The Gerstmann syndrome in Alzheimer's disease.

Background: It remains unclear from lesion studies whether the four signs of the Gerstmann syndrome (finger agnosia, acalculia, agraphia, and right-left confusion) cluster because the neuronal nets that mediate these activities have anatomical proximity, or because these four functions share a common network. If there is a common network, with degeneration, as may occur in Alzheimer's disease, each of the signs associated with Gerstmann's syndrome should correlate with the other three signs more closely than they correlate with other cognitive deficits.

Methods: Thirty eight patients with probable Alzheimer's disease were included in a retrospective analysis of neuropsychological functions.

Results: The four Gerstmann's syndrome signs did not cluster together. Finger naming and calculations were not significantly correlated. Right-left knowledge and calculations also did not correlate.

Conclusions: The four cognitive functions impaired in Gerstmann's syndrome do not share a common neuronal network, and their co-occurrence with dominant parietal lobe injuries may be related to the anatomical proximity of the different networks mediating these functions.