Multichannel vestibular implant
For people with bilateral vestibulopathy (damage to the vestibular system in both ears) walking requires constant attention to avoid a fall. Now, researchers at the Johns Hopkins Vestibular NeuroEngineering Laboratory have shown they can facilitate walking, relieve dizziness and improve quality of life in patients with bilateral vestibulopathy (BVP) by surgically implanting a stimulator that electrically bypasses malfunctioning areas of the inner ear and partially restores the sensation of balance.
The results from their study of eight patient using the device were published on February 11, 2021 in the New England Journal of Medicine.
"Although about 20 individuals had been implanted elsewhere with devices used to stimulate the vestibular nerve in a laboratory setting, participants in this trial are true pioneers. They are the first to use a vestibular implant as a long-term, 24-hour-per-day sensory restoration treatment," says senior study author Charley Della Santina.
To achieve this milestone, Della Santina and his colleagues used basic research and engineering technology to modify a cochlear implant (a device that improves hearing loss by electrically stimulating the inner ear's cochlear nerve) to instead activate the nearby vestibular nerve in response to signals from a motion sensor on the patient's head. Electrical pulse strength and timing convey information about the speed and direction of the patient's head motion which, in turn, drives head and eye reflexes that help maintain clearer vision during head movement and reduce the need to exert conscious effort to avoid falls.
In their study, the Johns Hopkins Medicine researchers evaluated eight patients with BVP who received the vestibular implant, assessing changes in postural stability, walking, hearing and patient-reported outcomes, including dizziness and quality of life. Assessments were conducted before implantation surgery (the baseline measure) and at six months and one year afterward. Median scores improved for the group on four of the five posture and gait metrics, and on three of the four patient-reported outcomes.
Watch a video [YouTube] of a patient before and after vestibular implantation.
All eight had some hearing loss in the implanted ear. Five kept enough hearing in the implanted ear to use a telephone without a hearing aid. Three had greater hearing loss.
"Improvement in performance on standardized clinical tests of balance and walking has been remarkable," says Margaret Chow, study lead author and biomedical engineering doctoral candidate at The Johns Hopkins University. "Even more gratifying is that our patients have been able to return to activities that enrich their daily lives, such as exercising, riding a bike, gardening or dancing at a daughter's wedding."
Overall, the improvement in quality of life and relief from the misery of BVH [Bilateral Vestibular Hypofunction] has been life altering, says A’ndrea Messer, PhD, one of the patients chronicled in the Johns Hopkins Medicine study and a senior science and research information officer at Penn State University.
"The multichannel vestibular implant is incredible," says Messer. "Before receiving it, I couldn't walk in the dark, on uneven ground or without a cane. Now, I can do all of those things and am living a fairly normal life."
