If someone suffers from bilateral vestibular hypofunction, it means that their inner ear doesn't maintain their sense balance properly. As a result, the person gets dizzy very easily. A new implant, however, appears to bypass the problem, significantly reducing vertigo.
Bilateral vestibular hypofunction (BVH) can be quite a debilitating condition, as it causes the sufferer to stumble and weave back and forth when walking. Not only does this greatly inconvenience the person and make them feel self-conscious, but it also puts them at a high risk of falling.
Even when someone with BVH remains seated, their head movements alone still cause their vision to blur and jump. Sufferers are therefore advised not to perform activities such as driving, in which their vertigo could endanger themselves or other people.
Treatment typically consists of performing vestibular rehabilitation exercises, and avoiding medications that may damage the inner ear or suppress brain function. Unfortunately, though, taking such measures doesn't always make that much of a difference.
Seeking a more effective alternative, scientists at the Johns Hopkins University School of Medicine started by modifying an existing cochlear implant. Ordinarily, the device would help deaf people to hear by stimulating the cochlear nerve. After being modified, however, it instead stimulated the inner ear's vestibular nerve, located nearby.
The timing and intensity of its stimulating electrical pulses were dictated by a linked motion detector, mounted on the person's head. In this way, every time their head moved – either on its own, or as part of a whole-body activity such as walking – the implant was triggered to stimulate the defective vestibular nerve. In someone without BVH, that nerve would fire on its own, in response to head movements.
For the study, eight BVH patients had an implant surgically placed in one ear, plus they were equipped with a motion detector. When the volunteers were assessed six months and then a year later, they were found to have significantly improved in four of the five measured posture and gait metrics, and in their own self-reported outcomes.
That said, all eight test subjects did experience some hearing loss in the one ear. Five of them were still able to use a telephone without utilizing a hearing aid, but the other three were not. Nonetheless, the scientists are overall quite pleased with the results.
"Improvement in performance on standardized clinical tests of balance and walking has been remarkable," says doctoral candidate Margaret Chow, who led the study along with Dr. Charley Della Santina. "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."
The research is described in a paper that was recently published in the New England Journal of Medicine. A before-and-after video of one of the patients can be viewed below.
It should be noted that a team at the University of Washington Medical Center previously developed an inner ear implant for treating Meniere's disease, which is one of the causes of BVH.
Source: Johns Hopkins Medicine