Sensorineural hearing loss is the most common kind of hearing loss. Basically it means the little hairs inside the cochlea have become damaged or have died. This means they can no longer be activated by sound vibrations channelled through the outer and middle ear and they cannot, therefore, change the vibration into an electrical impulse. The hearing loss can range from mild to profound. It usually affects both ears and is most often progressive. The time of onset and the rate of progression differs greatly between individuals. There is no cure and the condition is irreversible. About 80% people with this kind of deafness experience tinnitus.
For those over 50, one in four will have a hearing loss of some degree or other. When we get to 75 this becomes three in four. This kind of hearing loss, or age related hearing loss is almost always sensorineural.
Medical science has still not found a cause. It may be genetic or hereditary; it may be caused be exposure to loud noise (industrial deafness) or by a childhood illness such as measles or mumps, or a women catching Rubella (German measles) while pregnant and passing the condition to her child. Otosclerosis and ototoxic drugs can also cause sensorineural deafness.
Sensorineural deafness can be sudden. A person can go from hearing to totally deaf within hours. However, more often there is a gradual onset of deafness which takes place over months or even years. This is seen particularly in the aging population where their deafness encroaches slowly as they age – the longer they live the deafer they become. In my case it took about 20 years from having measles at age 9 to being deaf by the time I was 35.
There is no treatment for the cause of sensorineural deafness so only symptoms can be treated. The first thing is a hearing aid which will help with hearing in the mild to moderate hearing loss categories. However, once hearing loss progresses to severe and profound, no matter how loud sound is amplified there are no hair cells in the cochlea to change the sound vibrations into electric signals. So it won’t matter how loud the sound is the person wearing the hearing aid will never be able to hear it. It’s a bit like putting glasses on a blind man – doesn’t matter how thick or strong they are he will never be able to see.
At first deafness is mild, which will cause some minor communication problems and a hearing aid should help. As the sensorineural hearing loss progresses stronger hearing aids will be prescribed. If the condition continues then eventually hearing aids will not work at all. The only solution then is a Cochlear Implant.
The Cochlear implant has been the most successful for people who have a sensorineural hearing loss. Unlike a hearing aid a Cochlear Implant does not amplify sound. Rather the external speech processor converts the sound into an electrical impulse which is then directed straight to the hearing nerve in the cochlea. It by-passes the damaged cochlea hair cells stimulating the hearing nerve via the electrodes implanted in the cochlea. From then on the normal hearing process takes over, the electrical signal is sent along the hearing nerve to the brain where the person interprets it as sound.