A University of Washington Medical Center patient on Thursday,
Oct. 21, will be the world’s first recipient of a device that aims
to quell the disabling vertigo associated with Meniere’s
disease.
The UW Medicine 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.
The device being tested a cochlear implant and processor with
re-engineered software and electrode arrays represents four-plus
years of work by Drs. Jay Rubinstein and James Phillips of UW’s
Department of Otolaryngology-Head and Neck Surgery. They worked
with Drs. Steven Bierer, Albert Fuchs, Chris Kaneko, Leo Ling and
Kaibao Nie, UW specialists in signal processing, brainstem
physiology and vestibular neural coding.
“What we’re proposing here is a potentially safer and more
effective therapy than exists now,” said Rubinstein, an ear surgeon
and auditory scientist who has earned a doctoral degree in
bioengineering and who holds multiple U.S. patents.
In the United States, Meniere’s affects less than one 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. Endolymphatic 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, said Phillips, a UW
research associate professor and director of the UW Dizziness and
Balance Center. 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 ablative (destructive) in nature. 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.
Forever after, the person’s balance and, often, hearing are based
on one ear’s function.
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’s an override,” Phillips said. “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.”
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 National Institutes of Health grant funded the development of
the device and its initial testing at the Washington National
Primate Research Center. The promising results from those tests led
the U.S. Food and Drug Administration, in June, to approve the
device and the proposed surgical implantation procedure. Shortly
thereafter, the limited surgical trial in humans won approval from
the Western Institutional Review Board, an independent body charged
with protecting the safety of research subjects.
By basing their invention on cochlear implants whose design and
surgical implantation were already FDA-approved, Phillips and
Rubinstein leapfrogged scientists at other institutions who had
begun years earlier but chosen to develop novel prototypes.
“If you started from scratch, in a circumstance like this where
no one has ever treated a vestibular disorder with a device, it
probably would take 10 years to develop such a device,” Rubinstein
said.
The device epitomizes the translational advancements pursued at
UW’s academic medical centers, he said. He credited the team’s
skills and its access to the primate center, whose labs facilitated
the quick turnaround of results that helped win the FDA’s
support.
A successful human trial could lead the implant to become the
first-choice surgical intervention for Meniere’s patients, Phillips
said, and spark collaboration with other researchers who are
studying more widespread balance disorders.
The first patient will be a 56-year-old man from Yakima, Wash.
He has unilateral Meniere’s disease and has been a patient of
Rubinstein’s for about two years.
