Pure topographical disorientation due to a deep-seated lesion with cortical remote effects.

Lesions producing pure topographical disorientation syndromes are classically located either in the right parietal region either in the right parahippocampal gyrus. The patient described in the present study was admitted to hospital after sudden onset of a left hemiparesis. The lesion at CT scan was located in the posterior limb of the right internal capsule. Neuropsychological assessment was normal except for the presence of a major topographical disorientation and of mnestic disturbances for visuo-spatial material leading us to attribute topographical disorientation to a specific loss of topographical memory. Regional cerebral blood flow measurements disclosed a right parietal hypoperfusion. This remote cortical effect could account for the presence of the neuropsychological disorders.