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Showing posts with label neurostimulation. Show all posts
Showing posts with label neurostimulation. Show all posts

Sunday, May 25, 2014

Can the Nervous System Be Hacked?

 

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Magazine |​NYT Now

Can the Nervous System Be Hacked?

By MICHAEL BEHARMAY 23, 2014

 

Mirela Mustacevic, who suffers from rheumatoid arthritis, had a nerve stimulator implanted as part of a medical trial. Her symptoms have lessened significantly. Credit Sarah Wong for The New York Times

 

One morning in May 1998, Kevin Tracey converted a room in his lab at the Feinstein Institute for Medical Research in Manhasset, N.Y., into a makeshift operating theater and then prepped his patient — a rat — for surgery. A neurosurgeon, and also Feinstein Institute’s president, Tracey had spent more than a decade searching for a link between nerves and the immune system. His work led him to hypothesize that stimulating the vagus nerve with electricity would alleviate harmful inflammation. “The vagus nerve is behind the artery where you feel your pulse,” he told me recently, pressing his right index finger to his neck.

The vagus nerve and its branches conduct nerve impulses — called action potentials — to every major organ. But communication between nerves and the immune system was considered impossible, according to the scientific consensus in 1998. Textbooks from the era taught, he said, “that the immune system was just cells floating around. Nerves don’t float anywhere. Nerves are fixed in tissues.” It would have been “inconceivable,” he added, to propose that nerves were directly interacting with immune cells.

 

‘There was nothing in the scientific thinking that said electricity would do anything. It was anathema to logic. Nobody thought it would work.’

Nonetheless, Tracey was certain that an interface existed, and that his rat would prove it. After anesthetizing the animal, Tracey cut an incision in its neck, using a surgical microscope to find his way around his patient’s anatomy. With a hand-held nerve stimulator, he delivered several one-second electrical pulses to the rat’s exposed vagus nerve. He stitched the cut closed and gave the rat a bacterial toxin known to promote the production of tumor necrosis factor, or T.N.F., a protein that triggers inflammation in animals, including humans.

“We let it sleep for an hour, then took blood tests,” he said. The bacterial toxin should have triggered rampant inflammation, but instead the production of tumor necrosis factor was blocked by 75 percent. “For me, it was a life-changing moment,” Tracey said. What he had demonstrated was that the nervous system was like a computer terminal through which you could deliver commands to stop a problem, like acute inflammation, before it starts, or repair a body after it gets sick. “All the information is coming and going as electrical signals,” Tracey said. For months, he’d been arguing with his staff, whose members considered this rat project of his harebrained. “Half of them were in the hallway betting against me,” Tracey said.

Inflammatory afflictions like rheumatoid arthritis and Crohn’s disease are currently treated with drugs — painkillers, steroids and what are known as biologics, or genetically engineered proteins. But such medicines, Tracey pointed out, are often expensive, hard to administer, variable in their efficacy and sometimes accompanied by lethal side effects. His work seemed to indicate that electricity delivered to the vagus nerve in just the right intensity and at precise intervals could reproduce a drug’s therapeutic — in this case, anti-inflammatory — reaction. His subsequent research would also show that it could do so more effectively and with minimal health risks.

Tracey’s efforts have helped establish what is now the growing field of bioelectronics. He has grand hopes for it. “I think this is the industry that will replace the drug industry,” he told me. Today researchers are creating implants that can communicate directly with the nervous system in order to try to fight everything from cancer to the common cold. “Our idea would be manipulating neural input to delay the progression of cancer,” says Paul Frenette, a stem-cell researcher at the Albert Einstein College of Medicine in the Bronx who discovered a link between the nervous system and prostate tumors.

“The list of T.N.F. diseases is long,” Tracey said. “So when we created SetPoint” — the start-up he founded in 2007 with a physician and researcher at Massachusetts General Hospital in Boston — “we had to figure out what we were going to treat.” They wanted to start with an illness that could be mitigated by blocking tumor necrosis factor and for which new therapies were desperately needed. Rheumatoid arthritis satisfied both criteria. It afflicts about 1 percent of the global population, causing chronic inflammation that erodes joints and eventually makes movement excruciating. And there is no cure for it.

In September 2011, SetPoint Medical began the world’s first clinical trial to treat rheumatoid-arthritis patients with an implantable nerve stimulator based on Tracey’s discoveries. According to Ralph Zitnik, SetPoint’s chief medical officer, of the 18 patients currently enrolled in the ongoing trial, two-thirds have improved. And some of them were feeling little or no pain just weeks after receiving the implant; the swelling in their joints has disappeared. “We took Kevin’s concept that he worked on for 10 years and made it a reality for people in a real clinical trial,” he says.

