Cochlear Implantation and Contralateral Auditory Brainstem Implantation

Objective Report outcomes of 2 first known cases using a cochlear implant (CI) and a contralateral auditory brainstem implant (ABI). Patients Two adult patients with postlingual sensorineural deafness. Intervention Both patients had unilateral CI insertion followed by contralateral ABI insertion. In 1 case, there was a large left vestibular schwannoma in the only hearing left ear. CI insertion was first performed in the right longstanding deaf ear. Shortly afterward during the left translabyrinthine surgery, a left ABI was simultaneously inserted. The second patient had Meniere's disease controlled initially by right translabyrinthine vestibular neurectomy but complicated by a right dead ear. When symptoms recurred she underwent left retrosigmoid vestibular neurectomy with auditory nerve preservation. This allowed left CI insertion and a subsequent right ABI insertion. Main outcome measures Pure tone audiometry (PTA), speech discrimination in quiet (SDq), speech discrimination in noise (SDn), and sound localization. Testing was performed with the following: 1) ABI activated alone, 2) CI activated alone, 3) CI and ABI activation (CI-ABI), and 4) CI linked to a contralateral routing of sound (CROS) hearing aid system (CI-CROS). Quality of life assessments were made using a validated questionnaire. Results PTA was worst with the ABI activated alone. SDq was best with the CI-CROS. Regarding SDn with noise coming from the CI side, the head shadow effect was only overcome by the CI-ABI; however, the CI-CROS worked best in the presence of noise opposite to the CI. The CI activated alone and CI-ABI produced useful sound localization. Quality-of-life assessments were best with the CI-CROS. Conclusion Bilateral sound detection seems more beneficial than unilateral in profoundly deaf cases with only 1 functioning auditory nerve. A CI-CROS may produce similar gains to a CI-ABI.