Download Sensorineural hearing loss - Do You Know Educational Series

It is easier to understand sensorineural hearing loss if you know more about how the ear works. The ear is
made up of 3 main parts: 1) the outer ear, 2) the middle ear, and 3) the inner ear. The outer ear extends from
the part of the ear you can touch to the ear drum. The outer ear acts like a funnel to direct sound to the ear
drum.
Ear Drum (Tympanic Membrane)
Outer Ear
Middle Ear
Inner Ear
The ear drum separates the outer ear and the middle ear. Behind the ear drum is the middle ear, which is
normally filled with air. Three tiny bones inside the middle ear are named for their shapes: the malleus
(hammer), the incus (anvil), and the stapes (stirrup). The 3 bones connect to form a chain. The first bone, the
malleus, is connected to the ear drum. The last bone, the stapes, is connected to another tiny membrane called
the oval window.
The oval window is the beginning of the inner ear, or cochlea. When sound hits the ear drum, the tiny bones
are set in motion, and the last one pushes on the oval window, activating the cochlea. Inside the cochlea there
are thousands of tiny nerve endings. These nerve endings are called hair cells and are surrounded by fluid.
The hair cells change the sound waves into electrical impulses that travel along the auditory (hearing) nerve to
the brain. The brain processes these impulses and changes the sounds into something meaningful to you.
Sensorineural hearing loss occurs when something damages the inner ear, the auditory (hearing) nerve, or the
parts of the brain that process sound. Sensorineural hearing loss includes 2 types of hearing loss: sensory
hearing loss and neural hearing loss. Sensory hearing loss occurs when the cochlea or the tiny hair cells are
damaged. Neural hearing loss occurs when damage occurs to the hearing nerve or the part of the brain
responsible for hearing. Sometimes it is hard to tell whether the problem is sensory, neural, or both. That is
This document is not intended to take the place of the care and attention of your personal physician or other professional medical services. Our
aim is to promote active participation in your care and treatment by providing information and education. Questions about individual health
concerns or specific treatment options should be discussed with your physician.
Copyright © 2003 St. Jude Children's Research Hospital
Revised 07/03
www.stjude.org
Page 1 of 2
why we often use the general term sensorineural hearing loss. Sensorineural hearing loss usually starts in the
high frequencies (high pitches). As more damage occurs, the hearing in the lower frequencies may become
worse.
Sensorineural hearing loss can have many different causes. Listed below are some of the most common
causes of sensorineural hearing loss for children at St. Jude Children’s Research Hospital.
Chemotherapy
The most common types of chemotherapy that cause hearing loss are the platinum drugs or compounds. You
may recognize the names of these drugs—cisplatin or carboplatin. When chemotherapy causes a hearing loss,
it is usually because the drug has been absorbed into the fluid that surrounds the hair cells. This causes
damage to the hair cells and keeps them from working properly. When this type of damage occurs, the hair
cells cannot send signals to the brain, making it harder to hear certain sounds.
Radiation
Radiation can cause sensorineural hearing loss in 2 different ways. Radiation may damage the hair cells, like
chemotherapy does. Radiation may also damage the area of the brain that changes sound into meaning or the
nerves that transmit electronic signals between the hair cells and the brain.
Surgery or tumors
The areas of the brain that process sound can be damaged during brain surgery. The auditory (hearing) nerve
can be bruised or even cut. Swelling (edema) or a tumor pressing on the nerve can keep the nerve from
working properly.
This kind of hearing loss can be either permanent or temporary, depending on what has caused the hearing
loss. The body cannot grow new hair cells. If the hair cells in the cochlea have been damaged, the hearing will
not return to normal, although sometimes the hearing will get a little better after the fluid around the hair cells
returns to normal. If the hearing loss has been caused by radiation, it will probably be permanent. Hearing can
improve if a tumor or swelling has been putting pressure on the auditory nerve and the pressure is relieved.
However, sometimes hearing can continue to get worse long after treatment has ended. This is called a
progressive hearing loss.
The first step is to have a hearing test to determine the type of hearing loss and how severe it is. The
audiologist and your child’s doctor will discuss possible interventions. Together, you will then be able to
develop the best plan for your child.
If you have questions about sensorineural hearing loss, call Rehabilitation Services at 595-3621. If you are
inside the hospital, dial 3621. If you are outside the Memphis area, call toll-free 1-866-2ST-JUDE (1-866278-5833), extension 3621.
This document is not intended to take the place of the care and attention of your personal physician or other professional medical services. Our
aim is to promote active participation in your care and treatment by providing information and education. Questions about individual health
concerns or specific treatment options should be discussed with your physician.
Copyright © 2003 St. Jude Children's Research Hospital
Revised 07/03
www.stjude.org
Page 2 of 2