Feasibility of the Mi2000 Totally Implantable Cochlear Implant in Severely to Profoundly Deaf Adults.

Inclusion Criteria: * Minimum age of eighteen (18) years at time of enrolment * Bilateral sensorineural hearing loss with no or limited benefit from a hearing aid (\>70 dB HL PTA4) * Post-lingual onset of deafness * No or limited benefit from hearing aids for less than 10 years. * A maximum score of 50% on a monosyllables test in the language of the test centre in the ear to be implanted * General health condition, psychological and emotional condition deemed compatible with the treatment and tests performed in this study and realistic expectations, as deemed appropriate by the implanting surgeon/implant board * Fluency in the test language with excellent proficiency, as appropriate to perform speech testing * Evidence of up-to-date vaccinations against meningitis, as per recommendations by the applicable national body * Signed and dated informed consent before the start of any study-specific procedure Exclusion Criteria: * Lack of compliance with any inclusion criterion * Previously having received an implant on the location chosen for placing the cochlear implant * Having received a hearing implant from another manufacturer than MED-EL on the contralateral ear * Pre-existing condition known to necessitate MRI scans after implantation of the Mi2000 * Women being pregnant or nursing * Women of child-bearing age not reporting to use effective contraception * Contraindication to surgery in the middle and inner ear * Contraindication to general anaesthesia * Cochlear malformations, ossification or other obliteration of the cochlea, history of meningitis preventing placement of the electrode array, as confirmed by medical examination * Acute cholesteatoma * Acute external or middle ear infections * Perforated tympanic membrane * Known intolerance to any of the materials used for the implant or accessories * Non-functional auditory nerve and/or upper auditory pathway including a history of vestibular schwannoma * Factors preventing appropriate placement of the stimulator housing and the microphone, including fixation with screws, in the bone of the skull * Unstable Meniere's disease, Auditory Neuropathy, Epilepsy not responding to treatment * Unrealistic expectations of the subject * Permanent inability and/or unwillingness to participation in post-operative care and rehabilitation * Known intellectual disability and/or psychological diseases * Participation in other pharmacological clinical trials within four weeks prior to enrolment