Uncommon Hearing Instability Disorders: A Scoping Review

The aim of this scoping review is to identify and categorize uncommon disorders of hearing instability, enabling a better understanding of their clinical presentations and treatments.

The framework for the review was developed using the PRISMA-ScR. Literature was pulled from Medline, Web of Science, Embase, and Cochrane Central and screened independently by 3 reviewers with an extended inclusion and exclusion criteria. Once included, data extraction included etiological category of the disease, hearing loss type (sudden, fluctuating, or both), associated symptoms, comorbidities, treatments administered, and hearing recovery outcomes.

A total of 334 studies were included after screening, and data from 2247 patients was extracted. The most common etiologies per study were infectious (30.2%, n = 101 studies), neoplastic (29.6%, n = 99 studies), and vascular (28.1%, n = 94 studies). Average age across cases was 45.9 years (range: 0-90). Among patients, 89.8% exhibited sudden hearing loss, while 8.18% experienced fluctuating hearing loss. Neoplastic-related hearing instability had the highest number of total patients (n = 1101 patients), predominantly involving vestibular schwannomas (n = 582 patients) while infectious diseases had the second highest number of patients (n = 493 patients), with COVID-19 as the most reported infection (n = 146 patients). Causes identified without a known association with hearing loss in other literature include acute or chronic myeloid leukemia (n = 24), metastatic tumor disease (n = 10), or infective endocarditis (n = 3).

Hearing instability can arise from a variety of uncommon causes. Increased awareness of these conditions may help clinicians initiate appropriate treatment sooner, potentially improving patient outcomes.