Assessment of the incidence and results of bilateral cochlear implantation in adults and children in France.

Multicenter retrospective study of data in the French national registry of cochlear implantations from January 1st 2012 to December 31st 2016. Functional results from CAP (Category of Auditory Performance) questionnaires and speech audiometry tests, with mono- and di-syllabic word-lists, were compared before and after implantation. Speech audiometry tests were carried out against a noisy background, except before simultaneous implantations.

Nine hundred and forty two bilateral cochlear implantations were performed during this period, that is, 16.4% of all cochlear implantations. Five hundred and eighty eight bilateral implantations were performed sequentially. 59% of the bilateral implantations were performed in children. Bilateral implants significantly improved CAP scores in all cases (P<0.001). Auditory performance, with the two types of word-list, were significantly improved after simultaneous implantation (P<0.01). After sequential implantation, the speech discrimination score, already very good with the first implant, reached 63±26% [0–100] with monosyllabic word lists, and 72±28% [0–100] with dissyllabic words. There were more complications due to surgery in bilateral cases than in the entire population of cochlear recipients (9.1% vs 6.4%, P<0.02).

Hearing is significantly improved by simultaneous cochlear implantation. For sequential implantation, at one year, when auditory results were already excellent from the first implant, in the bimodal condition CAP scores were significantly improved, although there was no further change in speech audiometry in noise.