Sudden Sensorineural Hearing Loss (SSHL), or sudden deafness, is a rapid loss of hearing involving the inner ear or nerve of hearing. It can happen to a person all at once or over a period of a few days. It should be considered a medical emergency, because once the cells of hearing have died, the loss is irreversible. Thus a person who experiences SSHL should visit a doctor as soon as possible.
The main symptom is loss of hearing, either totally or to a lesser degree, so that voices and sounds are muffled on that side compared with the unaffected side. Many people notice it when they wake up in the morning. Others first notice if when they try to use the deafened ear, such as when they make a phone call. There is often distortion of sounds and they can sometimes even seem too loud but distorted. The loss may be associated with ringing or other noises in the ear (called Tinnitus). There may also be some loss of balance, that occasionally, is so severe that it causes vomiting (called Vertigo). Pain is unusual and is associated with a shingles type of infection that can also cause a paralysis of the same side of the face.
The best test is an audiogram (hearing test), as this will confirm the loss of hearing. Sometimes tuning fork tests are helpful, but only to indicate that something is wrong. The commonest cause of a sudden reduction of hearing is a build up of wax so the first thing to check is the ear canal. In SSHL however, the ear canal and eardrum look normal so there are few clinical signs that suggest there is a problem.
There are over 100 possible causes, but in only 10-15% of patients is a specific cause precisely identified. The medical history is important and may point to the likely cause such as infection (often viral), trauma (barotrauma or head injury), circulatory diseases, auto-immune disease, various medications that might have been taken, neurological conditions and the possibility of abnormal tissue growth. To determine the cause (or in fact, to rule out possible causes), blood tests, an MRI scan of the nerves of hearing and balance and an examination by an ENT specialist may be required.
If a specific cause is identified, the appropriate treatment can be started, although this does not guarantee that the hearing will recover. In most cases the treatment is based on “best guess” and essentially tries to help those hearing cells that haven’t died to recover. Drugs to improve the circulation of blood through the inner ear (thus bringing more oxygen) and steroids (Prednisone) to reduce any inflammatory reaction are often combined and can be helpful. Evidence suggests these treatments are most likely to be effective if started within days of the onset of the SSHL. However probably the most important treatment is rest, avoiding strenuous activities, lifting and straining. Full recovery is less likely in older people, if the loss is severe or if too much time has been lost before the diagnosis was made.
It is important to rule out any of the serious causes of SSHL but once this has been done the main problem is to adjust the loss of hearing. Total loss of hearing on one side requires advice on the social and work effects as well as warning of the potential dangers faced when crossing busy roads etc. A conventional hearing aid is only useful if there is enough hearing left that it can be “lifted” to approximate that on the good side but it may also help in the management of tinnitus. Specialised hearing aids such as CROS (Contralateral Routing of Signal) or BAHA (Bone Anchored Hearing Aid) may be helpful and work by taking sounds from your bad hearing side to the normal hearing other ear. The best option would be advised by your ENT specialist and audiologist.