Visuospatial disorders and related lesions of the brain.

Ten right-handed patients suffering from visuospatial impairment were examined. The impairment was ascertained by a test requiring visual organization (picture completion). The patients did not suffer from other neuropsychological disorders (e.g., aphasia, dementia). Furthermore, psychiatric symptoms and defective oculomotion (gaze paresis, ocular paresis) were controlled. CT scan data revealed that in 4 patients the impairment was associated with lesions of the posterior right hemisphere. All lesions involved the central optic pathways and were accompanied by visual field defects. On the other hand, 6 patients turned out as suffering from damage of the cerebellum or brainstem. The available electronystagmographical data revealed impaired visual fixation, an oculomotor defect characterizing gaze apraxia, the diagnostic marker of Balint's syndrome.