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Auditory Brainstem Implant vs Cochlear Implant

Jun. 14, 2024

When addressing severe hearing loss, understanding the differences between an auditory brainstem implant (ABI) and a cochlear implant (CI) is crucial. Both implants aim to restore hearing but are used in different scenarios based on the patient's specific needs.


 

Cochlear Implants: Cochlear implants are designed for individuals with sensorineural hearing loss where the cochlear nerve is still functional. These devices bypass damaged parts of the inner ear and directly stimulate the cochlear nerve to provide auditory signals to the brain. Cochlear implant surgery is a well-established procedure often performed at specialized cochlear implant centers.

Auditory Brainstem Implants: Auditory brainstem implants are typically used for patients who cannot benefit from cochlear implants due to the absence or damage of the cochlear nerve, such as in cases of neurofibromatosis type 2 or auditory nerve aplasia. ABIs bypass the cochlear nerve entirely and directly stimulate the brainstem to create auditory sensations. This makes them a viable option for patients with severe hearing loss who are not candidates for cochlear implants.

Hearing Aids vs Implants: Unlike hearing aids, which amplify sound, both ABIs and CIs provide electrical stimulation to the auditory pathway, offering a more profound solution for those with significant hearing impairments.

This article delves into the case of Jessica Toews, a patient who uniquely benefited from both an auditory brainstem implant and a cochlear implant, showcasing how these technologies can work together to enhance auditory performance.

Cochlear Implant and Auditory Brainstem Implant Work Together to Create Full Hearing Experience: Patient Case Analysis

 

Ravi N. Samy, MD, successfully implanted a cochlear implant (CI) in the right ear and an auditory brainstem implant (ABI) in the left ear of patient Jessica Toews, making her one of the few patients in the country to have both. The ABI was implanted with the CochlearTM Nucleus® 7, the first made-for-iPhone sound processor approved by the Food and Drug Administration. With the combination of the ABI and the Nucleus 7 Sound Processor, Ms. Toews can stream phone calls, video, music, and entertainment.

The Nucleus 7 and ABI were used together to create a full hearing experience. Image courtesy of Cochlear Americas, © 2017.

Ms. Toews’ story began in 2009 with a diagnosis of neurofibromatosis type 2. Doctors removed a tumor on her left ear because it was pressing on her brain stem. They planned to implant an ABI at the same time, but her insurance company denied it at the last minute. The surgery successfully removed the tumor, but she lost hearing in her left ear. Two years later, a tumor on Ms. Toews’ right auditory nerve began to grow. She enrolled in a National Institutes of Health study, and the trial drug shrunk the tumor, but the favorable response ended with the trial. Ms. Toews’ next round of treatment was chemotherapy, which stopped the growth of the tumor, but her hearing worsened.

When Ms. Toews lost hearing in her right ear, Lisa Houston, AuD, a University of Cincinnati (UC) Medical Center audiologist, suggested a CI for her right ear and that she see Dr. Samy about the procedure. Dr. Samy, director of the adult cochlear implant program at UC Medical Center and associate professor of otolaryngology at UC College of Medicine, agreed that Ms. Toews was an ideal cochlear implant candidate however recommended that she have radiation prior to surgery. Radiation successfully shrank the tumor, and three months later, in February 2017, Dr. Samy implanted the CI in her right ear. Just several weeks after surgery, Ms. Toews heard her children say “I love you” for the first time. In August 2017 – two months after the Nucleus 7 Sound Processor was approved – Dr. Samy implanted the ABI and the sound processor in the patient’s left ear. When it was activated approximately six weeks later, Ms. Toews heard sounds in her left ear for the first time in eight years. In early October, the Nucleus 7 external sound processor was moved to her right ear because it would be more effective in her better hearing ear.

Dr. Samy described Ms. Toews as an incredible patient, for her profound faith, and for her confidence and determination to overcome the health difficulties she encountered. In discussing ABIs, Dr. Samy says, “the success of the procedure hinges on a surgical team with a unique set of skills and training—one that is found in an academic center such as UC Medical Center, where three ABIs have been performed in the past six months. This volume is highly regarded since the procedure is not commonly performed.” Dr. Samy anticipates that the future use of ABIs will also include children.