Background: Many multiple sclerosis (MS) patients with normal peripheral hearing suffer from difficulties in their hearing especially speech perception in background noise, which is possibly because of deficit of central auditory processing in this group.
Objective: To elaborate the effect of MS on central auditory processing.
Subjects and methods: Seven audiologic tests including masking level difference (MLD), auditory memory test (recognition, content and sequence), dichotic digit test (DDT), speech intelligibility in noise test (SPIN) and gap in noise test (GIN) as well as electrophysiologic assessment (speech evoked ABR c-ABR and P300) were used for comparing aspects of central auditory processing between MS patients and controls. Scores for each test obtained through cross-sectional non-invasive study conducted on 30 Egyptian subjects with relapsing-remitting MS who had mean age of 37.07 ± 11.43 years, and 30 controls with normal peripheral
hearing and mean age of 33.40 ± 9.38.
Results: This study demonstrated reduced MLD in MS at 500 & 1000 Hz in relation to controls. MS patients were worse than controls in recognition memory (pv = 0.011), memory for contents (pv <0.001) and memory for sequence (pv <0.001). in addition, low scores of DDT (version I & II) revealed in MS patients (pv = <0.001& 0.011 for I & II respectively), reduced SPIN test score in MS subjects (pv<0.001), elevated threshold and reduction of percent of correct answer obtained from GIN test in MS patients (Pv <0.001). Furthermore, in MS patients, there were prolonged latencies and reduced amplitudes of c-ABR waves and P300. In addition, significant differences were revealed between MS subjects and controls in all c-ABR measures analysis.
Conclusion: this study revealed apparent effect of MS on auditory processing.