Sensorineural hearing loss is a type of hearing loss that occurs when the auditory nerve of the inner ear structures is damaged. It is responsible for more than ninety percent of all hearing loss cases.
Sensorineural hearing loss often involves two types of hearing loss; sensory hearing loss and neural hearing loss.
Sensory hearing loss is a hearing loss that happens when the cochlea’s tiny hair cells in the inner ear are damaged.
On the other hand, neural hearing loss occurs when the hearing (auditory) nerve or the part of the brain responsible for hearing is damaged.
It is often very difficult to determine if the hearing loss is sensory or neural related or if the problem is a result of damage to both. Because of the difficulty in identifying the exact area affected, any hearing loss that stems from these two organs is termed sensorineural hearing loss.
Let's briefly examine the role the hair cells play in hearing and how damage to them can cause sensorineural hearing loss.
The Role of Hair Cells
The human ear is divided into three sections; the outer ear, the middle ear, and the inner ear. There is an organ known as the cochlea in the inner ear, which contains microscopic hair cells known as stereocilia.
The stereocilia are responsible for the conversion of vibrations in sound waves into neural signals that are transported to the brain through the auditory nerve. The brain interprets this signal as a sound and relays it back to the ear.
These inner ear hair cells that play a vital role in your hearing can get damaged by exposure to loud noise. Exposure to sounds or noise louder than 85 decibels (the equivalent of heavy traffic noise heard inside a car) can permanently damage the hair cells. This type of damage often results in severe hearing loss.
In most cases, you will not experience sensorineural hearing loss until about thirty to fifty percent of the hair cells in your inner ear have been damaged. Once they are damaged, hair cells cannot be repaired or replaced. This means that your hearing loss will be permanent.
Sensorineural hearing loss often starts with difficulty understanding high frequency or high pitched sounds, but as more damage occurs, hearing in the lower frequency may become worse.
Types of Sensorineural Hearing Loss
There are three types of sensorineural hearing loss; bilateral sensorineural hearing loss, unilateral sensorineural hearing loss, and asymmetrical sensorineural hearing loss.
Sensorineural hearing loss is said to be bilateral if it affects both ears. This is often caused by diseases like measles and exposure to loud sounds.
Unilateral sensorineural loss can be caused by Meniere's disease or tumor, affecting only one ear.
Sensorineural hearing loss is said to be asymmetrical when the hearing loss occurs in both ears, but the hearing loss is worse in one ear.
Sensorineural Hearing Loss Symptoms
Sensorineural hearing loss can come suddenly or can develop gradually. In cases where the hearing loss is gradual, you may not notice the symptoms immediately. Symptoms are often noticed when the sensory neural hearing loss is sudden. Most people experience the symptoms after waking up.
Below are some common symptoms of sensorineural hearing loss.
Difficulty hearing sounds in the presence of background noise: This is one of the telltale signs of sensory neural hearing loss. Due to the damage of the hair cells in your inner ear, your ear will find it difficult to pick sound signals in the presence of background noise.
Dizziness or balance problems: This is often caused by damage to the hair cells in the inner ear. Asides from being responsible for hearing, the hair cells are also responsible for the balance. Since the hair cells are damaged, you may experience dizziness or have difficulty maintaining your balance.
Difficulty hearing high-pitched sounds: At the initial stage of sensorineural hearing loss, you may experience difficulty hearing sounds that are high-pitched. If the hearing loss is not giving prompt medical attention over time, you may experience difficulty hearing low-pitched sounds. You will also notice difficulty in hearing or comprehending female and children's voices.
Muffled sounds: Due to the damage of the hair cells in the ear, the sounds and voices you hear may be muffled. This means that you will be able to hear sounds but will experience difficulty understanding what is being said. This increases the difficulty in comprehending speech or taking part in conversations. It may also lead to constant requests for repetition.
- Tinnitus or ringing in the ear is a common symptom of sensorineural hearing loss: The noise can be a ringing, clicking, whooshing, or humming sound in the ear. The pitch and frequency of the noise may vary.
To be able to adequately answer the question of whether sensorineural hearing loss gets worse, we need to identify the causes of sensorineural hearing loss. This will enable us to ascertain what causes have permanent effects and those with temporary effects.
Sensorineural Hearing Loss Causes
1. Exposure to Loud Noise
As stated earlier, extended or sudden exposure to loud noise can damage the hair cells in your ear and cause sensorineural hearing loss. Most people think that until they have been exposed to loud noise over an extended time, no damage is done to their hair, but this is not true.
Sudden exposure to loud noise, for instance, a bomb blast, can instantly damage your ears. Depending on the amount of damage done to the ear, the hearing loss can be temporary or permanent. Sensorineural hearing loss that is caused by sudden exposure to loud noise often affects only one ear.
