There are several functional groups that are important for hearing. These include the external ear canal and eardrum; the ossicles, or bones of the middle ear; the cochlea and the nerves that take this information to the brain. Problems with the external canal and ear drum can decrease of prevent the sound waves from reaching the inner ear. If the ossicles are damaged or destroyed, the vibrations that hit the ear drum cannot be transmitted to the inner ear. If the cochlear, or inner ear structures that converts sound waves into nervous impulses, is damaged or if the nerves that take this information to the brain are damaged, hearing will be impaired or lost. Hearing loss is usually divided into conductive hearing loss, where the sound waves are not transmitted, and sensorineural loss, where the sound is not converted into neural impulses or is not transmitted to the brain.
Causes of Hearing Impairment Or Loss
Hearing loss can be congenital or hereditary. Chronic infections of the middle ear, or spread of infection to the inner ear can lead to varying degrees of hearing loss. The outer canal, or external auditory canal, can become blocked with excessive earwax (cerumen). The ear drum or tympanic membrane can be torn, interfering with the transmission of sound waves to the ossicles. Vascular disease can lead to injury or strokes of the middle ear and the nerves that serve auditory function. Head injuries can produce fractures that damage the inner ear, the nerves from the inner ear, the ossicles, the ear drum or allow blood or spinal fluid to accumulate in the middle ear. Some diseases, such as multiple sclerosis, syphilis, or viral infection such as mumps can lead to hearing loss. Prolonged exposure to sound levels of 85 decibels or above and aging decrease hearing function, particularly to high-pitched tones.
Signs and Symptoms of Hearing Impairment Or Loss
Hearing loss has many gradations. Early on, there are problems discriminating sounds or words. This may be particularly apparent in loud environment. Ringing in the ear may occur and may persist. Dizziness and ear pain can also develop. When there is some type of head trauma, particularly trauma that leads to basilar skull fractures, there may be immediate and complete loss of hearing.
Find more information
Medical Content Last Updated on 07/12/2008
The information contained on this site is for the sole purpose of
being informative. This information is not and should not be used or relied upon as medical
advice. Always seek the advice of your physician, nurse
Or other qualified health care provider before you undergo any treatment or
for answers to any questions you may have regarding a medical condition.
If you believe you have a medical emergency, please discontinue use
of MyElectronicMD and call 911 now.
Nothing contained on or provided through the service is intended to be or is
to be used for medical diagnosis or treatment.
Your use of this site is subject to certain terms and conditions.