Many patients receiving cochlear implant (CI) have some residual hearing prior to implantation surgery. However, approximately one third of them will lose it in next 6 months after cochlear implantation. Although the mechanisms involved in the residual audition loss remain unknown, animal experiments suggest the role of inflammatory or immune reaction in the cochlea. The goal of this project is to search in the perilymph (a fluid which fills the scala vestibuli and scala tympani of the cochlea) some predictive biomarkers of the residual hearing loss using modern proteomics and immunological techniques. A parallel search for blood biomarkers of post-implantation residual hearing loss and for molecular and cellular evidences of immune response to cochlear implantation will be performed.
The study will recruit 50 subjects-candidates for cochlear implantation surgery; 30 normally hearing individuals eligible for other types of otological interventions will form a control group. For all the participants blood samples will be collected and preserved. In addition, the perilymph sampling will be performed during cochlear implantation surgery.
This project relies on the calculation that from 50 patients post-cochlear implantation, 15 patients will form a group with maintained residual hearing and 15 will display delayed hearing loss. For these 30 subjects together with the control group the blood biomarkers search will be performed.
For the group of implanted patients, the follow-up will last for 12 months with 6 visits in total :
* the inclusion visit V0 during which the study will be presented and the consent form will be signed * the surgery visit V1 with blood sample and perilymph collection * the activation visit V2, 1 month ± 1 week after V1, visit V3 3 months ± 7 days after V1, V4 6 months ± 7 days after V1, V5 12 months ± 1 month after V1. During each of this visit blood sampling will be performed.
For the control group, the follow up will be 6 months long with 4 visits in total arranged during the routine follow-up appointments:
* the inclusion visit V0 during which the study will be presented and the consent form will be signed * the surgery visit V1, the 1 month visit V2 and the 6 months visit V3 during which the blood sampling will be performed.
Patients aged 18 years or more
Indication for the cochlear implantation surgery according to the criteria of French National Authority for Health (Severe to profound sensorineural deafness with indication for cochlear implant surgery: Intelligibility less than or equal to 50% when performing vocal audiometry tests with Fournier's list in free field with recent devices.)
Presence of "useful" residual hearing ≤ 80 dB on at least 2 consecutive frequencies (in air conduction) from the range 125, 250, 500, 1000 kHz on pure-tone audiometry
Patients given their free and informed written consent
Contraindication to surgery detected during the preoperative assessment
Pre-implantation cochlear assessment unfavorable to the implantation surgery
Absence of residual hearing shown by preoperative audiometry
History of bacterial labyrinthitis or bacterial meningitis