Physicians, researchers and audiologists validate new imaging software for cochlear implant patients

Michael Canfarotta, MD, Margaret Dillon, AuD, Emily Buss, PhD, Harold Pillsbury, MD, FACS, Kevin Brown, MD, PhD, and Brendan O’Connell, MD, in the Department of Otolaryngology/Head and Neck Surgery, found that a new imaging software can be used to determine the precise location of an implant within the cochlea, which may be used to individualize the device for improved outcomes.

Physicians, researchers and audiologists validate new imaging software for cochlear implant patients click to enlarge Postoperative tomography images in the tablet-based software showing the cochlear view and cochlear dimensions.

Researchers in the UNC Department of Otolaryngology/Head and Neck Surgery have validated a new software that can be used to determine the position of a cochlear implant using post-operative computed tomography imaging. This project was led by Dr. Michael Canfarotta, a PGY-3 resident who is funded by the department’s T32 research training grant.  He and the cochlear implant research team – composed of surgeons, audiologists and basic scientists – reported excellent reliability across estimates of implant placement using this tool. This demonstrates that we can accurately capture patient-specific information about implant position for individual patients, information that can be used to help restore the natural tonotopic organization. 

The cochlea is comprised of thousands of microscopic sensory cells that work like keys on a piano. Each sensory cell is organized and tuned to match a certain pitch. This tonotopic organization is preserved throughout the auditory system, all the way to the cortex. The functional significance of this organization is not fully understood, but it seems to be critical for recognizing familiar sounds, such as understanding speech.  

Patients with moderate-to-profound hearing loss typically have experienced a loss of the sensory cells, however, the tonotopic organization of the subsequent areas of the auditory pathway are intact. A cochlear implant provides electrical stimulation, bypassing the damaged sensory cells to stimulate the auditory pathway and provide the patient with access to sound. While unique subtleties in the size of each patient’s cochlea can result in dramatic differences in intracochlear placement of the implant contacts, modern clinical practice employs a one-size fits all approach and delivers frequency information irrespective of location.  This means that a cochlear implant recipient may have to learn to recognize sounds that are shifted in frequency compared what they heard before surgery. Discrepancies between the electric frequency information provided by the implant and the normal frequency organization of the cochlea are thought to limit the benefit of the cochlear implant, particularly early in the post-operative period.

The ability to reliably determine the location of the implant in relation to the tonotopic organization of the cochlea allows researchers to program each cochlear implant patient’s device with individualized frequency filter assignments specific to the patient’s device placement. The long-term goal is to use estimates of implant position to guide cochlear implant programming, helping each cochlear implant recipient to hear better and reach their best performance sooner in the post-operative period.  

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