Subacute diencephalic angioencephalopathy--report of an additional case.

The following report presents an additional example of subactue diencephalic angioencephalopathy. The patient, a 68-year-old man, unexplicably withdrawn and asocial throughout his life, presented with an altered mental status of relatively recent onset. His illness was marked by progressive dementia and ended in death within 7 weeks. The neuropathologic findings were essentially identical to those described in the previous case in both their histology and topographic localization within the thalamus. The etiology, pathogenesis, and reason for the localization of this entity are unknown. Nevertheless, the lesion underscores the major role of the thalamus in cognitive function, emotional behavior, and awareness.