See Related: Ear Infections
Hearing loss has a lot of different causes and manifestations. It can be sudden or gradual. It can occur in one ear or both ears. It can be temporary or permanent. It happens to people of all ages. Before discussing causes and treatments for hearing loss, it is important to understand how hearing works.
How We Hear
There are three sections of the ear: the outer ear, middle ear and inner ear. Each section helps move sound through the process of hearing. When a sound occurs, the outer ear feeds it through the ear canal to the eardrum. The noise causes the eardrum to vibrate. This, in turn, causes three little bones inside the middle ear (malleus, incus, stapes) to move. That movement travels into the inner ear (cochlea), where it makes tiny little hairs move in a fluid. These hairs convert the movement to auditory signals, which are then transmitted to the brain to register the sound.
Causes of Hearing Loss
Hearing loss occurs when sound is blocked in any of the three areas of the ear. The most common cause of hearing loss in children is fluid behind the eardrum (more likely when they are less than 3 years old and/or when they have a "cold"), followed by an ear infections, congenital hearing loss (born with it), and finally ear wax blocking the ear canal.
- In the Outer Ear: Earwax build-up, infections that cause swelling, a growth in the ear canal, injury or birth defects can restrict hearing in the outer ear.
- In the Middle Ear: Fluid build-up is responsible for the most common infections and blockages in the middle ear. Fluid in the middle ear prevents the bones from processing sounds properly.
- In the Inner Ear: Congenital malformations of the temporal bone in children can result in hearing loss - this basically means that the inner ear did not form correctly in utero. There can also be genetic causes of hearing loss - there are many DNA genes that contribute to the hearing mechanism - if one or more of these genes are abnormal then hearing can be affected.
Other causes of hearing loss include:
- Heredity and Genetic Causes: There is a wide variety of diseases and syndromes that are either genetic or hereditary that can cause hearing loss. Some, like rubella (German measles) occur when a pregnant mother has the disease, which causes hearing loss in the baby. Other, rarer types of hereditary and genetic causes include CHARGE Syndrome, Connexin 26 disorder, Goldenhar Syndrome,Treacher Collins Syndrome, Usher Syndrome, Waardenburg Syndrome and otosclerosis (growth of spongy bone tissue in the middle ear).
Most causes of outer ear hearing loss can be remedied. But problems of the middle and inner ear can lead to permanent hearing loss, which is why it is important to seek medical attention quickly if you are experiencing a problem hearing.
Types of Hearing Loss
There are five types of hearing loss:
- Conductive hearing loss: Caused by conditions that block the transmission of sound through the outer ear and eardrum to the middle ear.
- Sensorineural hearing loss: Inner ear damage that occurs as part of the natural process of aging.
- Mixed hearing loss: Mixed hearing loss refers to people who have both conductive and sensorineural hearing loss. Most people experience more than one type of hearing loss.
- Central hearing loss: This occurs when the central nervous system fails to send a readable signal to the brain, which is called a central auditory processing disorder. People with central hearing loss generally can hear all sounds, but cannot separate or process them.
Hearing loss is measured in four degrees: mild, moderate, severe or profound. The degree of hearing loss drives the selection of the best form of treatment on a case-by-case basis.
Hearing Loss Treatments
The location, type and degree of hearing loss impact the choice of treatments for any hearing problem. The most common treatment options include:
- Antibiotics, decongestants and pain medication to overcome ear infections.
- Myringotomy, a piercing of the eardrum to allow for fluids to drain out of the outer ear.
- Insertion of a tube into the Eustachian tube (part of the anatomy that connects the middle ear to the back of the throat) to keep it open and allow for normal fluid drainage. This technique may be recommended for people who get frequent ear infections.
- Hearing aids.
- Surgery like cochlear implantation in cases of profound hearing loss of both ears.