HEARING LOSS MAY BE ASSOCIATED WITH DIFFERENT TYPES OF HEALTH PROBLEMS, BUT THE END EFFECT IS ONE OF TWO BASIC TYPES OF HEARING LOSS; SENSORINEURAL AND CONDUCTIVE.
Sensorineural Hearing Loss
Sensorineural hearing loss is an interference in the transmission of sound impulses from the inner ear to the brain. It is most often not reversible, but can be most can helped with amplification. Some of the important causes of sensorineural hearing loss include:
A decrease in hearing is common with age. This condition is called presbycusis. Age-related hearing loss is generally thought to be a decline in the nerve function of the ear as a person ages. The main area of injury in age-related hearing loss is in the cochlea, a snail-shell-shaped structure that generates the first electrical impulse for hearing. There is usually a loss of cells that pick up the tones, particularly in the high-frequency portion of the cochlea. As these cells are damaged, the cells lose their ability to transmit sound in the form of pitches. The degeneration may progress to involve the nerve fibers that connect the ear and brain. The loss is so gradual that a person may not know that it has happened. Most people over the age of 65 have some hearing loss and by age 80, almost everyone does
2. Noise-induced hearing loss
Intense sounds of greater than 75 decibels cause damage to the inner ear. Damage may occur because of a single exposure or from many exposures over months or years. Typically, noise produced by machines or weapons is the most damaging.. If a sound reaches 85 dB or stronger, it can cause permanent damage to your hearing. The amount of time you listen to a sound affects how much damage it will cause. The quieter the sound, the longer you can listen to it safely. If the sound is very quiet, it will not cause damage even if you listen to it for a very long time; however, exposure to some common sounds can cause permanent damage. With extended exposure, noises that reach a decibel level of 85 can cause permanent damage to the hair cells in the inner ear, leading to hearing loss. Many common sounds may be louder than you think…
A typical conversation occurs at 60 dB – not loud enough to cause damage. A bulldozer that is idling (note that this is idling, not actively bulldozing) is loud enough at 85 dB that it can cause permanent damage after only 1 work day (8 hours). When listening to music on earphones at a standard volume level 5, the sound generated reaches a level of 100 dB, loud enough to cause permanent damage after just 15 minutes per day! A clap of thunder from a nearby storm (120 dB) or a gunshot (140-190 dB, depending on weapon), can both cause immediate damage. Some examples of noises that can cause noise-induced hearing loss include: motorcycles, lawnmowers, wood working tools, loud rock music, firecrackers, and gun fire.
3. Sensorineural hearing loss
Common childhood diseases, such as mumps, measles, scarlet fever, whooping cough, meningitis, and extended high fevers can cause hearing loss. Having these diseases does not guarantee hearing loss, but these should be followed up with a hearing test.
Some medications may reduce hearing sensitivity by damaging hair cell receptors within the inner ear. These include: aminoglycoside antibiotics such as gentamicin, tobramycin, amikacin, and streptomycin; erythromycin (when given intravenously); and vancomycin (when given to patients with poor kidney function). Ménière’s disease – Ménière’s disease is thought to be due to a change in the volume of fluid inside the inner ear. The hallmark of Ménière’s disease is fluctuant hearing, spells of dizziness and a sense of fullness in the affected ear. 5. Acoustic neuroma It is also called as “vestibular schwannoma” – An acoustic neuroma is a tumor which is located between the ear and the brain, and which usually affects balance as well as hearing. In 95 percent of cases the tumor affects only one ear, and in 5 percent of cases the problem is linked to an inherited syndrome called neurofibromatosis type 2. The possibility of an acoustic neuroma should be considered when there is a hearing loss in one ear only
Conductive Hearing Loss
Conductive hearing loss is a blockage in the transmission of sounds from the ear drum to the inner ear. It is sometimes reversible with medical attention. Some of the most common causes of conductive hearing loss include.
1. Obstruction of the ear canal by ear wax or a foreign object
Sometimes the ear canal can become occluded with wax or some other object and sound cannot travel down the ear canal the way it should. If this is the case, the wax or object can be removed by a professional and hearing may improve.Cotton swabs, hair pins and other objects should never be used in the ear to remove wax. The wax is likely to be pushed down further into the ear canal and then become more difficult to remove. In addition, permanent damage can result from placing any of these objects in the ear canal. The safest solution is to have a medical professional such as a doctor, nurse or audiologist examine the ear and remove any obstructive wax or object.
2. Perforation or other damage to the ear drum
Perforations of the ear drum can be caused by various conditions such as head trauma and ear infections. When the ear drum has a hole in it, it is not able to vibrate as efficiently and pass the sound to the nerve.
3. Otitis Media
Inflammation of the ear (sterile otitis or serous otitis) may occur when there is a collection of sterile fluid in the ear. This may be caused by overproduction of fluid by the structures in the middle ear. It may also be caused by blockage of the Eustachian tube, which connects the middle ear and the back of the nose/upper throat. The presence of excess fluid causes the ear to become irritated and inflamed. Acute otitis media (acute ear infection) occurs when bacterial or viral infection develops in the fluid of the middle ear. This condition can produce hearing loss because sound cannot travel through a fluid filled space as efficiently as it can an air filled space.
A misshapen ear canal can sometimes cause a hearing loss.
Otosclerosis is an inherited disorder involving the growth of abnormal spongy bone in the middle ear. This growth prevents the stapes (stirrup bone) from vibrating in response to sound waves, thus leading to progressive conductive hearing loss. Otosclerosis is the most frequent cause of middle ear hearing loss in young adults,. Otosclerosis usually affects both ears, and is most commonly seen in women, 15 to 30 years old. The disorder can be addressed with a hearing aid or corrective surgery.