Quality of insertion in cochlear implants : a clinical and temporal bone study Daniele de Seta To cite this version: Daniele de Seta. Quality of insertion in cochlear implants : a clinical and temporal bone study. Sensory Organs. Université Pierre et Marie Curie - Paris VI; Università degli studi La Sapienza (Rome), 2016. English. NNT : 2016PA066174. tel-01408709 HAL Id: tel-01408709 https://tel.archives-ouvertes.fr/tel-01408709 Submitted on 5 Dec 2016 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. 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Université Pierre et Marie Curie Sapienza Università di Roma Ecole doctorale Physiologie Pathophysiologie et Thérapeutique Scuola di dottorato in Neuroscienze Clinico Sperimentali e Psichiatria Laboratoire INSERM UMR 1159 “Minimally Invasive Robot-Based Hearing Rehabilitation” Quality of Insertion in Cochlear Implants: A Clinical and Temporal Bone Study Daniele De Seta Joint PhD thesis Co-Director: Prof Olivier Sterkers Co-Director: Prof Patrizia Mancini Co-Encadrant: Dr Yann Nguyen Defended in Rome, May 24 2016 Dissertation committe: Prof Gaetano Paludetti Prof Jean Marc Edeline Prof Christophe Vincent Prof Adelchi Croce II A Francesca III IV Aknowledgements First of all I would like to express my sincere gratitude to my directors and coordinators Professor Olivier Sterkers, I am grateful to you for giving me the opportunity to work in your research unit for carry out this thesis under joint supervision and later for having me proposed to be part of your group in the hospital. Thank you for continuing to share your knowledge and for being a guide for me in this project, it is a privilege and an honor to have you as a mentor. Doctor Patrizia Mancini, Thank you for having introduced me in the world of the cochlear implants, and for making this joint project possible. Doctor Yann Nguyen, My “co-encadrant” of this thesis, thanks for everything. Your support and help in the accomplishment of this project have been essential. Professor Roberto Filipo, Thank you for introducing me to the otology and the cochlear implants, for guiding me during the residency and for beginning this project. V I thank the committee members Prof Gaetano Paludetti and Dr Jean Marc Edeline that accepted to read and evaluate my work. Prof Christophe Vincent that accepted to came in Rome just for one day to be part of the committee. Prof Adelchi Croce that accepted to be part of the committee. Dr Evelyne Ferrary, Thank you for the help, for your teachings and your support given during these years spent in the lab. Thank you for all the time spent on the countless corrections and re-readings of articles, abstracts, posters and powerpoints… Dr Isabelle Mosnier, Thanks for your help in the writing and re-writing of the papers that finally have been accepted! Thanks for your trust and confidence. Dr Jean Loup Bensimon, Thank you for the cone beam CT acquisition and for your help in the analysis of the images Prof Dominique Heymann and Jerome Amiaud, Thank you for accepting to take part of this project giving me the possibility to perform the histologic analysis in your lab in Nantes. VI My collegues and friends in the lab Dr Renato Torres, gracias por todo amigo mio! Dr (PhD!) Guillaume Kazmitcheff, thanks for all the time spent togheter in the lab and outside…NYC, Grenoble, you never came in Roma! Dr Elisabeth Mamelle, when I met you in Beaujon (it was long time ago…) I never imagined to work with you in the lab and later in the hospital! I would like to thank: The French Society of Otolaryngology (SFORL) for the 2013 research grant that partially financed this thesis. MEDEL company, in particular to Dr Michel Beliaeff, Dr Samia Labassi and Dr Vincent Pean, for the unconditional support of material (MedEl Flex 28 dummy arrays), the help in the statistical analysis of the data and the sponsorship for the participation to congresses. Last but not the least, I would like to thank my family, My father, the reference for me in ENT, My mother, who always supported whatever the choice, Claudia, because is my sister! VII VIII Abstract The cochlear implantation represents the standard technique to restore the hearing in totally deafened persons, and the indications during the last years are widening also to patients with residual hearing or presenting single sided deafness. Despite the overall good to very good results after cochlear implantation reported in literature a wide heterogeneity of the hearing outcomes emerges in the single studies and poor results both in unilateral and