Auditory neglect and right parietal cortex.

Many patients who have suffered right hemisphere stroke seem initially unresponsive to voices and environmental noises that emanate from their left (Heilman and Valenstein, 1972). The question of whether more subtle deficits might persist post-acutely, and whether, like visuospatial neglect, they really are more common after right than left hemisphere damage, has been comparatively little studied. Until fairly recently, auditory neglect was the poor relation of visual neglect. In part, this is because there are no auditory analogues of simple search tasks such as target cancellation, or of drawing or copying. Auditory bisection performance, where the subject is required to point to a position in space midway between two sound sources, has been reported (Ruff et al ., 1981): patients with right parietal lesions were less accurate than those with any other lesion site in terms of absolute error, but did not show a specific bias to the right. In terms of testing at the bedside, many examiners look for auditory extinction in a rough and ready fashion by clicking their fingers or jangling keys simultaneously on either side of the patient's head. The auditory subjective straight ahead (SSA) can also be tested without elaborate apparatus. When more sophisticated methods are used (e.g. presentation over headphones of stimuli with interaural and monaural cues to sound location in virtual space), the SSA is frequently found to show a large ipsilesional deviation in patients with left visual neglect after right parietal damage. It is important …