Immunity After Cochlear Implantation and Perilymph Molecular Profiles in Sensorineural Hearing Loss

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 signedthe surgery visit V1 with blood sample and perilymph collectionthe 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 signedthe surgery visit V1, the 1 month visit V2 and the 6 months visit V3 during which the blood sampling will be performed.

Inclusion Criteria for the "Cochlear implantation" group :Patients aged 18 years or moreIndication 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 audiometryPatients given their free and informed written consentPatients affiliated to a French social security systemInclusion Criteria for the "Control" group:Patients aged 18 years or moreIndication for otological surgery of the middle ear (excluding active infectious or inflammatory pathology e.g. myringoplasty, ossiculoplasty, cure for otosclerosis)Normal hearing (non affected inner ear): average hearing loss (mean threshold for the frequencies 500, 1000, 2000, 4000 Hz) ≤ 35 dB in bone conductionPatients given their free and informed written consentPatients affiliated to a French social security systemExclusion Criteria for the "Cochlear implantation" group:Contraindication to surgery detected during the preoperative assessmentPre-implantation cochlear assessment unfavorable to the implantation surgeryAbsence of residual hearing shown by preoperative audiometryHistory of bacterial labyrinthitis or bacterial meningitisCochlear ossification shown on preoperative imagingHomozygous pathogenic mutations identified by molecular diagnosis of the SCL26A5 (prestin), TECTB (Beta-Tectorin) genes, and heterozygous of the COCH gene (Cochlin) prior to implantation (if available)Vulnerable subject: minors, protected adults as defined by the Public Health Code, pregnant or breastfeeding women, subject under guardianship or subject deprived of libertyParticipation in another pharmacological therapeutic interventional clinical researchExclusion Criteria for the Control group:Contraindication to surgery detected during the preoperative assessmentFluctuating hearing = fluctuating hearing thresholds on at least one ear (shown by past bone conduction pure-tone audiometries)History of bacterial labyrinthitis or bacterial meningitisMiddle ear infection or inflammation on the day of the surgeryChronical immune or inflammatory diseaseActive viral or bacterial infection on the day of inclusion visit or surgeryFever on the day of the first blood sampleVulnerable subject: minors, protected adults as defined by the Public Health Code, pregnant or breastfeeding women, subject under guardianship or subject deprived of libertyParticipation in another pharmacological therapeutic interventional clinical research