U. WASHINGTON (US) — A patient at the University of Washington Medical Center become the world’s first recipient of a device that quells the disabling vertigo associated with Meniere’s disease.
The clinicians who developed the implantable device hope that success in a 10-person surgical trial of Meniere’s patients will lead to exploration of its usefulness against other common balance disorders that torment millions of people worldwide.
“What we’re proposing here is a potentially safer and more effective therapy than exists now,” says Jay Rubinstein, an ear surgeon and auditory scientist.
In the United States, Meniere’s affects less than 1 percent of the population. The disease occurs mostly in people between ages 30 and 50, but can strike anyone. Patients more often experience the condition in one ear; about 30 percent of cases are bilateral.
The disease affects hearing and balance with varying intensity and frequency but can be extremely debilitating. Its episodic attacks are thought to stem from the rupture of an inner-ear membrane. Fluid leaks out of the vestibular system, causing havoc to the brain’s perception of balance.
To stave off nausea, afflicted people must lie still, typically for several hours and sometimes up to half a day, while the membrane self-repairs and equilibrium is restored, says James Phillips, a research associate professor.
Because the attacks come with scant warning, a Meniere’s diagnosis can cause people to change careers and curb their lifestyles.
Many patients respond to first-line treatments of medication and changes to diet and activity. When those therapies fail to reduce the rate of attacks, surgery is often an effective option but it typically is destructive. In essence, the patient sacrifices function in the affected ear to halt the vertigo—akin to a pilot who shuts down an erratic engine during flight.
With their device, Phillips and Rubinstein aim to restore the patient’s balance during attacks while leaving natural hearing and residual balance function intact.
A patient wears a processor behind the affected ear and activates it as an attack starts. The processor wirelessly signals the device, which is implanted almost directly underneath in a small well created in the temporal bone. The device in turn transmits electrical impulses through three electrodes inserted into the canals of the inner ear’s bony labyrinth.
“It doesn’t change what’s happening in the ear, but it eliminates the symptoms while replacing the function of that ear until it recovers,” Phillips explains.
The specific placement of the electrodes in the bony labyrinth is determined by neuronal signal testing at the time of implant. The superior semicircular canal, lateral semicircular canal and posterior semicircular canal each receive one electrode array.
A successful human trial could lead the implant to become the first-choice surgical intervention for Meniere’s patients, Phillips says, and spark collaboration with other researchers who are studying more widespread balance disorders.
Cochlear Ltd. of Lane Cove, Australia, will manufacture the device.
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