Sudden hearing loss - or sudden sensorineural hearing loss - is defined as a loss greater than 30dB in three contiguous frequencies, occurring over a period of less than three days.
Sudden sensorineural hearing loss (SSHL) may be noticed upon awakening in the morning or develop rapidly over hours or days. You may hear a 'pop' in the ear prior to the hearing loss.
70% of Sudden sensorineural hearing loss patients also suffer from tinnitus. Vertigo is present in 50% of the Sudden sensorineural hearing loss cases.
Causes of sudden hearing loss
Among the many possible sudden hearing loss causes are:
- Viral infections. One in four patients with SSNHL reports sufferering from an upper respiratory infection within a month before the hearing loss. Viruses associated with sudden hearing loss include mumps, measles, rubella, as well as meningitis, syphilis and AIDS, among many others.
- Tumours. A variety of tumours in the ear, benign as well as malignant, may cause SSNHL.
- Head trauma affecting hair cells, eardrum or bones. Partial or total recovery from head injury induced hearing loss can be expected.
- Drugs and insecticides. A long list of prescription drugs and chronic abuse of painkillers may cause sudden hearing loss. Insecticides such as melathion and methoxychlor have been associated with sudden hearing loss in both ears (binaural sudden hearing loss).
- Immunological disorders.
- Vascular disorders disrupting blood flow to the ear.
- Developmental abnormalities.
- Idiopathic disorders, such as multiple schlerosis, Meuniere's disease and others.
Incidents of Sudden sensorineural hearing loss are mostly unilateral, only 2% experience a case of bilateral sudden sensorineural hearing loss. In 55% of cases, the hearing loss occurs in the left ear. The incidence increases with age: 4.7 out of 100,000 people aged 20-30, and 15.8 per 100,000 in those 50-60 years of age. There are equally as many men as women who experience sudden sensorineural hearing loss.
Spontaneous recovery occurs in 32-79% of the cases, usually within the first two weeks. The chances of full hearing recovery are smaller for patients with severe loss of hearing and when the sudden sensorineural hearing loss is accompanied by vertigo. The younger the patient, the greater the likelihood of a full recovery.
Treatment of sudden hearing loss
Just as the precise source of your sudden hearing loss may be hard to pinpoint, it may be difficult to treat. It is strongly advised to see your doctor for a sudden hearing loss treatment on an emergency basis as soon as possible after the occurrence of SSNHL in order that causes demanding immediate attention may be determined or eliminated.
However, the usefulness of medical sudden hearing loss treatment of itself is debatable. Whereas some specialists favour aggressive treatment of underlying causes in the hope of reversing or curing many cases of sudden hearing loss, others conclude based on earlier studies that their patients are equally likely to regain their suddenly lost hearing fully or partially whether they receive treatment or not. However, some recent studies indicate improved results in patients receiving some forms of steroid therapy when this treatment is deemed appropriate.
Among the 30 percent to 70 percent of the patients whose sudden hearing loss becomes permanent, treatment options vary from hearing aids to cochlear implants.
In the vast majority of sudden hearing loss cases, one ear is affected. Unilateral hearing loss particularly affects communication in situations with background noise.
For the majority of the patients who do not recover their hearing by a sudden hearing loss treatment, hearing aids and assistive listening devices are the best treatment. Cochlear implants may be considered for the small fraction of SSNHL patients with severe to profound bilateral hearing loss. In cases of severe or profound unilateral hearing loss, the most common treatment includes a bone anchored hearing aid (BAHA) - a hearing implant that is placed in the skull behind the ear.
Source: Hearing Review, December 2003, Sudden Sensorineural Hearing Loss special issue and www.utmb.edu