title: A Cochlear Implant Performance Prognostic Test Based on Electrical Field Interactions Evaluated by eABR (Electrical Auditory Brainstem Responses).
abstract: Cochlear implants (CIs) are neural prostheses that have been used routinely in the clinic over the past 25 years. They allow children who were born profoundly deaf, as well as adults affected by hearing loss for whom conventional hearing aids are insufficient, to attain a functional level of hearing. The "modern" CI (i.e., a multi-electrode implant using sequential coding strategies) has yielded good speech comprehension outcomes (recognition level for monosyllabic words about 50% to 60%, and sentence comprehension close to 90%). These good average results however hide a very important interindividual variability as scores in a given patients' population often vary from 5 to 95% in comparable testing conditions. Our aim was to develop a prognostic model for patients with unilateral CI. A novel method of objectively measuring electrical and neuronal interactions using electrical auditory brainstem responses (eABRs) is proposed.
  
  
  
  The method consists of two measurements: 1) eABR measurements with stimulation by a single electrode at 70% of the dynamic range (four electrodes distributed within the cochlea were tested), followed by a summation of these four eABRs; 2) Measurement of a single eABR with stimulation from all four electrodes at 70% of the dynamic range. A comparison of the eABRs obtained by these two measurements, defined as the monaural interaction component (MIC), indicated electrical and neural interactions between the stimulation channels. Speech recognition performance without lip reading was measured for each patient using a logatome test (64 "vowel-consonant-vowel"; VCV; by forced choice of 1 out of 16). eABRs were measured in 16 CI patients (CIs with 20 electrodes, Digisonic SP; Oticon Medical ®, Vallauris, France). Significant correlations were found between speech recognition performance and the ratio of the amplitude of the V wave of the eABRs obtained with the two measurements (Pearson's linear regression model, parametric correlation: r2 = 0.26, p<0.05).
  
  
  
  This prognostic model allowed a substantial amount of the interindividual variance in speech recognition scores to be explained. The present study used measurements of electrical and neuronal interactions by eABR to assess patients' bio-electric capacity to use multiple information channels supplied by the implant. This type of prognostic information may be valuable in several ways. On the patient level, it allows customizing of individual treatments. ClinicalTrials.gov Identifier: NCT01805167.
authors.affiliation: University Head and Neck Institute, CHU de Nice, 31 Avenue de Valombrose, 06107 Nice cedex 2, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Guevara
authors.affiliation: Oticon Medical, Clinical and Scientific Research Department, 2720 chemin St Bernard, 06220 Vallauris, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Hoen
authors.affiliation: Department of Audiology and Otorhinolaryngology, Edouard Herriot Hospital, 5 Place d'Arsonval, 69437 Lyon, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Truy
authors.affiliation: Institute for Readaptation Sciences and Techniques, 8 Avenue Rockefeller, 69373 Lyon Cedex 08, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Gallego
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001309:Auditory Threshold / Q000502:physiology; D003051:Cochlea / Q000503:physiopathology*; D019929:Cochlear Implantation; D003054:Cochlear Implants; D003638:Deafness / Q000628:therapy*; D004558:Electric Stimulation / Q000379:methods; D004567:Electrodes, Implanted; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D005602:France; D034381:Hearing Loss / Q000503:physiopathology / Q000628:therapy; D006320:Hearing Tests / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D055815:Young Adult