle tone and strength throughout; reflexes were normal in the upper limbs, but knee jerks and ankle jerks were absent. His right plantar was extensor. Sensation was intact to pinprick; there was slight impairment of vibration and position sense at the toes. He walked with a wide-based unsteady gait and could not tandem walk; Romberg's test was positive. He scored 22/30 on the Mini-Mental State Examination, losing points for orientation, memory (recall) and repetition. On the Addenbrooke's Cognitive Examination he scored 62/100, losing points on memory (recall, anterograde and retrograde). Verbal fluency was decreased. Language, naming and comprehension were intact. His scores were: attention and orientation 14/18, memory 10/26, fluency 0/14, language 24/26, visuospatial 14/16.

The MRI scan of brain (figure 1) he brought with him had been reported as follows: ‘There is moderate cerebral atrophy with prominence …