Autoimmune hearing loss (AHL) is a form of sensorineural hearing impairment caused by the body’s own immune system mistakenly attacking structures within the inner ear. The hearing loss typically presents as a progressive decline, often affecting both ears, and can sometimes begin suddenly. AHL is often responsive to medical treatment if diagnosed early.
Autoimmune Inner Ear Disease
Autoimmune Inner Ear Disease (AIED) is a specific syndrome where the inner ear is the primary target of the immune attack. AIED is characterized by a rapidly progressive decline in hearing that typically occurs over a period of weeks to months. The hearing loss frequently fluctuates in severity during its progression and often involves both ears, although it may start in one ear before affecting the second.
Approximately half of all patients with AIED experience vestibular symptoms, such as dizziness, imbalance, or true vertigo. Tinnitus, or ringing, is also a common complaint, along with a feeling of aural fullness in the affected ear. While AIED can occur in isolation, in up to 30% of cases, it is a secondary manifestation of a larger, systemic autoimmune disease. AIED is often considered a diagnosis of exclusion, meaning doctors must first rule out other known causes before confirming the autoimmune nature of the condition.
Systemic Autoimmune Conditions That Affect Hearing
Systemic autoimmune diseases that involve widespread inflammation throughout the body can cause hearing loss as a secondary effect. These conditions damage the auditory system as part of a broader attack on connective tissue or blood vessels.
Cogan’s Syndrome is a systemic example characterized by inflammation of both the inner ear and the eyes, specifically causing non-syphilitic interstitial keratitis. This condition results in rapidly progressive or sudden hearing loss, often accompanied by severe vertigo, and can lead to profound deafness if not treated quickly.
Systemic Lupus Erythematosus (SLE), or lupus, is a condition where hearing loss can manifest as a complication. The hearing loss in lupus is thought to be a result of immune complex deposition and inflammation affecting the small blood vessels that supply the cochlea. Estimates suggest that up to 25% of individuals with SLE may experience some form of auditory symptom, which can include hearing loss, tinnitus, or balance problems.
Granulomatosis with Polyangiitis (GPA), formerly known as Wegener’s granulomatosis, is a form of vasculitis that involves inflammation of the blood vessel walls. When GPA affects the ear, it can cause sensorineural hearing loss by restricting the blood flow to the delicate structures of the cochlea. This inflammatory vasculitis can quickly lead to tissue damage and subsequent loss of hearing.
How the Immune System Damages Hearing Structures
The immune system causes hearing loss through a misdirected immune response against inner ear components. This damage often begins when the body produces autoantibodies or self-reactive T-cells that mistakenly recognize inner ear proteins as foreign invaders. One example of a potential target is the protein cochlin, which is found in the inner ear and becomes the focus of the immune attack. This errant response triggers a localized inflammatory cascade within the confined space of the labyrinth.
The inflammation can manifest as vasculitis, where the small blood vessels supplying oxygen and nutrients to the cochlea become inflamed and narrowed. Restricting blood flow to the stria vascularis, which is responsible for generating the electrical potential necessary for hearing, leads to functional disruption. Immune cells can also directly attack the sensory hair cells within the cochlea, which are responsible for converting sound waves into electrical signals.
Diagnosis and Management Strategies
Diagnosing autoimmune hearing loss begins with a detailed audiological evaluation to confirm the type and pattern of the sensorineural hearing loss. The diagnostic workup includes specialized blood tests to look for general markers of inflammation, such as an elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP). Testing also includes checking for specific autoantibodies, like antinuclear antibodies (ANA) or anti-neutrophil cytoplasmic antibodies (ANCA), which may suggest a coexisting systemic autoimmune condition.
Ultimately, a definitive diagnosis of AIED is often made clinically, based on the characteristic history of rapidly progressive, fluctuating hearing loss and a positive response to immunosuppressive therapy.
Management of AHL is focused on suppressing the immune system to halt the destructive inflammatory process. High-dose oral corticosteroids, such as prednisone, are the first line of defense and are administered aggressively to achieve rapid immune suppression. Early initiation of this therapy is paramount, as delayed treatment can lead to permanent and irreversible hearing loss.
For individuals who do not respond adequately to the initial course of oral corticosteroids, or those who cannot tolerate the side effects, other immunosuppressive or immunomodulating drugs may be used. These second-line treatments can include agents like methotrexate or other biological therapies. Intratympanic steroid injections, where the medication is delivered directly into the middle ear space, offer an alternative strategy to provide high local drug concentrations with fewer systemic side effects.