AUDITORY TEMPORAL RESOLUTION IN MULTIPLE-SCLEROSIS

Disturbances of hearing in multiple sclerosis patients have been varia bly reported, likely because standard audiologic testing emphasizes as sessment of peripheral, rather than central, auditory function. This s tudy investigated a group of patients with multiple sclerosis (MS), pr ospectively selected on the basis of magnetic resonance imaging (MRI) scans. Five of these patients had demyelinating lesions that included the rostral auditory fibre tracts, while another seven patients had le sions restricted to brainstem auditory sites. A further four had no le sions in the distribution of their auditory pathways. A comprehensive battery of audiometric tests, including standard audiometry and retroc ochlear testing, was performed. In addition, their findings on electro physiologic testing, including auditory brainstem responses (ABR) and middle latency responses (MLR), were studied. Finally, their performan ces in gap detection and speech recognition in continuous and interrup ted background noise were examined to assess their auditory temporal r esolution. The MS patients were found to be selectively impaired under the interrupted masker of this speech-in-noise paradigm, confirming a temporal processing defect. Furthermore, these patients' performances suggested a predominant role of forebrain pathways in mediating audit ory temporal resolution.