Types of Hearing Loss continued...
Sensorineural hearing loss most commonly results from damage to the hair cells in the inner ear. Other potential causes include damage to the 8th nerve (the nerve for hearing) or the brain. This type of hearing loss is often caused by age-related changes to the nerves and sensory cells of the inner ear.
Mixed hearing loss is a combination of conductive and sensorineural hearing loss, meaning that there may be a problem in the outer or middle ear, as well as in the inner ear (cochlea) or auditory nerve. Mixed hearing loss can be caused by a head injury, chronic infection, or an inherited disorder.
Hearing loss can affect one or both ears. It can occur suddenly (acute) or gradually get worse over time. If you experience a sudden hearing loss, you should see an ear, nose, and throat specialist as soon as possible.
Severe Hearing Loss Causes
In normal hearing, sound waves enter your outer ear. They travel through your inner ear to a shell-shaped tube called the cochlea, which is filled with fluid. As the fluid moves, it sets in motion thousands of tiny hairs which convert the sound vibrations into nerve impulses. Those impulses are then sent to your brain where they are processed into sounds you can recognize.
Hearing loss occurs when there is a problem with the structures of the ear that process sound. Any of these conditions can lead to severe hearing loss:
- Age. As people get older, the structures in the ear become less elastic. The tiny hairs get damaged and are less able to respond to sound waves. Hearing loss can progress over the course of several years.
- Loud noise. Exposure to loud noises -- for example, from power tools, airplanes, firearms, or from listening to loud music on a personal listening device -- can damage the hair cells in the cochlea. Hearing impairment severity depends on the loudness of the sound and the length of the exposure.
- Ear infections. During an ear infection, fluid can build up in the middle ear. Usually the hearing loss from an ear infection is mild and temporary. However, if ear infections aren't treated, they can lead to more serious long-term problems.
Perforated eardrum. An ear infection, loud sounds, head trauma, or intense pressure in the ear from flying in an airplane or scuba diving can rupture the ear drum, the membrane separating the ear canal and the middle ear, leaving a hole that may or may not heal. Depending on the size of the perforation, there may be a mild or moderate hearing loss.
- Illnesses or infections. Measles, mumps, meningitis, and Meniere's disease are just a few of the conditions that can cause hearing loss.
- Tumors. Both cancerous and noncancerous tumors can cause severe hearing loss. This includes acoustic neuroma (vestibular schwannoma) and meningioma. People who have a tumor might also experience numbness or weakness of the face and ringing in the ear.
- A foreign object in the ear. When objects get stuck in the ear, they can block hearing. Earwax -- the thick, sticky substance that normally prevents bacteria and other foreign substances from entering the ear -- can sometimes build up and harden in the ear, decreasing the ability to hear.
- Malformed ear. Some people are born with poorly formed ear structures, which prevent them from hearing well.
- Trauma. Injuries such as a skull fracture or a punctured eardrum can cause severe hearing loss.
- Medications. Some types of drugs, including the aminoglycoside class of antibiotics (streptomycin, neomycin, kanamycin), large quantities of aspirin, chemotherapy drugs (cisplatin, carboplatin), Vicodin (in large quantities), macrolide antibiotics (erythromycin) can cause hearing loss. Sometimes these effects are temporary and hearing will return once you stop taking the drug, but in most cases the hearing loss is permanent.
- Genes. Scientists have identified certain genes that make people more susceptible to severe hearing loss, particularly age-related hearing loss. Genetic hearing loss often begins with hearing loss diagnosed at birth.