Hearing Loss from Cancer Treatment

Posted on Aug 8, 2008 in Cancer

Paul Gidley, M.D. (Cancerwise.org)

Cancer patients experience many common side effects of chemotherapy and radiation therapy, but many people may be unaware that hearing loss is one of them, and it can affect some patients even years after treatment.

Answering questions about hearing loss caused by cancer treatment is Paul Gidley, M.D., associate professor in M. D. Anderson’s Department of Head and Neck Surgery. Gidley’s subspecialty is otology and neurotology, the study of the ear and the nerves for hearing, balance and facial function.

How does cancer treatment cause hearing loss?

Toxicities from chemotherapy and radiation can cause nerve damage that leads to hearing loss. This is called ototoxicity.

How does hearing work?

Sound vibrates the eardrum. These vibrations are transmitted by the middle-ear bones to the fluid within the inner ear (cochlea). The movements of the inner-ear fluids stimulate nerve cells within the inner ear. Those nerve impulses send messages to the brain, allowing people to hear sound.

What are the symptoms of hearing loss?

In general, any type of problem related to hearing can be a symptom of hearing loss, including ringing in the ears and difficulty understanding speech. Dizziness also may occur with hearing loss. In many patients, symptoms come and go or take years to develop. Patients may have a hard time identifying symptoms.

Patients have described symptoms by telling me:

* “I’m bothered by background noise.”
* “I have trouble hearing while on the phone.”
* “People seem to mumble or talk too fast.”
* “She/he has the television too loud.”
* “I need people to repeat words to me.”
* “I have a ringing sound in my ear.”
* “Sounds are painful to me.”

What’s the next step if there are symptoms?

Cancer patients who have any trouble hearing need to see an ear, nose and throat specialist and get a hearing test.

An ENT specialist can examine the structure of the inner ear and also see if there’s anything blocking the ear like wax. An audiologist can give patients a hearing test.

We evaluate those results based on a scale of hearing impairment that ranges from normal hearing to profound hearing loss.

Are there different types of hearing loss?

There are three types:

Conductive – People with conductive hearing loss have a problem with the sound-conducting mechanism of the ear. The problem involves the ear canal, eardrum and middle-ear bones.

Conductive hearing loss can be caused by:

* Wax in the ear canal
* A hole in the eardrum
* A middle-ear infection

This type of hearing loss can be corrected or reversed with surgery or medications.

Sensorineural – People with sensorineural hearing loss have a problem that involves the inner ear or the auditory nerve. The nerve carries electrical signals produced by sound from the inner ear to the brain.

Sensorineural hearing loss can be caused by:

* Ototoxicity from:
o Chemotherapy
o Radiation therapy
o Some antibiotics (long-term use)
* Diseases such as:
o Multiple sclerosis
o Syphilis
o Diabetes mellitus
* Trauma
* Heredity
* Noise

Treatment can include hearing aids or cochlear implants.

Mixed – People with mixed hearing loss have a combination of conductive and sensorineural hearing loss.

How many people have hearing loss?

In the general population, aging is one factor that leads to hearing loss, so a person’s chances of having hearing loss increase with age. Exposure to loud noise, either from the workplace or recreation, can cause hearing loss.

Hearing loss in the United States affects:

* 25% of the population over 65 years old
* 40% of the population over 75 years old

There are currently no statistics for the number of cancer patients who experience treatment-related hearing loss, but it’s not uncommon.

Is research being done to reduce hearing loss?

Ototoxicity represents an active area of research right now. Cancer researchers are looking at agents that might prevent hearing loss but won’t inhibit the anti-tumor effects of the cancer treatment.

We’re also looking at antibiotics that might help reverse ototoxicity, and there’s research being done to develop chemotherapy drugs that won’t cause hearing loss. There’s interesting research that involves use of stem cells to repopulate the inner ear cells to try to restore hearing, but this is not yet being tried in humans.