Sudden Sensorineural Hearing Loss

Sudden Sensorineural Hearing Loss

Imagine waking up tomorrow feeling dizzy, nauseous, and your ears just will not stop popping. What is wrong? After about two weeks of experiencing this all the time, you go to doctor after doctor trying to find out what in the world is wrong with you. Soon, you find your self at an otolaryngologist, a doctor that specializes in the inner ear. He finally diagnoses you with Sudden Sensorineural Hearing Loss (SSNHL). When I was ten years old, after going to some five different doctors, I was diagnosed with Sudden Sensorineural Hearing Loss Syndrome.

In order to understand the loss of hearing, we must first understand how we hear and what it means to us. Hearing all begins by the creation of a sound. Then the "sound waves are collected by the outer ear and channeled along the ear canal to the eardrum." After that, "when the sound waves reach the eardrum, the impact creates vibrations, which are transferred through a series of three tiny bones" (http://www.a1-hearingaid.com/howwehear.htm). Finally, a signal is sent to the brain and we hear the sound being made. If this process is altered in any form or fashion, it could result in hearing loss. The three basic types of hearing loss are: conductive hearing loss, sensorineural hearing loss, and mixed hearing loss. Conductive hearing loss "occurs when the eardrum, bones and membranes don't properly transmit vibrations to the cochlea..." this may be caused by a traumatic head injury or the patient could have been born with a birth defect (http://www.a1-hearingaid.com/howwehear.htm). Sensorineural hearing loss "is characterized by deterioration of the cochlea." These causes may include the 'aging process, excessive exposure to loud noise', viral infection or in some cases, it may be spontaneous (http://www.a1-hearingaid.com/howwehear.htm). This type of hearing loss is irreversible. Mixed hearing loss is simply a combination of conductive and sensorineural hearing losses.

"Most otolaryngologists define Sudden Sensorineural Hearing Loss as a "...loss that is greater than 30 decibels (dB) in three contiguous frequencies and that occurs over a period of less than 3 days" (http://deafness.about.com/gi/dynamic/offsite.html). After much clinical study, it has been determined that SSNHL occurs in 5-20 persons out of every 100,000 per year. "The natural history of SSNHL is that about 65% of patients recover their hearing spontaneously. Negative prognostic factors are thought to be: age less than 15 years or older than 65 years..." of age, these patients are less likely to regain their hearing (http://icarus.med.utoronto.ca/carr/manual/ssnhl.html). It has also been found that persons of these age groups are at an increased risk of losing their hearing in their opposite ear. "Positive prognostic factors are: seeking medical treatment within 10 days of onset, mid-frequency or up-sloping hearing loss..." this would improve the patient's likelihood of treating the effects of SSNHL (http://icarus.med.utoronto.ca/carr/manual/ssnhl.html). " Most cases of sudden SNHL are idiopathic and little is known about its pathophysiology." Three theories regarding SSNHL are the viral theory, vascular theory, and the membrane rupture theory. According to the viral theory...

Several studies support viruses as the etiology of sudden SNHL. Mumps, measles, herpes zoster, and infectious mononucleosis may involve the labyrinth as part of a recognized clinical disease. However, viruses that cause upper "respiratory tract infections" such as adenovirus have also been postulated to cause sudden SNHL (http://deafness.about.com/gi/dynamic/offsite.html).

In any case, unlike many upper respiratory infections, SSNHL is neither epidemic nor seasonal.

The vascular theory holds that partial or complete occlusion of the cochlear vasculature may cause idiopathic sudden SNHL. There are several clinical disease states that have been shown to cause sudden hearing loss by disrupting the blood supply to the labyrinth (http://deafness.about.com/gi/dynamic/offsite.html).

Also vascular spasms have been thought to be a factor in SSNHL due to reports of migraine headaches causing temporary, or reversible hearing loss. The membrane rupture theory is based upon the rupture of the "delicate inner ear membrane and fistulae of the round and/or oval window."