Occupational noises, noise from recreational activities like snowmobiling, noise in musical activities like concerts and clubs, or constant use of headphones at high volumes for an extended period can all cause sensorineural hearing loss.
2. Chemotherapy and Radiation
Chemotherapy and radiation can damage the hair cells in the inner ear. Chemotherapy that involves the use of platinum drugs or compounds is known for causing sensorineural hearing loss.
Hearing loss occurs when the drug is absorbed into the fluid that surrounds the hair cells. The absorption of the drug causes damage to the hair cells and prevents them from functioning properly.
Just like chemotherapy, radiation can also damage the hair cells in the ear. But the damage is not just restricted to the hair cells in the ear. Radiation can also damage the part of the brain that is responsible for the interpreting of sounds. The auditory nerve that transmits signals from the hair cells to the brain can also be damaged by radiation, resulting in sensorineural hearing loss.
Presbycusis refers to age-related hearing loss. It is a major cause of sensorineural hearing loss, especially among senior citizens.
As you get older, your hearing becomes weaker. The weakening of your hearing results from the degeneration of the structure of the inner ear over time or a cumulative effect of the loud noise you have been exposed to overtime. Sensorineural hearing loss caused by age cannot be reversed.
4. Congenital Causes
Congenital causes of sensorineural hearing loss are factors that cause hearing loss in babies from birth. Sensorineural hearing loss is one of the most common hearing birth abnormalities. About 50% of children born with hearing loss got it from genetic factors, while others develop it from environmental factors.
Aside from genetic factors, if a woman suffers certain illnesses or diseases such as maternal diabetes, the baby’s hearing in the womb can be affected. Also, lack of oxygen at birth can cause sensorineural hearing loss.
In most cases, sensorineural hearing loss caused by congenital factors is permanent. However, the child can be assisted to hear with the use of hearing aids if the damage done to the ear is not so bad.
5. Other Causes
Other known causes of sensorineural hearing loss are head trauma, damage to the auditory nerve during surgery, acoustic neuroma, Meniere’s disease, the use of ototoxic medications, autoimmune inner ear disease, and certain infections like measles mumps, and meningitis.
Does Sensorineural Hearing Loss Get Worse?
The severity of sensorineural hearing loss is often determined by the degree of damage done to the ear. While the duration or the worsening of the hearing loss is determined by the underlying cause and the timing of medical attention.
For instance, if the sensorineural hearing loss is caused by an ear infection or an autoimmune inner ear disease, and the disease is given prompt medical attention, the effect of the disease on the ear may be minimal because all the hair cells have not been damaged.
Remember, hearing is still possible if not more than 30% of hair cells have been damaged. If, however, medical attention is delayed, the effects on hearing may be severe.
In this case, as the infection or disease spreads, the symptoms or severity of the hearing loss will also increase. You can go from having just ringing in your ear or dizziness to having random bouts of deafness to total or permanent deafness.
Sensorineural hearing loss caused by genetic or age-related factors is progressive. This means that with time, the hearing loss can worsen. For instance, sensorineural hearing loss caused by old age is a result of the wearing out of the hair cells in the inner ear. This degeneration of the hair cells is caused by age.
There is no way to reverse the degeneration because your ears cannot produce new hair cells. What this means is that the more the hair cells degenerate, the more severe the symptoms of the sensorineural hearing loss, and in most cases, it ends in total deafness.
On the other hand, if the hearing loss is caused by sudden exposure to loud noise or certain environmental factors, the avoidance of activities that expose you to the loud noise can help relieve symptoms and avoid further damage.
In some cases, sensorineural hearing loss caused by exposure to loud noise can be temporary because the hair cells are flattened by the loud noise and not necessarily damaged. If you stay away from the source of the loud noise for a while, your hearing will be restored.
If there is continued exposure to the loud noise, the hair cells will not just be flattened; they will also be permanently damaged, which will leave you with permanent hearing loss. You may experience a little relief from the symptoms after the fluid around the hair cells returns to normal.
If the hearing loss is caused by a tumor or a swelling putting pressure on the auditory nerve, the removal of the tumor can relieve the hearing loss symptoms. But in most cases, it is progressive; this means that your hearing can keep getting worse long after the tumor or swelling has been removed. In this case, the worsening of the symptoms will ultimately result in permanent hearing loss.
The importance of getting prompt medical help whenever you notice anything wrong with your ears cannot be overemphasized. If your sensorineural hearing loss is worsening, you often ignore the symptoms at the early stage. Do not try to self-medicate at home. Always seek professional medical help.
Have you or your loved one experienced sensorineural hearing loss? Did it get worse or better? We would love to hear about your experience.