Sensorineural Hearing Loss Causes and Treatment
The identification and treatment of ‘sensorineural hearing loss’ (also known as SNHL) can be devastating, for it cannot be corrected either by medical or surgical procedures. But in order to understand just what this particular type of loss is and why it is important, you first need to understand just how the process of hearing works.
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What are The Sounds we Hear?
Everything produces sound when it moves. Even if that sound is barely discernible (or not discernible by the human ear) it makes a sound nonetheless.
How this happens is that when an object moves (or vibrates) it moves the air particles around it. The particles around it may be made up of water or gas or even solids like earth or metal, but most of the time it is air.
As the particles around the vibrating object move, they in turn move the particles around them creating a ‘wave’ of sound that carries the vibration from the source to your ear, at which point it is interpreted by the brain as a particular sound.
The human ear is a very delicate instrument that enables the translation of incoming sound waves into a format that your brain can recognize and understand.
These vibrations are then caught by the pinna or outer part of your ear.
After the sound is caught it is then moved into the inner part of your ear which is dedicated to hearing.
This part of the ear senses not only the waves themselves, but the changes in air pressure which it translates into an electrical signal which it relays to the brain including the determined direction of the sound as well as its spatial relationship to the person doing the hearing.
As stated before, the ear is a delicate instrument and it depends on a number of interacting parts in order to function properly. When any one of these parts ceases to function as designed it can result in loss.
Depending on which part of the ear is damaged will determine what kind of hearing loss is experienced.
Reversing hearing loss by regrowing hairs
However, scientists have long known that animals such as fish and birds are able to keep their hearing intact by regenerating the sensory hair cells found in the cochlea. In fact, mammals are the only vertebrates that are unable to do this.
Can Sensorineural Hearing Loss be Cured?
While some kinds of loss are correctable through various medical procedures or devices such as hearing aids, there are some kinds of damage which cannot be corrected.
The problem with sensorineural hearing loss is that it damages the inner or hearing part of the ear or the actual nerve pathways that extend from the inner ear to the brain.
Both of these areas are far too complex to be corrected with modern medical procedures. So what exactly is this kind of hearing loss, and how does it affect a person’s ability to hear sounds?
When sensorineural hearing loss occurs, the ability to hear faint sounds is drastically reduced.
In addition, even if speech or sounds are loud enough to be heard they can still come through as being unclear, muffled, or even garbled.
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What Causes Sensorineural Hearing Loss?
There are a number of known causes for sensorineural hearing loss, these include specific kinds of illnesses that were not treated properly, taking drugs that are toxic to the hearing parts of the ears or those specific neurological pathways, injury to the head, aging, birth defects or exposure to sudden and unexpected loud noises or being exposed to loud noises over a period of time.
Most of those who experience this kind of hearing loss have damage to the hair cells in the cochlea, where the hairs which help to move the sound waves along the inner ear are irreparably damaged in some way.
More unusually are those who experience damage to the cranial nerve or the auditory parts of the brain.
There are levels of damage that can affect the severity of ‘sensorineural hearing loss’.
If the damage is mild, it may result in muffled or garbled sounds, such as being able to distinguish one voice in a crowd of voices or being able to hear conversation when there is background noise such as music or repetitive noises.
For those who suffer from more severe cases it can result in living in a sort of isolated state.
You can hear that things are happening outside or around you, but cannot individuate between specific sounds or determine the direction that they are coming from.
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At the worst end of the scale are those who suffer a complete breakdown of the hearing process and who can no longer hear anything at all.
Some of the diseases that can lead to sensorineural hearing loss if experienced or left untreated include suppurative labyrinthitis, meningitis, mumps, measles and syphilis.
The drugs that can cause this kind of hearing loss include Aminoglycosides, Loop diuretics, Antimetabolites, and an overuse of Salicylates such as aspirin.
Can Sensorineural Hearing Loss be Treated?
When it comes to head traumas, it usually takes specific kinds of injuries to specific areas of the head such as a fracture of the temporal bone or an injury that would somehow affect the cranial nerve.
It is simpler to see how loud noises could be the cause of this kind of hearing loss, specifically as damage can occur over time through prolonged exposure to noises over 90dB (or 4000 Hz) when the safe and normal human hearing range is 20Hz to 20,000 Hz.
However, this does not mean that it is ‘safe’ to be around noises lower than 90dB, for the damage can build up over time, and unfortunately, many of those inventions that we consider to be simply a part of life in Western civilization are bordering on the dangerous level when it comes to sound.
Indeed, noises made by aircraft, lawn mowers, large trucks, trains, construction equipment and most major rock bands can be considered to be dangerous, especially if you are exposed to them over a long period of time or with any sort of frequency and are some of the common causes of hearing loss.
There is also some cause for concern with the use of iPods and Mp3 players which use ear bud style earphones to pipe loud music directly into the inner ear without the filtration of air friction to help take some of the edge off.
In the end, while there are many different kinds of hearing loss, ‘sensorineural hearing loss’ is usually untreatable by known medical procedures or devices and turns out to be a problem that most people have to learn to live with.