Spinal cord stimulators tested as treatment for patients with migraine headaches

Wednesday 23 October 2013

Islamabad, Oct 24 (Newswire): Researchers at Rush University Medical Center are testing a new treatment for migraine headaches: occipital nerve stimulation, a surgical procedure in which an implanted neurostimulator delivers electrical impulses to nerves under the skin at the base of the head at the back of the neck.

This therapy may help migraine sufferers who do not respond to other available therapies, or who cannot tolerate the side effects of existing medications.

"The purpose of the randomized, double-blinded study is to evaluate the safety and efficacy of occipital nerve stimulation as a treatment for refractory migraine headache," says Dr. Sandeep Amin, Rush study investigator and anesthesiologist who surgically implants the device in the two-visit operation.

Rush is recruiting patients through the Diamond Headache Clinic and is the only site in Illinois in the trial.

The study, known as PRISM (Precision Implantable Stimulator for Migraine), uses Boston Scientific's Precision neurostimulator with approximately 150 patients at up to 15 sites in the U.S. The implantable pulse generator will deliver electrical impulses to the occipital nerves located just under the skin at the base of the skull at the back of the neck.

The Precision device is the smallest rechargeable neurostimulator on the market today and is already approved by the FDA for spinal cord stimulation to treat chronic pain.

There are more than 28 million migraine sufferers in the U.S., and up to 10 percent of these patients may not respond to existing treatments.

"Occipital nerve stimulation has the potential to provide relief to the large population of migraine sufferers who currently have no other medical treatments available to them that bring them relief," said Amin. "If effective, the implantable neurostimulator would provide a new treatment option to free these patients from their long-standing headache pain."

The smallest rechargeable neurostimulator available, the Precision device has been used in the treatment of more than 6,000 patients suffering from chronic pain, according to Boston Scientific.

The Precision neurostimulator is currently FDA approved for spinal cord to treat chronic pain by precisely delivering tiny electrical signals to the spinal cord that mask the perception of pain. Spinal cord stimulation is prescribed for patients with chronic pain in the limbs, trunk and back.

Migraine sufferers are monitored and complete a month-long pain diary as the first part of the study. Patients then undergo a two-part operation in which thin electrode leads are placed under the skin at the back of the neck.

A week later, the patient returns for the 45 minute procedure in which the neurostimulator is placed on one side in the lowest part of the back, and the leads are connected and the device activated. Patients then return to the neurologist for monitoring of their headaches.

During the first 3 months after the Precision neurostimulator is implanted, two different stimulation settings will be tried in different groups of patients. One group of patients is programmed to settings more likely to show a response, while the control group of patients is programmed to settings rather unlikely to be effective.

After the first three months, the control group of patients will have their devices programmed to the stimulation settings more likely to show a response.

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First implanted device to treat balance disorder developed

Islamabad, Oct 24 (Newswire): A University of Washington Medical Center patient on Thursday, Oct. 21, became 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.

See a related video at UW Medicine's YouTube site. Drs. Rubinstein and Phillips discuss the device: http://www.youtube.com/watch?v=iu047vTckvA

Cochlear Ltd. of Lane Cove, Australia, will manufacture the device. Cochlear is a medical equipment company and longtime maker of devices for hearing-impaired people.

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Younger brains are easier to rewire

Islamabad, Oct 24 (Newswire): A new paper from MIT neuroscientists, in collaboration with Alvaro Pascual-Leone at Beth Israel Deaconess Medical Center, offers evidence that it is easier to rewire the brain early in life.

The researchers found that a small part of the brain's visual cortex that processes motion became reorganized only in the brains of subjects who had been born blind, not those who became blind later in life.

The new findings, described in the journal Current Biology, shed light on how the brain wires itself during the first few years of life, and could help scientists understand how to optimize the brain's ability to be rewired later in life.

That could become increasingly important as medical advances make it possible for congenitally blind people to have their sight restored, said MIT postdoctoral associate Marina Bedny, lead author of the paper.

In the 1950s and '60s, scientists began to think that certain brain functions develop normally only if an individual is exposed to relevant information, such as language or visual information, within a specific time period early in life. After that, they theorized, the brain loses the ability to change in response to new input.

Animal studies supported this theory. For example, cats blindfolded during the first months of life are unable to see normally after the blindfolds are removed. Similar periods of blindfolding in adulthood have no effect on vision.

However, there have been indications in recent years that there is more wiggle room than previously thought, said Bedny, who works in the laboratory of MIT assistant professor Rebecca Saxe, also an author of the Current Biology paper. Many neuroscientists now support the idea of a period early in life after which it is difficult, but not impossible, to rewire the brain.

Bedny, Saxe and their colleagues wanted to determine if a part of the brain known as the middle temporal complex (MT/MST) can be rewired at any time or only early in life. They chose to study MT/MST in part because it is one of the most studied visual areas. In sighted people, the MT region is specialized for motion vision.

In the few rare cases where patients have lost MT function in both hemispheres of the brain, they were unable to sense motion in a visual scene. For example, if someone poured water into a glass, they would see only a standing, frozen stream of water.

Previous studies have shown that in blind people, MT is taken over by sound processing, but those studies didn't distinguish between people who became blind early and late in life.

In the new MIT study, the researchers studied three groups of subjects -- sighted, congenitally blind, and those who became blind later in life (age nine or older). Using functional magnetic resonance imaging (fMRI), they tested whether MT in these subjects responded to moving sounds -- for example, approaching footsteps.

The results were clear, said Bedny. MT reacted to moving sounds in congenitally blind people, but not in sighted people or people who became blind at a later age.

This suggests that in late-blind individuals, the visual input they received in early years allowed the MT complex to develop its typical visual function, and it couldn't be remade to process sound after the person lost sight. Congenitally blind people never received any visual input, so the region was taken over by auditory input after birth.

"We need to think of early life as a window of opportunity to shape how the brain works," said Bedny. "That's not to say that later experience can't alter things, but it's easier to get organized early on."

Bedny believes that by better understanding how the brain is wired early in life, scientists may be able to learn how to rewire it later in life. There are now very few cases of sight restoration, but if it becomes more common, scientists will need to figure out how to retrain the patient's brain so it can process the new visual input.

"The unresolved question is whether the brain can relearn, and how that learning differs in an adult brain versus a child's brain," said Bedny.

Bedny hopes to study the behavioral consequences of the MT switch in future studies. Those would include whether blind people have an advantage over sighted people in auditory motion processing, and if they have a disadvantage if sight is restored.

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