Deafness is sometimes mistakenly viewed as a total inability to hear anything at all. In fact, there is a vast range of different stages and levels of hearing loss. There is also a wide range of causes, starting from birth defects, through to head injuries and serious illnesses. Let's learn about cortical deafness.
If someone has impaired hearing, it is important to get the right diagnosis. This will ensure they get hearing aids and treatment that address their particular needs and challenges.
Modern technology is ensuring that hearing aids are lighter, smaller and more responsive. They can be modified to meet a wide spectrum of hearing loss. There are even some with the capability to pick up Bluetooth transmissions of sounds from televisions and mobile devices, for example.
One medical problem that can result in hearing loss is cortical deafness.
The way the inner and outer elements of the ear perform their different functions is intricate and really quite incredible. When one part is damaged in some way, it can create various forms of hearing loss.
However, cortical deafness is not a result of damage to the psychical mechanisms that collect sounds within the ear. It is actually damage to the part of the brain that interprets auditory (sound) input.
“Cortical” means it relates to the brain’s cortex, the outer layer of the cerebrum, which is the largest part of the brain. If this location suffers trauma of some form, it can malfunction in the way it processes auditory information. Incidentally, other parts of the cortex control other sensory functions, so you may also come across, for example cortical blindness. This is when the information from the eyes is not processed properly.
Cortical deafness is sometimes called “Central hearing loss”.
Hearing loss that is attributable to damage to the primary auditory cortex is rare. This may partly be because it is difficult to diagnose. The mechanisms of the ear will look fine when examined, and profound hearing loss may seem “inexplicable”.
Cortical deafness may also be the result of a more general medical issue which has caused damage to the brain.
This central hearing loss is believed to be a result of a lesion – an area of damage on the cortex that can arise from injury or illness, such as a wound or tumor. It could also be a birth defect.
If someone has a stroke (an obstructed or leaking blood vessel) which starves the brain of oxygen, it can damage the cortex. Some scientists believe strokes can result in a lesion on the part of the cortex that processes auditory information.
Often someone who is experiencing cortical deafness will be unable to process any auditory information, meaning that they can’t interpret any level or type of sound. Whether it is low-frequency or high-frequency sound is not an issue. If you have cortical deafness it will still be difficult to hear because it is incomprehensible.
Because the ear system still functions and some auditory input may be registered by the brain, people with cortical deafness may still instinctively turn their head and direct their ear towards sound. But their brain will be unable to make sense of the input, whether it is speech, music or noises.
Clearly for this rare condition to be diagnosed, medical intervention would have been required. The specialist will assess just how profound the hearing loss is, though cortical deafness is usually comprehensive.
If there is some degree of auditory interpretation remaining and the lesion has not completely damaged this area of the cortex, it may be possible to use an aid to boost sound quality. This could provide the remaining auditory input processes with additional information.
It is more likely, however, that you would be provided with help and information to manage profound hearing loss.
As mentioned, cortical deafness is very rare. In fact, there are believed to be only 12 reported cases.
However, if you believe that you have this condition, or your loved one is suffering from profound hearing loss, it is vital to seek medical help and a proper diagnosis.
There are many reasons why hearing loss occurs, and unlike cortical deafness, there could be solutions available to reverse or stop the condition, restoring or protecting your ability to hear.