- When sensorineural hearing loss occurs in the context of an inflammatory condition, it is referred to most appropriately as immune-mediated inner ear disease (IMIED).
- May be associated with disturbances of balance as well as hearing loss because the inner ear mediates vestibular function as well as hearing.
- May occur as a primary inner ear problem or as a complication of a recognized inflammatory condition such as Cogan syndrome, granulomatosis with polyangiitis (formerly Wegener granulomatosis), giant cell arteritis, Sjögren syndrome, and others.
- Symptoms include tinnitus, vertigo, nausea, and difficulties with two issues related to hearing: acuity and speech discrimination.
Sensorineural hearing loss (SNHL) is an idiopathic inflammatory disorder, either secondary to a known autoimmune disease or occurring as a primary form of disease limited to the ear. The anatomy of the inner ear is shown in Figure 68–1. SNHL is a common feature of some primary forms of vasculitis (eg, Cogan syndrome, granulomatosis with polyangiitis (formerly Wegener granulomatosis), giant cell arteritis). SNHL also occasionally occurs in association with systemic autoimmune disorders, such as systemic lupus erythematosus (SLE) and Sjögren syndrome. Finally, SNHL may represent an organ-specific inflammatory process confined to the inner ear. Injury to the stria vascularis associated with antibody deposition around vessels and vascular occlusion observed in temporal bone specimens is likely to impair the metabolic processes that support hearing transduction. Because hearing loss is often not the sole feature of this syndrome—vertigo, tinnitus, and a sense of aural fullness often occur as well—and because the symptoms respond frequently to immunosuppression, immune-mediated inner ear disease (IMIED) is the preferred term for this disorder when symptoms and signs are confined entirely to the ear. Devastating disabilities including profound deafness and severe vestibular dysfunction are potential sequelae of IMIED. Yet, if diagnosed promptly, IMIED is amenable to treatment. Unfortunately, the prognosis is difficult to gauge except in the setting of profound, sustained SNHL, in which case significant recovery of hearing is unlikely.
Anatomy of the temporal bone and audiovestibular apparatus. AN, auditory nerve; C, cochlea; ES, endolymphatic sac; OC, ossicular chain; SCC, semicircular canals; V, vestibule. (© 2000 John H. Stone, Md, MPH.)
Several characteristics distinguish IMIED from other syndromes of inner ear dysfunction. First, its time course is relatively rapid. IMIED is analogous to rapidly progressive glomerulonephritis in that inner ear inflammation progresses to severe, irreversible damage within 3 months of onset (and often much more quickly). With IMIED, in fact, the complete loss of hearing within a week or two of symptom onset is not unusual. Second, IMIED is usually bilateral to some degree, albeit the left and right sides may be affected asymmetrically and asynchronously. Typically, weeks or months separate involvement of the two sides, but the interval may be as long as a year or more. Finally, although some cases of IMIED are marked by precipitous, irretrievable losses of ...