# Hearing Loss in Neuromyelitis Optica Spectrum Disorder: Case Report and Systematic Review

## TL;DR

This paper reports a rare case of hearing loss in a patient with Neuromyelitis Optica Spectrum Disorder and reviews existing literature to better understand this unusual symptom.

## Contribution

The paper presents a rare case of peripheral auditory pathway involvement in NMOSD and expands understanding of its clinical presentation.

## Key findings

- Hearing loss in NMOSD is rare and often occurs during relapses, with most cases being AQP4-positive.
- Hearing loss can be isolated or combined with tinnitus, ataxia, and vomiting, and may be the initial symptom.
- High-dose steroids and plasmapheresis were used as treatments, with variable effectiveness in improving hearing.

## Abstract

Background: Sudden, non-traumatic hearing loss has been associated with vascular or inflammatory disorders. Hearing loss in Neuromyelitis optica spectrum disorder (NMOSD) is a very rare presentation. Methods: In this paper, we describe the case of a 58-year-old female patient with aquaporin-4-positive NMOSD exhibiting bilateral tinnitus and right-sided deafness in the context of a relapse. The auditory brainstem responses pointed to a lesion of the right peripheral auditory pathway (cochlea and/or auditory nerve). The patient’s hearing failed to improve after high-dose intravenous steroids; however, it showed slight improvement after plasmapheresis. We also conducted a systematic literature review in databases MEDLINE and Scopus in English, searching for all reported cases of hearing loss in NMOSD. Results: We included 10 studies reporting 15 cases of NMOSD with hearing loss. The vast majority of patients were female (11 out of 15, 73.3%), with an age range of 26 to 70 years. Hearing loss, ranging from mild to severe, seems more frequent in AQP4-positive cases, and it can even be the presenting symptom. It can present isolated or in combination with tinnitus, ataxia, and/or intractable vomiting. The auditory pathway impairment in NMOSD seems to be localized either centrally, i.e., cochlear nuclei or higher brainstem levels, or peripherally, i.e., in the cochlea or cochlear nerve itself. Intravenous methylprednisolone in high doses, followed by oral tapering, was the most common treatment option, resulting in a gradual improvement. Conclusions: This paper describes a rare case of peripheral auditory pathway affection in NMOSD, which is an inflammatory astrocytopathy mainly affecting the central nervous system. Early recognition of hearing loss in the context of an NMOSD relapse and subsequent treatment have a crucial impact on the hearing outcome of NMOSD patients. This expands our knowledge of NMOSD as an autoimmune aquaporin-4 channelopathy.