Visual syndromes as the presenting feature of degenerative brain disease.

The symptoms of a degenerative brain disease are dictated by its topography. Visuo-spatial impairment may be a severe and early feature of degenerative dementia. Visual symptoms in such patients are broadly divisible into dorsal and ventral visual syndromes, which result from a degenerative focus in occipito-parietal and occipito-temporal visual association cortices, respectively. The dorsal visual syndrome includes asimultanagnosia and Balint's syndrome. The ventral visual syndrome includes alexia and visual agnosia (prosopagnosia). Less often, hemineglect or visual field defects result. When Alzheimer's disease and Creutzfeldt-Jakob disease present in this way there is a topographic shift of neurodegenerative changes to posteriorly situated cortices. Patients with corticobasal ganglionic degeneration often develop symptomatic involvement of contiguous sensorimotor cortices causing mixed perceptual-motor syndromes. Even in patients with more typical patterns of dementia, the degree of visuo-spatial impairment may hinder driving skills, and the issue of driving should be addressed early in the clinical course.