The purpose of this study is to characterize the central auditory processing (CAP) deficits that result from multiple sclerosis (MS).

Five general types of evaluations will be employed over multiple study sessions at the National Center for Rehabilitative Auditory Research (NCRAR). First, a neurologist will review the subject's medical history and perform a neurologic exam to confirm MS diagnosis. Second, peripheral auditory function will be evaluated using a standard set of routine audiometric tests. Additionally, subjects will complete a case history and series of hearing handicap inventories. Third, a battery of behavioral procedures will be used to characterize central auditory processing. Fourth, auditory evoked potential studies will be performed. Emphasis here will be upon evoked potentials whose putative neural generators lie within the central auditory nervous system. Fifth, subjects will receive magnetic resonance imaging (MRI) evaluation to determine sites and amount of neural degeneration.

Inclusion Criteria:

• age 21-65 years;
• a clinical or laboratory supported diagnosis of "definite" MS;
• a diagnosis of relapsing-remitting, primary progressive, or secondary progressive MS;
• a Kurtzke Expanded Disability Status Score (EDSS) of 0 to 7.0, inclusive;
• no history of a clinical relapse or change in EDSS for three months preceding entry into the study; and
• a brain MRI scan that shows at least three white-matter lesions on T2-weighted images consistent with MS

Exclusion Criteria:

• current major disease or disorder other than MS (e.g., cancer, end-stage renal disease, end-stage cardiopulmonary disease, post-traumatic stress disorder, diabetes);
• other neurological conditions that could interfere with the ability to respond to tests and questionnaires;
• non-native speaker of English (since test materials are presented in English);
• pregnant (due to potential negative effects on the fetus during fMRI);
• more than a mild degree (less than a 40 dB HL four-frequency pure-tone average [PTA]) of hearing loss bilaterally (since the presence of more than a mild degree of peripheral hearing impairment may impact CAP test results);
• metal implants (due to fMRI constraints); and
• left-handedness