Pure topographical disorientation related to dysfunction of the viewpoint dependent visual system.

A 70-year-old woman presented with pure topographical disorientation following haemorrhage in the right medial parietal lobe. She could not navigate in the real world despite good ability to draw maps, describe routes, and identify objects and buildings. Her performance on mental rotation, visual memory, and spatial learning tests also was normal. In contrast, she failed totally in a locomotor map test and in a task in which she was requested to judge viewpoints of buildings. Her highly selective topographical disorientation was probably caused by the inability to identify a viewpoint of a particular building. The lesion may have disconnected the association between the spatial information processed in the lateral parietal lobe and the visual memory mediated by the limbic system, which seems to be important for viewpoint dependent analysis.