bilateral cochlear implantation are still reported. Several patients’ specific factors have been identified as affecting postimplant speech perception score, including duration of deafness, residual preoperative speech recognition, and different speech coding strategy. In this thesis the anatomy of the cochlea and the position of the electrode array in implanted patients have been studied with the attempt to identify the affecting factors that contribute to the variability of the inter- and intra-individual speech discrimination scores both in bilaterally and unilaterally implanted patients. Moreover, following the expanding indication for cochlear implantation, the preservation of inner ear structures is becoming recommended for all cochlear implant candidates, regardless of their preoperative hearing. A radio-histological temporal bone study with a motorized insertion of the array was performed in order to identify the insertion forces parameters that could predict the possible traumatism involving the inner ear. The results of this thesis showed a relationship between the intracochlear electrode position and hearing performance in the short term follow up, whereas the neural plasticity would play an important role in the adaptation of the cochlear implant to the neural structures in the long term. A correlation between insertion forces and inner ear traumatism was found in temporal bones. Two different force profiles for traumatic and atraumatic insertion were obtained; these values, if confirmed by further studies, could be useful for the development of future force feedback automated cochlear implant insertion tool in order to reduce the risk of insertion related damage and provide the best chance for an optimal hearing rehabilitation in cochlear implanted candidates. Keywords: cochlear implants, electrode position, cochlear anatomy, insertion forces, hearing performance, long term. IX R ésumé L'implant cochléaire représente le dispositif de référence pour réhabiliter l'audition des patients atteints de surdités sévère à profonde. Les indications se sont récemment étendues vers les patients avec une audition résiduelle avec de bons résultats. Il persiste cependant une grande hétérogénéité des résultats auditifs. Plusieurs facteurs ont été identifiés comme influençant les performances auditives: durée de la surdité, intelligibilité préopératoire et stratégie de codage. Dans cette thèse, l'anatomie de la cochlée et la position postopératoire du porte-électrodes ont été étudiés afin d'identifier les facteurs de variabilité de la discrimination vocale inter- et intra-individuelle. Les résultats de cette thèse ont montré un lien entre la position de l'électrode et les performances auditives à court terme, alors que la plasticité neuronale pourrait jouer un rôle important dans l'adaptation de l'implant cochléaire aux structures neurales à long terme. De plus, la préservation des structures cochléaires est maintenant recommandée pour tous les candidats à l’implantation, quelle que soit leur audition préopératoire. Une étude radio-histologique sur rochers avec une insertion motorisée du porte-électrodes a été réalisée afin d'identifier les paramètres des forces d'insertion qui pourraient prédire le traumatisme de l'oreille interne lié à l’insertion. Une corrélation entre les valeurs de forces d'insertion et le traumatisme cochléaire a été trouvée dans les os temporaux. Ces valeurs, serviront au développement d’outils d'insertion « intelligents » pour réduire les lésions liées à l'insertion et ainsi conduire à des conditions de rééducation auditive optimale. Mots-clés: implant cochléaire, position de l'électrode, anatomie cochléaire, forces d'insertion, performances auditives, long terme X Riassunto L'impianto cocleare rappresenta il gold standard per la riabilitazione dell'udito nei soggetti affetti da sordità grave e profonda bilaterale; le indicazioni durante gli ultimi anni si stanno ampliando anche per i pazienti con udito utile parzialmente conservato sulle basse frequenze o sordità unilaterali. Nonostante gli ottimi risultati uditivi postimpianto riportati in letteratura una vasta eterogeneità dei risultati emerge nei singoli studi e pazienti con scarsi risultati sia dopo impianto cocleare unilaterale che bilaterale vengono ancora riportati. Diversi fattori paziente specifici sono stati individuati nell’influenzare le performance postimpianto tra i quali la durata della sordità, l’udito residuo preoperatorio, e le differenti strategie di codifica del segnale da parte del processore. In questo lavoro