Early Diagnosis, Treatment Are Key to Remedying Hearing Loss

Rush Limbaugh’s revelation that he is going deaf has resonated through a nation that has 28 million people who are hard of hearing or experience total hearing loss.

Doctors at the House Ear Clinic in Los Angeles diagnosed the controversial radio personality as having an autoimmune disorder that attacked his inner ear. About 1,000 people in the United States will experience sudden and unexplained deafness in both ears this year because of an autoimmune attack. The prognosis generally depends on how long it takes to receive a diagnosis and proper treatment.

At 50, Limbaugh, like many others, simply thought he was experiencing age-related hearing loss. He obtained a hearing aid for his left ear in June. But when his hearing worsened over the summer--and his right ear became affected--he sought the help of the California hearing clinic.

Autoimmune inner ear disease is a fairly rare cause of sudden hearing loss. More common explanations are viruses or blood clots, said Dr. Jeffrey Harris, chairman and professor of otolaryngology at UC San Diego.

Harris developed the antibody test for this specific autoimmune disorder. He said that people who test positive for the antibody--a marker for the immune system attack--have a good chance of recovering their hearing after a month of high-dose steroids. If caught early enough, generally before the second ear becomes involved, 70% of people with autoimmune hearing loss will improve.

No one knows what causes the immune system to attack the cells that line the cochlea, or inner ear.

“It’s very frightening when someone has their hearing slip away quickly, day by day,” said Dr. James Battey, director of the National Institute on Deafness and Other Communication Disorders.

Dr. Christopher Linstrom, associate professor of otolaryngology at New York Eye and Ear Infirmary in Manhattan, explains that the cells of the ear that are most vulnerable to immune attack are the cochlear hair cells. For some reason, the body stops recognizing parts of the inner ear as “self” and makes immune-fighting antibodies that damage the hair cells.

The cochlea’s function is to convert sound pressure waves into electrical impulses. Sound is measured in units of pressure and travels to the eardrum from the external auditory canal.

The eardrum transmits vibrations to three bones in the middle ear that amplify sound; the vibrations of the bones move fluid that sits inside the inner ear. The vibrating fluid and pressure transmit signals into the cochlea, where the hair cells are coiled around the auditory nerve.

The vibrations of the hair cells stimulate the auditory nerve, which is connected to the brain stem. The sound signals travel this route into the brain and are eventually transmitted to portions of the temporal lobe so that sound is recognized by the brain.

In Limbaugh’s case, as in others with autoimmune hearing loss, the part of the machinery that is broken is the cochlear hair cells. And that’s precisely why a cochlear implant is an ideal option for those who have significant hearing loss that doesn’t return following steroid treatment.

A cochlear implant acts like hair cells. The prosthesis contains a plastic coil with eight to 20 pairs of electrodes on it. When the ear captures sound, the electrical current passes through the electrodes and stimulates the nerve fibers. The message is sent to the brain.

For more information on hearing loss, go to the National Institute on Deafness and Other Communication Disorders at https://www.nidcd.nih.gov.