Sudden Sensorineural Hearing Loss (SSHL) or sudden deafness is a rapid loss of hearing. It usually occurs in a great extent but it may also result in complete hearing loss. It can happen at once or over a gradual period of one to three days. It usually affects only one ear. It is considered as an emergency incident and the patient should immediately consult his/her doctor.

The average age range of patients is 50 year-olds, but it concerns both older and younger age groups. Both sexes are equally affected. The patients experience mostly a sense of congestion in one ear (plugged ear), while poor hearing and tinnitus are less often. Coupled with poor hearing, half of the patients develop vertigo and instability.

Research has shown that patients who suffer from vertigo symptoms usually have poor prognosis, regarding their rehabilitation, compared with those suffering only from poor hearing. It has also been proved that the greater the auditory nerve damage, the more difficult its complete rehabilitation becomes. If starting the treatment delays for more than a 4-week period, the likelihood of improvement diminishes. On the contrary, an opportune treatment may lead to an 80% improvement, while in some cases the rehabilitation may be complete.