Hearing loss can be separated into three main types. Sensorineural hearing loss comes from the inner ear and its pathways to the brain. Conductive hearing loss is related to poor sound transmission. Sounds do not get to the inner ear in an efficient way. Finally, there is a mixed type of hearing loss that has components of both. Conductive hearing loss is usually the easier of the three to correct with some sort of medical or surgical intervention. In order to effectively treat conductive hearing loss, it’s important to understand the structure of the ear and the possible causes of conductive hearing loss to determine the best method of correction.
Anatomy of the Ear
The outer ear consists of the pinna, the skin-covered cartilage that makes up the curve of the ear, and the earlobe. The inner ear contains the auditory ossicles, three small bones called the malleus (hammer), incus (anvil) and stapes (stirrup), as well as the eardrum, tympanic cavity and the eustachian tube. The inner ear is made up of the bony labyrinth, the cochlea and the vestibular system. Sound enters through the outer ear, which funnels it into the middle ear, where those tiny bones vibrate. The vibrations travel to the cochlea, which turns the sound into nerve impulses in the brain. The bony labyrinth attaches the nerves in the inner ear to the cochlea. They are filled with fluid and send balance information to the brain. The eustachian tube drains fluid from the middle ear down the throat.
About Conductive Hearing Loss
Conductive hearing losses can be transient, or short-lived. The reason for the hearing loss will play into how often it occurs and how easy or difficult it is to treat. Malformations, for example, are rare, while fluid in the inner ear is common. There are many reasons a person might experience conductive hearing loss. Here are 10 possible causes.
- Earwax - The ear produces wax to moisturize the ear canal. This wax helps fight possible infection and keeps dirt and other particles from the middle and inner ear. When wax builds up, people try to remove it by using a cotton swab, but that just impacts the wax deeper in the ear. This is easy to correct. An ENT doctor can simply remove the impacted earwax.
- Fluid in the ear - Even if the ear is not infected, fluid in the middle ear or inner ear can make it hard to hear. This happens a lot in children because their eustachian tubes are not completely formed.
- Ear infections - The middle ear can become infected because of a cold or allergy, or because of “swimmer’s ear.” It fills up with fluid and causes hearing loss. Ear infections can be treated at home, but moderate to severe cases may require an antibiotic or prescribed ear drops.
- Foreign body in the ear - As many parents know, children are prone to sticking small objects in their ears, which causes obstruction. Bugs can also fly in the ears. An ENT doctor will simply remove the obstruction, providing quick relief.
- Cholesteatoma - A benign growth in the middle ear, this condition occurs when a growth of cells get trapped in the middle ear space. This condition usually occurs as a complication of chronic ear infection or chronic eustachian tube dysfunction.
- Perforated eardrum - The eardrum can be perforated because of trauma, or if an ear infection goes untreated the trapped fluid can cause a hole in the eardrum. This condition usually heals on its own, but the doctor can close the perforation if necessary.
- Other trauma - Other damage to the middle ear bones, including trauma, can cause conductive hearing loss. Long standing fluid that can’t drain can also eat away at the bony tissue of the middle ear bones and impair hearing. This damage can be treated a number of ways.
- Eustachian tube malfunction - This condition causes fluid buildup, especially in children. Because of a child’s smaller size, a child’s eustachian tubes are also smaller and tend to be more horizontal, which makes it harder for the eustachian tubes to drain. Adults have a slant to their eustachian tube, so malfunction isn’t quite as common, but can still occur.
- Ossicular fixation - Over time, the middle ear bones can calcify, impeding ear bone motion. The stimulation of the inner ear is poor, causing a problem with sound transmission. Otosclerosis, a genetic condition, can cause calcification and usually presents in adulthood. It is more common in women, and is seen often during pregnancy. This condition can be treated with a hearing aid, or with a procedure called a stapedectomy.
- Malformation - Malformation can occur when ear structures fail to develop properly. There may be no outer ear, no pinna or auricle, or malformation in the ear canal. This may be considered more difficult to correct, and often requires an invasive surgical procedure.
To assess the type of hearing loss a patient is experiencing, your audiologist will conduct a hearing test to determine if the loss is conductive, sensorineural, or a combination. Once the type of hearing loss is identified, the proper treatment can be planned with your ENT physician.