Last week, a man from Yakima, Washington, became the first patient to receive an implant designed to quell the disabling attacks of vertigo that result from a condition known as Meniere’s disease. The device, developed by researchers at the University of Washington, is the first therapeutic implant to treat a disorder of the vestibular system, a set of organs in the inner ear responsible for sensing head motion and maintaining balance. The researchers hope that the device will not only help treat the disease but also pave the way for more complex devices for balance disorders.
People with Meniere’s disease experience sudden attacks that can include intense dizziness, tinnitus, nausea, and hearing loss. The attacks can last from 30 minutes to several hours, and may happen every few years to every day. There is no cure, although the condition can sometimes be treated with medications and dietary restrictions. In very severe cases, patients opt to destroy the function of the inner ear through surgery or medical treatment.
The inner ear contains a set of three structures called the semicircular canals, which function like a gyroscope by detecting the movement of fluid through the canals to sense the rotation of the head. Jay Rubinstein, an ear surgeon and otolaryngologist at the University of Washington Medical Center, explains that the brain normally receives constant input about head movement from the vestibular nerves, which are connected to each of these structures, as well as two other structures that sense horizontal and vertical movement.
Doctors believe that during a Meniere’s attack, fluid buildup in the inner ear blocks the information from the nerves in one ear, leading the brain to think that the body is turning. The implant works by electrically stimulating the vestibular nerves attached to the semicircular canals of the compromised ear during an attack, thereby compensating for the missing signal.
The new implant is a modification of a cochlear implant whose design and surgical implantation had already been approved by the FDA. The modified one consists of a surgically implanted device that contains three electrode arrays: each one is inserted into one of the semicircular canals. An external processor, worn behind the affected ear, communicates wirelessly with the internal component. When experiencing an attack, the patient can manually activate the device. At other times, it remains off. Although the device requires surgical implantation, it does not require disabling a patient’s balance system or pose the threat of hearing loss, which is the case with some of the more radical treatments for severe Meniere’s disease.