Isolated Second Implant Adaptation Period in Sequential Cochlear Implantation in Adults.

Objective: To determine if depriving the use of the first cochlear implant (CI1) impacts adaptation to a sequential implant (CI2).

Study Design: Prospective cohort.

Setting: Academic center.

Patients: Sixteen unilateral cochlear implant recipients undergoing contralateral implantation (sequential bilateral) were matched according to age, etiology, duration of deafness, device age, and delay between implants.

Intervention: During a 4-week adaptation period after CI2 activation, patients underwent deprivation of CI1 or were permitted continued use of it.

Main Outcome Measures: Speech perception scores and subjective quality of life outcomes before CI2 and at 1, 3, 6, and 12-months following activation.

Results: Maximal CI2 speech perception scores in quiet were achieved by 1-month postactivation for the "deprivation" group (71.3% for hearing in noise test [HINT], p = 0.767 for change beyond 1-mo) compared with 6-months for the "continued use" group (67.9% for HINT, p = 0.064 for change beyond 6-mo). The "deprivation" group experienced a temporary drop in CI1 scores (67.9% for HINT in quiet at 1-mo versus 78.4% pre-CI2, p = 0.009) recovering to 77.3% by 3-months; unchanged from baseline levels (p = 1.0). A binaural advantage over the better hearing ear was present for HINT sentences with noise (72.4% versus 58.8% for "deprivation", p = 0.001; 71.5% versus 52.7% for "continued use," p = 0.01). Missing data precluded a meaningful analysis of subjective quality of life outcome scales.

Conclusion: Bilateral cochlear implantation improves speech perception compared with one implant. A period of deprivation from CI1 shortens time to maximum speech perception by CI2 without long-term consequences on the performance of CI1.