NeuroCase 1.

A 72-year-old right-handed male with a history of atrial fibrillation and chronic alcoholism is evaluated for dementia. His son gives a history of a stepwise decline in the patient’s function over the last 5 years with the accumulation of mild focal neurologic deficits. On examination he is found to have a pseudobulbar affect, mildly increased muscle tone, and brisk deep tendon reflexes in the right upper extremity and an extensor plantar response on the left. The history and examination are most consistent with which of the following?

A. Binswanger’s disease

B. Alzheimer’s disease

C. Creutzfeldt-Jakob disease

D. Vitamin B12 deficiency

E. Multi-infarct dementia

The answer is E. All the choices given in the question are causes of or may be associated with dementia. Binswanger’s disease, the cause of which is unknown, often occurs in patients with long-standing hypertension and/or atherosclerosis; it is associated with diffuse subcortical white matter damage and has a subacute insidious course. Alzheimer’s disease, the most common cause of dementia, is also slowly progressive and can be confirmed at autopsy by the presence of amyloid plaques and neurofibrillary tangles.

Creutzfeldt-Jakob disease, a prion disease, is associated with a rapidly progressive dementia, myoclonus, rigidity, a characteristic EEG pattern, and death within 1 to 2 years of onset. Vitamin B12 deficiency, which often is seen in the setting of chronic alcoholism, most commonly produces a myelopathy that results in loss of vibration and joint position sense and brisk deep tendon reflexes (dorsal column and lateral corticospinal tract dysfunction).

This combination of pathologic abnormalities in the setting of vitamin B12 deficiency is also called subacute combined degeneration. Vitamin B12 deficiency may also lead to a subcortical type of dementia. Multi-infarct dementia, as in this case, presents with a history of sudden stepwise declines in function associated with the accumulation of bilateral focal neurologic deficits. Brain imaging demonstrates multiple areas of stroke.