The inner ear is a delicate structure containing tiny hair cells, also known as nerve endings. These special cells hear sounds, transmitting them to the brain as electrical signals, which travel along nerves.[1] The brain then translates these signals into words and noises.
Causes and Risk Factors
When damage to the tiny hair cells within the inner ear or auditory nerve occurs, hearing loss is generally the result. Nerve deafness is not reversible. There are a variety of known causes and risk factors related to SNHL. They include the following:
- Family history/genetics;
- Birth injury;
- Acoustic trauma;
- Barotrauma;
- Head trauma;
- Ototoxic medications;
- Diseases, including vascular and Meniere’s;
- Acoustic neuroma;
- Viral and bacterial infections, including herpes simplex and zoster, influenza, measles, meningitis, mononucleosis, mumps, syphilis, scarlet fever, and toxoplasmosis; and
- Presbycusis (aging). [2,3,4]
Children may be born with SNHL (congenital hearing loss) due to more than 400 known genetic syndromes or from an infection passed along from his or her mother during pregnancy, such as herpes, rubella, or toxoplasmosis.
As much as patients want an answer or a reason for their hearing loss, unfortunately, there are times when the cause cannot be found.
Signs and Symptoms of Hearing Loss
Individuals may experience mild to profound hearing loss, either gradually or suddenly. What can or cannot be heard is attributed to one of four degrees of hearing loss the patient experiences:
- Mild loss -- Individuals can hear sounds at or above 20-40 decibels (dB);
- Moderate loss -- Individuals can hear sounds at or above 45-60 dB;
- Severe loss -- Individuals can hear sounds at or above 65-85; and
- Profound loss (deaf) -- While individuals are considered deaf at this level of loss, they may be able to hear sounds at or above 90 dB.[5,6]
Hearing impaired persons may have trouble hearing faint sounds at a mild loss. Severe loss may prohibit individuals from hearing loud noises more than a foot away.
Other symptoms may occur alongside hearing loss, including: Tinnitus (ringing in the ears), vertigo, fever, drainage (such as blood or fluid), ear pain, hyperacusis (sounds appearing louder than normal), difficulty understanding female voices or conversations amongst background noise, and sounds are muffled or distorted. [7,8]
Disclaimer: The preceding article is for informational purposes only. Licensed healthcare providers known as an otolaryngologist and audiologist should make a proper diagnosis.
Sources:
MedlinePlus website. Sensorineural Deafness. Accessed January 15, 2011.[1,8]
eMedicine Health website. Hearing Loss. Accessed January 15, 2011.[2,7]
MedlinePlus website. Hearing Loss. Accessed January 15, 2011.[3]
South Dakota Department of Health. Newborn Hearing Screening Program: Types of Hearing Loss. Accessed January 15, 2011.[4,5]
MassGeneral Hospital for Children website. Hearing Loss. Accessed January 15, 2011.[6]
Sarah Mitchell - The author has had the love of the written word since she was a young child, and one could usually find her with a book between her hands. ...
