Autoimmune diseases occur when your body’s immune system mistakenly attacks healthy tissue, thinking it’s harmful foreign pathogens. Autoimmune hearing loss, known as Autoimmune Inner Ear Disease (AIED), is sensorineural hearing loss. This means that AIED is tied to inner ear damage, often causing problems within the pathways connecting your inner ear and your brain.
In short, patients with AIED will experience their immune system attacking specialized cells in their inner ear and causing hearing loss. Before we get into that, though, let's take a look at what hearing loss is.
Hearing Loss As a Disability
Hearing loss is one of the most widespread disabilities affecting the current population. One of the main reasons for this phenomenon is that we are constantly using our hearing organs as humans.
This constant use makes every person susceptible to even the mildest form of hearing loss that comes with age. However, there are multiple types of hearing loss. While it is more common for the elderly to develop hearing loss, age is not the only factor that affects the onset of this condition. To understand this better, let's look at what types of hearing loss a person can experience and how autoimmune disorders can affect these categories.
Types of Hearing Loss
Hearing loss can be thought of as the depreciation of our natural ability to recognize sound waves at certain threshold decibels. Breaking that down further, we can hear the world around us through our body’s ability to sense sound waves. Those sound waves are unique in their frequencies and reach our ears at different levels of force called decibels.
A decibel is a unit used to measure the force or loudness of a sound. As a person begins to lose their hearing, they begin to struggle with hearing certain frequencies at their natural decibel level. This level is called the decibel threshold.
A person with normal hearing and no decibel threshold deficits would hear both the sounds of loud motors passing by on the street and the soft chirping of a bird in a tree overhead. As a person loses their ability to hear, the decibel threshold for healing rises. So, while the Harley Davidson roaring past is still audible, the chirping of a bird has been lost as it is below the threshold.
Let's look at what exactly causes this threshold to rise and what kinds of hearing loss people face.
Conductive Hearing Loss
Conductive hearing loss is hearing impairment due to any issue where the conduction of a sound wave to the hearing organs is blocked. Because sound travels in energy waves, these frequencies can be blocked from reaching the middle and inner ear, which means they won’t be recognized by our sensing organ.
Conductive hearing loss can be as mild as ear wax build-up, or it can pose serious threats, like foreign objects lodged within the ear canal due to traumatic injury. Typically, this kind of hearing loss is correctable. It can result from damage to the eardrum or the bones behind the eardrum which transmits sound to the inner ear.
Autoimmune conditions that affect your ears can lead to conductive hearing loss. When your body mistargets its cells, this can result in swelling or excretion that can cause hearing impairment. While this isn’t AIED, conductive hearing loss can be caused by autoimmune disorders in general.
Sensorineural Hearing Loss
This form of hearing loss deals specifically with the neurological aspect of the hearing process. As you know, sensorineural hearing loss relates to your inner ear and the pathways between your inner ear and the brain.
Sensorineural hearing loss can be more severe and has multiple causes, from traumatic injury to birth defects to genetics.
Compartments of the Ear
Your ears are composed of three unique parts, the outer ear, the middle ear, and the inner ear. All three compartments of the ear have specific roles along the hearing pathway.
The outer ear acts as a protective barrier for the ear canal, the port by which sound travels from the outside world into the ear.
The middle ear is divided from the outer ear by the tympanic membrane, better known as the eardrum. This structure acts as a barrier for the tympanic cavity—a space in the ear that houses three important small bones. These bones are the incus, malleus, and stapes. These three bones respond to the vibrations that come from the eardrum as sound waves travel down the ear canal to interact with it.
The inner ear is the last part of three compartments of the ear. This part of the ear houses the cochlea, which is the sensorineural component of the ear. These neurons take the vibrations from the three bones of the tympanic cavity and convert those vibrations into electrical impulses.
These impulses are then taken through the nervous system to the brain, where they are processed and understood as sound.
Autoimmune Disease and Hearing Loss
Autoimmune disease can affect any system in the body. Your immune system is designed to recognize foreign elements in your body called ‘pathogens’ and eliminate or remove them. But what exactly are pathogens?
A pathogen is a microorganism, whether it's a bacteria, virus, or some kind of microbe that specifically leads to a disease state. Giradia, for instance, is a pathogen that can be acquired through unfiltered drinking water that can cause intense gastrointestinal distress.
For the most part, we owe a lot of thanks to our immune system, as this vital part of our biology helps keep us alive. If it weren’t for an intricate system that policies our biological functions, we would be highly susceptible to disease states, and any pathogen we might run across could pose a serious problem for us.
When that same system mistakes natural, healthy cells for pathogenic invaders, we can start to experience some serious problems.
Autoimmune Inner Ear Disease (AIED)
As explained above, autoimmune inner ear disease is a specific kind of autoimmune disease that targets certain inner ear cells and causes your immune system to view them as foreign. This disease can occur on its own or be part of a wider spread autoimmune disorder.
AIED is also extremely rare. While hearing loss is one of the most common disabilities, less than one percent of people with hearing loss will experience AIED. Despite it being so rare, it has had very definable presentations in the people who have developed it.
Typically a person who has AIED will experience this disease with a sudden onset of hearing loss. This is called sensorineural hearing loss, or SNHL.
Not only does it develop quickly, but it typically develops unilaterally before eventually becoming bilateral. This means that the most common presentation of AIED will be sudden, unexplained loss of hearing in one ear over a short period of time, eventually followed by loss of hearing in the second ear as well.
This disease has proven hard to diagnose because it is similar in presentation to many others. The ability to recognize that the immune system is attacking healthy cells in the ear is difficult. One symptom that has been reported commonly with AIED is the presence of tinnitus.
Treatment for AIED
Studies are still being conducted to understand better how AIED attacks the inner ear and what kinds of treatment are most effective.
The fact that this disease affects the inner ear means that it directly impacts the neurological elements of your hearing organ. Studies have shown that patients with AIED have responded well to steroidal treatment; however, this is still in development.
Autoimmune disease can seem overwhelming and can pose multiple challenges. If you suspect that you may be suffering from AIED or an autoimmune-related disorder, seek immediate medical assistance.
"Above all, if you or one of your loved ones has hearing loss, there is hope. It is important to get evaluated by a health care professional. Hearing aid options with Audien are low-cost and effective for most situations." - Drew Sutton, MD, Board-Certified Otolaryngologist.
While medicine is still growing to understand what AIED is and how it can be treated, early diagnosis and treatment may help prevent permanent hearing loss. Treatment with corticosteroids and immunosuppressive treatments that help minimize the damage done by your immune system may help you avoid more significant or even permanent hearing loss.
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Types of Hearing Loss | asha.org