Autoimmune Inner Ear Disease: A Comprehensive Guide to Diagnosis and Management
Autoimmune inner ear disease is a complex condition that affects the inner ear, causing a range of symptoms such as hearing loss, tinnitus, vertigo, and dizziness. The condition occurs when the body's immune system mistakenly attacks the healthy cells and tissues of the inner ear, causing inflammation and damage.
To diagnose autoimmune inner ear disease, doctors rely on a combination of tests and clinical assessments. One of the primary tests is the detection of antibodies to certain proteins in the inner ear. These proteins are typically found in healthy cells and tissues, but in patients with autoimmune inner ear disease, the immune system produces antibodies against these proteins.
Human leukocyte antigens, ANA, and C-reactive protein are all good markers of autoimmune inner ear disease, and their detection in a patient's blood sample can indicate the presence of the condition.
However, it's important to note that the absence of these markers does not necessarily rule out autoimmune inner ear disease, and a doctor should consider other factors such as a patient's medical history and symptomatology to make an accurate diagnosis.
ANA test
ANA and autoimmune inner ear disease (AIED) are both characterized by hearing loss and tinnitus, two symptoms that are typical of this condition. The inner ear contains hair cells that help maintain balance and hearing.
This disease can affect the entire body, or just the inner ear, or involve both. This disease is more common in middle-aged women. However, in a small percentage of cases, ANA may occur without symptoms at all.
ANA and autoimmune inner ear disease have similar clinical features, but the latter can cause sensorineural hearing loss as well. These two diseases are not responsive to corticosteroids and have a genetic origin. In autoimmune otopathology, ANA is thought to be a result of an abnormality of CD4+ T cells.
However, not all auto-reactive T cells are eliminated by the thymus, which is very effective in the elimination of most antigens. Rather, autoimmune otopathology may be the result of an abnormality in other regulatory mechanisms in the body.
Although researchers have yet to prove the role of food allergy in AIED, they have determined that ANA is a cause of Meniere's disease. While researchers have been unable to prove a causal link between the two conditions, autoimmune inner ear disease is a common cause of hearing loss in patients with the disorder.
While it is not known what causes ANA and AIED, researchers believe that the two diseases share similar mechanisms. The immune system is complex and can cause damage to the inner ear.
Despite these similarities, the diagnosis of primary AIED remains a challenge because no specific serological biomarkers exist. Because of this, various groups have sought to identify autoantibodies against various components of the inner ear in patients suspected of having this condition.
One of the best-known methods is the 68-kD inner ear antigen and the antibody to the Heat Shock Protein 70. These antibodies are present in up to a third of AIED cases.
Rheumatoid factor
Autoimmune inner ear disease (AIED) is caused by an abnormal immune response to a foreign substance or insult.
These invaders can include viruses or pathogenic bacteria. These agents can infect the middle or inner ear and alter host molecules to become self-antigens. Injuries can expose the antigens to the immune system, causing permanent damage to the tissues.
Symptoms of AIED may include progressive two-sided hearing loss, dizziness, and tinnitus. The exact cause of this disease is unclear. The autoimmune disease tends to develop in clusters of two or three different diseases. However, in approximately 30% of patients with AIED, other autoimmune diseases are present. As a result, it can mimic symptoms of hearing loss or an ear infection.
T cells play a vital role in the development of autoimmune inner ear disease. T-cells from systemic circulation can penetrate the blood-labyrinthine barrier to enter the inner ear. They subsequently activate helper T lymphocytes against self-proteins and cause a damaging immune response to the inner ear. This inflammation ultimately destroys the sensory and supporting cells in the cochlea.
Research on autoimmune inner ear disease is a fertile field. The discoveries that arise from AIED have implications for other inner ear disorders as well. However, despite this, there are many challenges, including limited access to the inner ear, the inability to accurately diagnose the condition, and the tendency for patients to develop refractory hearing loss despite steroid treatment.
Biological therapies for autoimmune inner ear disease have shown promising results. TNF-a blockade is a type of biological therapy that inhibits the action of tumor necrosis factor (TNF), a proinflammatory cytokine. It also activates neutrophils and NK cells and increases vascular permeability. The drug was isolated in 1975 and has been tested in AIED patients.
Human leukocyte antigens
Although the causes of autoimmune inner ear disease are not well known, researchers have identified antibodies to sulfo glucuronosyl glycolipids. Researchers from Japan, Yamawaki M, found that patients with this condition often had antibodies to these lipids. Further, there are other possible reasons for the presence of these antibodies, such as autoimmune disorders. The bystander damage theory explains why some patients experience the attack/remission cycle of Meniere's disease.
If the symptoms of autoimmune inner ear disease are present, blood tests may be ordered. Detailed testing will reveal if the patient is suffering from an autoimmune disorder, such as rheumatoid arthritis, or another underlying disease. In some cases, the autoimmune disorder can also be a cause of hearing loss. A doctor may perform a blood test to determine whether the cause of dizziness is an autoimmune disorder or a cause of the symptom.
