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Stop the World From Spinning!
World’s First Vestibular Implant Attempts to Treat the Vertigo of Ménière’s Disease
By Robin Latham
With Ménière’s disease, you
may feel as if everything around
you is violently spinning.
Imagine walking down the street when you suddenly hear a roaring in one ear and everything around you begins to violently spin. You might drop to your knees, unable to control the overwhelming dizziness and nausea that is likely to keep you confined to a dark, quiet room for several hours or more until it gets better. Even worse, now that it has happened, you will never know when, or if, it will happen again.
This is what life is like for someone with Ménière’s disease, a balance disorder that affects approximately 600,000 people a year in the United States, and primarily strikes adults between 40 and 60 years old. Most people only experience problems in one ear, but a small minority will have attacks in both. Researchers still aren’t entirely sure what causes the tinnitus and vertigo of Ménière’s disease, although they do know that it has to be the result of some kind of disturbance in the vestibular system that helps us maintain our sense of balance. The treatments currently available for Ménière’s disease aren’t always effective and some can only end the dizziness by causing hearing loss. Some people are never able to find relief from their disabling symptoms and live with the uncertainty and the attacks of dizziness for the rest of their lives.
This could begin to change, thanks to the work of Jay Rubinstein, M.D., Ph.D., James Phillips, Ph.D., and their patient, a 56-year-old man with Ménière’s disease who is the world’s first recipient of an implanted device designed to stop the severe vertigo associated with the disease. The device is the result of more than four years of NIDCD-supported design and experimentation by Drs. Phillips and Rubinstein, directors, respectively, of the Clinical Vestibular Laboratory and the Virginia Merrill Bloedel Hearing Research Center at the University of Washington’s Department of Otolaryngology–Head and Neck surgery, and their team in Seattle.
Our balance is established by a series of signals that originates in the loops and pouches of three semicircular canals, located in the bony labyrinth of the inner ear. These signals are transmitted to the vestibular nerve that, in turn, sends them as electrical pulses to the brain. The semicircular canals are filled with endolymph, a fluid that is essential to the transmission of the signals. The symptoms of Ménière’s disease are thought to stem from the rupture of the semicircular canal membranes and the leaking of endolymph, which breaks down the signaling mechanism with the vestibular nerve.
“The best hypothesis for what occurs during an attack of Ménière’s disease is that the ear involved shuts off,” says Dr. Rubinstein. “That leaves only one ear to send positional information to the brain.” The result is a sensation of severe, swirling vertigo.
The University of Washington device attempts to stop a Ménière’s attack by restoring a stable pattern of electrical activity in the vestibular nerve of the damaged ear. The device uses the same technology found in a cochlear implant, a medical device that currently provides a sense of sound to more than 188,000 deaf or hard-of-hearing people worldwide.
Like the cochlear implant, the vestibular implant consists of a wireless processor worn behind the affected ear and an implanted device almost directly beneath it. Instead of traveling to the cochlea, however, the electrodes snake into the three semicircular canals—one in each canal. In addition, a handheld controller uses push buttons to start and stop a range of electrical stimuli that can be directed to any or all of the electrodes. The rates and intensities of these signals are customized to each patient.
According to Dr. Rubinstein, at the first warning signs of an attack—usually either an extreme feeling of pressure in the ear or roaring tinnitus—an individual wearing the implant only has to push the buttons until he or she finds a series of signals that may make the symptoms retreat. “They can start by stimulating one of the semicircular canals—the one that we think is the most likely to control their symptoms,” says Dr. Rubinstein. “But that could change the symptoms in such a way that we’ll need to activate the other canals as well.” Once the dizziness is gone, the controller is turned off.
The first of ten patients in the surgical trial—a man whose symptoms have resisted treatment for the past two years—was implanted with a device this past October. Dr. Rubinstein and his team have been calibrating the device and programming the controller with different electrical stimuli rates and intensities that can be sent to any one of the three electrodes in the semicircular canals.
Next, they’ll be sending the patient back to his home with the handheld device to see how successful it is in fending off attacks. Depending on the results, the medical team will begin to implant the others in the trial group.
The current standard of treatment for Ménière’s disease is to prescribe medications to control the vertigo and nausea, and diuretics to reduce the amount of fluid the body retains, which may help lower fluid volume and pressure in the inner ear. A recently FDA-approved device that fits into the outer ear and delivers intermittent air pressure pulses to the middle ear has also been successful for some people. But there are still many people with Ménière’s disease whose only options are invasive and involve surgery.
“There are a variety of surgical procedures to treat Ménière’s disease,” says Dr. Rubinstein, “because none of them are optimal.” All of them involve destroying the ear in some way. This includes the use of an antibiotic, gentamicin, which is injected through the eardrum to reach the inner ear. Although gentamicin helps reduce dizziness by reducing balance sensation, it occasionally also destroys sensory cells in the cochlea and causes permanent hearing loss.
If the University of Washington implantable device is successful in the trial patients, doctors will have another option for people with Ménière’s disease that resolves their vertigo and spares their hearing. Moreover, if it is found to help control vertigo—a symptom of a number of balance disorders—it may be useful in the treatment of many more people as well.