The audiovestibular manifestations as early symptoms of multiple sclerosis: a scoping review of the literature

Background: Multiple sclerosis (MS) is an immune-mediated, demyelinating disease of the nervous system, which may impact the audiovestibular pathway at different stages of the disease. The auditory and vestibular manifestations of MS as a presenting or early symptom are an area in which more investigation is needed. Aims: The aim of this review is to determine the auditory and vestibular symptoms, which may occur at the presenting stage of multiple sclerosis. This clinical knowledge will allow a clinician to facilitate early diagnosis and intervention of MS through appropriate onward referral. Audiological and vestibular test results, as well as magnetic resonance imagery results, will also be examined to try to determine the impact of MS on the auditory and vestibular pathways. Methods: A scoping search of the electronic databases PubMed, Scopus, Web of Science, ScienceDirect, and EBSCO was conducted in March 2020 to obtain studies specifically of patients with audiovestibular symptoms at the early or presenting stages of multiple sclerosis. Data was extracted from studies which met the inclusion criteria and studies were subsequently critically appraised and assessed for risk of bias. Results: Eighteen papers met the inclusion criteria for this study. Results of the study found that the most common audiovestibular manifestation as a presenting symptom of MS was unilateral, moderate-profound, fluctuating, and sudden sensorineural hearing loss across all frequencies (250 Hz–8000 Hz). Other symptoms include tinnitus, balance abnormalities, aural pain and aural fullness, which may accompany SSHL or occur independently. The peripheral involvement of the immune-mediated mechanisms of MS was suggested by peripheral findings in vestibular examination results and the involvement of wave I ABR in patients with irreversible hearing loss. Demyelinating lesions associated with MS were suggested by results obtained from evoked potentials measurements, including ABR, VEMPs, and MLR. Conclusion: An understanding of the sensitivity of evoked potentials in the detection of demyelinating lesions as well as the most common audiovestibular presentations of the disease allows the practitioner to provide an appropriate onward referral for MRI which may lead to early diagnosis and intervention of MS. We suggest that there is enough evidence to include evoked potentials complementary to MRI in the detection and monitoring of MS. As the review suggests evidence of involvement of the immune-mediated mechanisms of MS on peripheral structures like the inner ear, further clinical research is recommended to explore this mechanism.Key points4. This is the first paper to support the theory (Di Stadio et al. 2018) [32] that immune-mediated processes of MS can spread to peripheral inner ear structures.