Interestingly, some researchers have proposed that the cause of Meniere's disease is a malfunction of the immune system. HLA-typing is relevant in the context of the patient's ethnic background, however. Studies on Korean subjects may not apply to individuals from other ethnic groups. Regardless, the research demonstrates that human leukocyte antigens are associated with certain types of autoimmune inner ear diseases.
Interestingly, the concept of autoimmunity was not widely accepted by the scientific community until the late fifties. However, researchers have emphasized that autoimmune inner ear disease is an autoimmune disorder, and the mechanism of the disease is similar to other autoimmune diseases. These diseases have similar symptoms, but they are mediated by different immune responses. A major component of the autoinflammatory response in AIED is autoreactive CD4+ T cells.
C-reactive protein
Autoimmune inner ear disease is a condition that affects the hair cells of the inner ear, which are essential for hearing and balance. Although some cases of the disease have fewer symptoms, many suffer from hearing loss. Because hair cells aren't redundant, the loss of hearing in autoimmune inner ear disease is often more pronounced. Here are some symptoms of AIED and how C-reactive protein may be a cause.
A major symptom of autoimmune inner ear disease is sudden, fluctuating hearing loss, which is usually classified as sensorineural and is often accompanied by vestibular symptoms. Blood tests may be ordered to confirm or rule out the possibility of autoimmune inner ear disease. Anti-cochlear antibody test, Lyme titer, and lymphocyte transformation assay may be performed. Various hearing tests, such as audiometry, otoacoustic emission testing, and electrocochleography, may be done as well.
The bystander-damage theory is an alternative explanation for the attack/remission cycle of Meniere's disease. Cytokines are present in the cochlea, and immune responses are commonly associated with inflammation. If C-reactive protein levels are elevated, the condition is considered autoimmune. In addition to circulating C-reactive protein, IgG4 is known to trigger an immune response.
When the TLR-4 gene is mutated, the immune response to acoustic injury is suppressed. However, when acoustic overstimulation is caused, the TLR-4 gene is upregulated. This may lead to a dysfunctional response in the inner ear. Once this happens, the condition is called autoimmune inner ear disease. However, it is important to note that this is not the only cause of autoimmune inner ear disease.
Enbrel
An autoimmune disease is an inflammatory condition in which the body attacks itself, causing inflammation. One possible cause is an allergy. The ear is a sensitive organ, and if you have an allergy to food, you may be at risk for developing autoimmune inner ear disease. Research has shown that food allergies can contribute to the disease, but its significance in treating AIED remains uncertain. But an allergy to one type of food is not necessarily indicative of autoimmune disease.
This condition is rare and difficult to treat, so there are few approved treatments. Research has shown that gamma globulin infusions can be effective in many autoimmune conditions, but they are also costly. There are no formal trials comparing Enbrel with other immunomodulating drugs, which suppress the immune response. Anti-TNF drugs and minocycline have not been tried in patients with autoimmune inner ear disease.
There are many potential causes of autoimmune inner ear disease, but a common one is immune cells attacking inner ear proteins. In a rare case of autoimmune inner ear disease, suppressing the immune response can help limit cochleitis and allow for partial hearing recovery. This requires a multidisciplinary approach and is usually associated with a combination of immunosuppressive medications. Other options include immunosuppressive therapy with steroids and immunomodulators, plasmapheresis, intravenous immunoglobulin, and intravenous immunoglobulin. Additionally, pregnant women must be closely monitored by a maternal-fetal medicine specialist to safely take the medication.
Enbrel is an immunotherapy that targets TNF-a, a major proinflammatory mediator in RA. This drug blocks TNF-a's biological activity, and as such, reduces joint inflammation. As with all immunotherapy, there are many side effects to Enbrel, including the possibility of an adverse side effect. The drug's use in patients with autoimmune inner ear disease is controversial.
Conclusion
Autoimmune inner ear disease is a complex condition that can cause a range of symptoms, including hearing loss, tinnitus, vertigo, and dizziness. The condition occurs when the body's immune system mistakenly attacks the healthy cells and tissues of the inner ear, causing inflammation and damage.
Although the exact cause of AIED is unclear, researchers have identified some potential markers, including ANA, human leukocyte antigens, C-reactive protein, and rheumatoid factor.
While there is no specific serological biomarker for primary AIED, various groups have sought to identify autoantibodies against various components of the inner ear in patients suspected of having this condition.
Although research on autoimmune inner ear disease is a fertile field, there are many challenges, including limited access to the inner ear, the inability to accurately diagnose the condition, and the tendency for patients to develop refractory hearing loss despite steroid treatment.
Biological therapies for autoimmune inner ear disease have shown promising results, including TNF-a blockade, a type of biological therapy that inhibits the action of tumor necrosis factor.
Sources
- Autoimmune Inner Ear Disease: Current Concepts and Challenges: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6511745/
- Autoimmune Inner Ear Disease: https://www.mayoclinic.org/diseases-conditions/autoimmune-inner-ear-disease/symptoms-causes/syc-20352378
- Enbrel: https://www.rxlist.com/enbrel-drug.htm