Auditory extinction following hemisphere damage.

Extinction to the simultaneous presentation of sounds to both ears was investigated in patients with acute cerebrovascular disease and found to be present in nearly half of the patients in the early stage of stroke. The occurrence of the symptom was not significantly different following damage to either hemisphere, but a higher percentage of right brain-damaged patients tended to show extinction for a longer time. However, this finding must be evaluated with caution since a greater number of left- than right-hemisphere patients had to be excluded from the investigation because aphasia precluded their understanding test instructions. The presence of auditory extinction was not related to that of visual extinction and there were patients with severe visual neglect who did not extinguish in the auditory modality. These findings and CT scan evidence, indicating that patients with long-lasting extinction had lesions encroaching upon the auditory pathways, suggest that in number of cases the phenomenon may have a sensory and not an attentional basis.