A new clinical trial underway at UCSF, High-Resolution CT-Guided Cochlear Implant Programming, aims to improve speech and music perception for cochlear implant (CI) users.
“This personalized medicine approach to cochlear implantation is based on a patient's individual anatomy,” said UCSF’s Charles Limb, MD, chief of the Division of Otology, Neurotology and Skull Base Surgery and director of the UCSF Douglas Grant Cochlear Implant Center. “The implant is programmed according to the patient’s CT scan as opposed to a generic program.”
Music perception as the standard for perfect hearing
The default programming, also known as mapping, currently used in CIs often results in the recipient experiencing a pitch-place mismatch between the stimulation by an electrode in response to a given frequency and the actual frequency specified by the original cochlear location. While CIs can restore the user’s ability to hear one person speaking, perception of more complex auditory stimuli like music is severely limited. CI users often report listening to music as being difficult or even displeasing. These experiences can be immensely frustrating, especially for people who experience deafness later in life and have built strong emotional attachments to music.
“Music is the most challenging form of sound for cochlear implant users and therefore represents an ideal target for assessing how closely cochlear implants have come to restoring perfect hearing,” said Limb. “Previously, cochlear implant performance was measured by speech perception. The goal of this trial is to show that, in addition to speech metrics, pitch and musical metrics are improved with personalized programming of cochlear implants.”
Limb leads the Sound and Music Perception Lab at UCSF, which explores music perception and complex sound processing in CI users as well as the neural substrates of musical creativity. He was named one of the Kennedy Center Next 50—leaders who "are lighting the way forward" through their work.
Novel study with new CI recipients
The novel aspect of this clinical trial involves working with new CI recipients and performing CT-based custom CI programming at the time of first implantation. Previous CT-based CI programming studies were conducted in populations whose CIs were initially programmed with default settings.
Limb and other researchers recently published a study that examined the sources of variability for cochlear duct length (CDL) measurements in order to develop standardized landmarks for CT-based CI pitch mapping. They concluded that using the posterior edge of the round window and lateral bony wall as standardized anatomical parameters for CDL calculations improved pitch-map calculations.
For this clinical trial, Limb and the UCSF team are using flat panel computed tomography (FPCT), 3D curved multiplanar reconstruction (MPR) software and applied mathematics to measure cochlear duct length, determine intracochlear electrode location relative to standardized cochlear landmarks and create individualized frequency allocation tables relevant to the physical location of CI electrode contacts.
The team will characterize the impact of long-term personalized pitch-place maps on speech and music metrics and compare the performance of the CIs programmed using FPCT to those programmed with the manufacturer default settings. Implementing custom, FPCT-based programming for CI recipients on the first day of activation provides a unique opportunity to minimize pitch-place mismatch from the outset.
“We are actively working on ways to improve outcomes for patients with cochlear implants using approaches that have never been tried before,” said Limb. “We hope this will be the standard of care in the future.”
To learn more
UCSF Douglas Grant Cochlear Implant Center
Phone: (415) 353-2464 | Fax: (415) 353-2603