Conceptually, bioelectronics is straightforward: Get the nervous system to tell the body to heal itself. But of course it’s not that simple. “What we’re trying to do here is completely novel,” says Pedro Irazoqui, a professor of biomedical engineering at Purdue University, where he’s investigating bioelectronic therapies for epilepsy. Jay Pasricha, a professor of medicine and neurosciences at Johns Hopkins University who studies how nerve signals affect obesity, diabetes and gastrointestinal-motility disorders, among other digestive diseases, says, “What we’re doing today is like the precursor to the Model T.”

The biggest challenge is interpreting the conversation between the body’s organs and its nervous system, according to Kris Famm, who runs the newly formed Bioelectronics R. & D. Unit at GlaxoSmithKline, the world’s seventh-largest pharmaceutical company. “No one has really tried to speak the electrical language of the body,” he says. Another obstacle is building small implants, some of them as tiny as a cubic millimeter, robust enough to run powerful microprocessors. Should scientists succeed and bioelectronics become widely adopted, millions of people could one day be walking around with networked computers hooked up to their nervous systems. And that prospect highlights yet another concern the nascent industry will have to confront: the possibility of malignant hacking. As Anand Raghunathan, a professor of electrical and computer engineering at Purdue, puts it, bioelectronics “gives me a remote control to someone’s body.”

Despite the uncertainties, in August, GlaxoSmithKline invested $5 million in SetPoint, and its bioelectronics R. & D. unit now has partnerships with 26 independent research groups in six countries. Glaxo has also established a $50 million fund to support the science of bioelectronics and is offering a prize of $1 million to the first team that can develop an implantable device that can, by recording and responding to an organ’s electrical signals, exert influence over its function. Instead of drugs, “the treatment is a pattern of electrical impulses,” Famm says. “The information is the treatment.” In addition to rheumatoid arthritis, Famm believes, bioelectronic medicine might someday treat hypertension, asthma, diabetes, epilepsy, infertility, obesity and cancer. “This is not a one-trick pony.”

Kevin Tracey, who is 56, came to bioelectronics because of two significant deaths. The first occurred when he was in preschool. He was 5 when his mother died as a result of an inoperable brain tumor. Shortly after the funeral­, Tracey found his maternal grandfather, a professor of pediatrics at Yale, alone in his den. “I climbed onto his lap and asked what happened,” Tracey says. “He explained that surgeons tried to take it out but couldn’t separate the brain-tumor tissue from the normal neurons. I remember saying to him, ‘Somebody should do something about that.’ That was when I decided to be a neurosurgeon. I wanted to solve problems that were insolvable.”

Tracey’s second formative experience took place in May 1985. Having trained for neurosurgery at Cornell, he was on rotation for his residency in the emergency room at New York Hospital when an 11-month-old baby girl named Janice arrived in an ambulance with burns covering 75 percent of her body. Her grandmother was cooking when she tripped and doused Janice with a pot of boiling noodles. After three weeks in the burn unit recovering from skin grafts, Janice appeared to stabilize. Tracey joined Janice’s family to celebrate her first birthday in her hospital room. Janice was upbeat, smiling and giggling. The next day, she was dead.

“I was haunted by her case,” Tracey says. When the autopsy report was inconclusive, Tracey redirected his energy into medical research, specifically inflammation related to sepsis, which he believed contributed to Janice’s unexpected death. Sepsis occurs when the immune system goes into overdrive, producing a potentially lethal inflammatory response to fight a severe infection. At the time of her death, however, Janice did not have an infection. It took another year to figure out that it was an overproduction of tumor necrosis factor — the catalyst for inflammation — that caused Janice’s septic shock, though her death remains a mystery.

Kevin Tracey, a neurosurgeon, studies the effects of stimulating nerves with electricity to fight disease. Credit Katherine Wolkoff for The New York Times

“Her brakes had failed,” Tracey says. “She made too much T.N.F. The obvious question was, why?” He credits Linda Watkins, a neuroscientist at the University of Colorado, Boulder, for furnishing the pivotal clue. In the mid-1990s, Watkins was exploring possible neural connections between the brain and the immune system in rats by injecting them with cytokines — molecules that, like tumor necrosis factor, contribute to inflammation — to cause fevers. But when she cut their vagus nerves, the fever never materialized. Watkins concluded that the vagus nerve must be the conduit through which the body signals the brain to induce fever.

Tracey followed her lead by giving mice a toxin known to cause inflammation and then dosing them with an anti-inflammatory drug he had been investigating. “We injected it into their brains in teeny amounts, too small to get into their bloodstream,” he says. The drug did what it was supposed to do: It halted the production of tumor necrosis factor in the brain. Surprisingly, it also halted the production of tumor necrosis factor in the rest of the body. When Tracey cut the vagus nerve, however, the drug had no effect in the body.

“That was the eureka moment,” he says. The signal generated by the drug had to be traveling from the brain through the nerve because cutting it blocked the signal. “There could be no other explanation.”

