title: Residual hearing thresholds in cochlear implantation and reimplantation.
abstract: Implant and reimplantation surgery should be carried out with preservation of residual hearing. The aim of this study is to evaluate the effects of such a surgery on hearing threshold. We report the results on 40 patients, 20 males and 20 females, aged between 5 and 70 (mean 29) years, 16 pre-verbal and 24 post-verbal, with measurable pre-operative auditory thresholds. We used the following implants: Advanced Bionics, Med-El, Cochlear, and MXM Digisonic. Four of the patients underwent cochlear reimplantation owing to device failure. A complete insertion was obtained in all patients. Responses to pure-tone stimuli were evaluated in each ear in pre-implant conditions and 3 months after cochlear implant or reimplantation. The explantation was performed with minimal cochlear trauma and preservation of the explanted electrode integrity. 35% showed no change of the hearing threshold, 45% showed a slight worsening of the hearing threshold level in the implanted ear, and 20% had a total loss of residual hearing. Median increases of threshold levels were 10, 5, 10 and 3 dB HL respectively for 125, 250, 500 and 1 kHz. In the group of 4 patients who underwent cochlear reimplantation, 2 showed no variation of the hearing threshold, 1 preserved an appreciable hearing threshold, and 1 had a total loss of residual hearing. The data seem to suggest that hearing function is rather resistant to mechanical trauma during implant and reimplant surgery; the authors hypothesize a role for direct spiral ganglion activation under intense mechanical stimulation.
authors.affiliation: Institute of Otorhinolaryngology, Catholic University of the Sacred Heart, Rome, Italy.
authors.forename: Walter
authors.initials: W
authors.lastname: Di Nardo
authors.forename: Italo
authors.initials: I
authors.lastname: Cantore
authors.forename: Francesca
authors.initials: F
authors.lastname: Cianfrone
authors.forename: Pietro
authors.initials: P
authors.lastname: Melillo
authors.forename: Mario
authors.initials: M
authors.lastname: Rigante
authors.forename: Gaetano
authors.initials: G
authors.lastname: Paludetti
mesh_terms: D000328:Adult; D000368:Aged; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold; D002648:Child; D002675:Child, Preschool; D019929:Cochlear Implantation; D005260:Female; D006309:Hearing; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000517:prevention & control; D011300:Preoperative Care; D011475:Prosthesis Failure; D012086:Reoperation; D013136:Spiral Ganglion / Q000502:physiology; D016896:Treatment Outcome