**5. Adults with UHL and accompanying severe tinnitus treated with a cochlear implant**

Prolonged spontaneous tinnitus of some degree is experienced by up to 20% of the adult population with exact estimates varying according to the tinnitus

definition used. Subjects with tinnitus report poor speech perception, difficulty falling asleep, difficulty concentrating, insecurity, and in many cases depression. For some people their tinnitus is persistent, debilitating, and has a negative impact on their quality of life, even when present in only one ear [38–40].

The use of a CI primarily to suppress tinnitus has been considered for those patients who have incapacitating tinnitus and a UHL and thus would not normally meet the standard criteria for CI. Studies have shown the CI has successfully been used to treat the tinnitus symptoms with the benefits lasting long term [11, 41, 42]. The CI is also able to restore true binaural input for these patients providing them with the advantages of binaural hearing for listening in noise and sound localization.

The impact of cochlear implantation on the reduction of tinnitus is wellestablished; in addition to improvements in hearing, a statistically and clinically significant reduction in the loudness and disability of tinnitus is reported. Longterm studies reporting results up to 10 years after activation also show continued reduction of tinnitus loudness to very low levels and 100% continued device use. A hypothesis is that routine daily use of the implant leads to residual tinnitus inhibition with prolonged time constants. In some patients this residual inhibition could last overnight (i.e., the switch-off period) and occasionally provides full tinnitus inhibition during day and night as reported regularly in studies with conventional CI candidates with less burdensome tinnitus [43–46].

Patients with tinnitus and SSD feel considerably worse off than those with tinnitus alone and similarly disadvantaged to more traditional implant candidates with bilateral hearing loss. Cochlear implants can reduce or suppress incapacitating tinnitus in patients with unilateral, severe-profound sensorineural hearing loss and normal contralateral hearing. It is a valid and effective therapy when other treatments have failed. The impact on quality of life of the CI on these two groups is equivalent, and a CI should be considered as an effective treatment for this population.

The reduction of tinnitus after cochlear implantation may be due to several mechanisms, such as habituation, acoustic masking, direct stimulation of the cochlear nerve, and reorganization of cortical areas.

The result was more in favor to make CI treatment in cases with short period of tinnitus (<5 years).