Tracey then wondered if he could eliminate the drug altogether and use the nerve as a means of speaking directly to the immune system. “But there was nothing in the scientific thinking that said electricity would do anything. It was anathema to logic. Nobody thought it would work.”

After that first surgery on the rat in 1998, Tracey spent 11 years mapping the neural pathways of tumor-necrosis-factor inflammation, charting a route from the vagus nerve to the spleen to the bloodstream and eventually to mitochondria inside cells. “We now know more about this electrical circuit to treat [inflammation] than is known about some clinically approved drugs,” Tracey says.

By 2009, SetPoint felt ready to test Tracey’s work on people with rheumatoid arthritis, and Ralph Zitnik was approached about joining the company. “It was nuts,” Zitnik told me. “Sticking something on the vagus nerve to take away R.A.? People would think it’s witchcraft.” Zitnik’s background was in pharmaceuticals; at Amgen, he contributed to the development of Enbrel, a rheumatoid-arthritis drug that had $4.7 billion in sales last year, which made it No. 7 on the industry’s best-seller list. But the more he talked with Tracey and pored over the research, the more he said to himself: “There is good science behind this. I thought, This could work.”

 

SHOCK TREATMENT - VAGUS NERVE IMPLANT POD MAY 20, 2014 Illustration by Clint Ford

During a 20-minute operation, a neuVAGUS NERVE IMPLANT POD MAY 20, 2014 Illustration by Clint Fordrosurgeon will slide SetPoint Medical’s bioelectronic implant onto the vagus nerve on the left side of a patient’s neck, and then snap on an outer housing called the Pod to hold the device in place. Once the implant is activated, electrical impulses transmitted from the implant will communicate directly with immune cells in the spleen and the gastrointestinal tract, inducing them to reduce the production of cytokines — molecules that are involved in inflammation. To recharge the device’s batteries and update its software, patients and physicians will use an iPad app to control a wearable collar that transmits power and data wirelessly through the skin.

 

 

Zitnik’s first task at SetPoint was to recruit a lead scientist to set up a clinical trial. Many scientists in the United States and Europe were hesitant to do it, he says, but eventually he hired Paul-Peter Tak, a well-regarded immunologist and rheumatologist based at the Academic Medical Center, the University of Amsterdam’s teaching hospital. “He was a forward-thinking person willing to try an unconventional approach like this,” Zitnik says. Tak in turn hired Frieda Koopman, who was working on her Ph.D. in rheumatology at A.M.C., to find potential patients in the Netherlands and elsewhere in Europe.

The day after an article about the planned trial appeared in a Dutch newspaper, Koopman’s office got more than a thousand calls from rheumatoid-arthritis patients begging to participate. “We never saw that coming,” Koopman says. “We thought we might get one or two patients to join, and wouldn’t that be nice.” Invasive surgery was involved, after all. Koopman’s team returned almost every call and selected several subjects based on what medications they had tried and the severity of the pain and swelling in their joints. Over the next two years, her team continued to enroll new patients.

The subjects in the trial each underwent a 45-minute operation. A neurosurgeon fixed an inchlong device shaped like a corkscrew to the vagus nerve on the left side of the neck, and then embedded just below the collarbone a silver-dollar-size “pulse generator” that contained a battery and microprocessor programmed to discharge mild shocks from two electrodes. A thin wire made of a platinum alloy connected the two components beneath the skin. Once the implant was turned on, its preprogrammed charge — about one milliamp; a small LED consumes 10 times more electricity — zapped the vagus nerve in 60-second bursts, up to four times a day. Typically, a patient’s throat felt constricted and tingly for a moment. After a week or two, arthritic pain began to subside. Swollen joints shrank, and blood tests that checked for inflammatory markers usually showed striking declines.

Koopman told me about a 38-year-old trial patient named Mirela Mustacevic whose rheumatoid arthritis was diagnosed when she was 22, and who had since tried nine different medications, including two she had to self-inject. Some of them helped but had nasty side effects, like nausea and skin rashes. Before getting the SetPoint implant in April 2013, she could barely grasp a pencil; now she’s riding her bicycle to the Dutch coast, a near-20-mile round trip from her home. Mustacevic told me: “After the implant, I started to do things I hadn’t done in years — like taking long walks or just putting clothes on in the morning without help. I was ecstatic. When they told me about the surgery, I was a bit worried, because what if something went wrong? I had to think about whether it was worth it. But it was worth it. I got my life back.”

In February, I met Moncef Slaoui, Glaxo’s chairman of Global Research and Development, at one of the company’s 16 facilities he oversees worldwide, this one in King of Prussia, Pa. Slaoui, who is 55 and has a Ph.D. in molecular biology and immunology, was instrumental in developing the first malaria vaccine and is considered one of the most influential executives in the pharmaceutical industry.

“When Kris came to me in early 2012 with this idea of vagus nerve stimulation,” Slaoui told me, “I was like: C’mon? You’re gonna give a shock and it changes the immune system? I was very skeptical. But finally I agreed to visit Kevin’s lab. I wanted the data, the evidence. I don’t like hot air.” He went to Tak, the lead scientist for the trials. “I asked him, ‘Paul-Peter, is it really real?’ ”

 

SetPoint Medical’s new neural implant (currently being tested on animals). Credit Katherine Wolkoff for The New York Times

After getting an endorsement from Tak, who is now Glaxo’s global head of immuno-inflammation research, Slaoui committed to financing SetPoint. The investment was modest, though, because he felt that Tracey’s device was “just a starting point. It was still very broad — you touch the vagus nerve, you touch most of your viscera. We had wanted something very specific.” What he didn’t want was “the bulldozer approach” that characterizes already existing stimulators for treating Parkinson’s, chronic pain and epilepsy. (Pacemakers differ because they stimulate muscle, not nerves.) These devices are indiscriminate, blasting electricity into billions of neurons and hoping for the best. As Slaoui saw it, SetPoint’s stimulator was a primitive forerunner to “a device that reads your electrical impulses and sees when something is wrong, then corrects what needs correcting.”

In 2006, Slaoui continued, “when I became chairman of R. & D., R. & D. was a liability to this company. We were spending lots of money and not producing new molecules for new medicines. I had to acknowledge that the current way of doing R. & D. wasn’t likely to be successful.” Four years later, Slaoui put together a 14-member think tank and discussed, among other topics, the Human Brain Project. The multinational endeavor, directed by the neuroscientist and Fulbright scholar Henry Markram, at the Swiss Federal Institute of Technology in Lausanne, is trying to create a computer simulation of the human brain. That got Slaoui “thinking about electrical signaling, an opportunity to make medicine — a therapeutic intervention — that’s super highly specific in terms of its geographic position. I’m going to go to the nerve that goes to your kidney and nowhere else, and only to your left kidney, and to a particular area of the left kidney.”

That degree of precision would address one of Slaoui’s major criticisms of conventional drugs: They flood the body, and then doctors have to hope that they will perform only where they’re supposed to. “It is really difficult to design a molecule that will only interact where you want it, because it goes everywhere.” The upshot, usually: side effects. Bioelectronics could potentially eliminate those, as well as the costly redundancy involved in the drug-discovery process, in which every promising molecule must be independently evaluated. “There is very little that is transposable from one molecule to the next,” Slaoui said. “You have to redo everything.” Bioelectronics attracted him, he says, because “95 percent of the hardware is the same,” no matter what disease it treats.

So Slaoui found himself working for a drug company while devoting himself to the idea of treating illness without drugs. In July 2012, he and Famm toured Markram’s facilities in Lausanne. There Markram showed them a 3-D digital visualization on a giant screen of 100,000 synapses actively firing in a mouse brain.

At that moment, Famm says, he and Slaoui realized they were “biting off too much.” Slaoui and Famm concluded that starting with the brain — which seemed logical, given that it’s the body’s C.P.U. — could take decades to yield viable treatments. The human brain’s circuitry, with 100 billion neurons, seemed far too complex. “Why don’t we just skip the brain and go straight to the organs?” Slaoui suggested.

Right then, Slaoui said, “we decided to focus on the peripheral nervous system.” The peripheral nerves link the brain and spinal cord (the central nervous system) to the organs and limbs. Rather than try to fathom the brain — a black box, basically, with its 100 trillion neural connections — Slaoui proposed that they put “an interface between a nerve and the organ with an electrical device.” To eavesdrop on a telephone call, his thinking went, you don’t tap into the switching center and search for the conversation. You go to the line nearest the caller’s location. Compared with the brain, the cablelike bundles that are the peripheral nerves contain vastly fewer fibers — hundreds versus billions.

 

The brain, with its billions of neurons, seemed far too complex. ‘Why don't we just skip the brain and go straight to the organs?’ someone suggested.

When I joined Famm in Philadelphia in February, he referred to his role as Glaxo’s bioelectronics chief as “like being a missionary.” Famm, who lives in London, was in the U.S. to attend half a dozen meetings with bioelectronics researchers. His challenge is coaxing those from disparate disciplines to embrace a singular vision. Whereas drug discovery primarily involves like-minded thinkers — molecular biologists, chemists, geneticists — bioelectronics calls for alliances between experts in fields that in many cases have little to do with medicine — nanotech, optics, electrical engineering, materials science, computer programming, wireless networking and data mining. At the moment, Famm is focused on getting what he called a “transdisciplinary” group of scientists to agree on how to solve two key technical challenges.

The first is shrinking the hardware. It must be small enough to attach to virtually any nerve yet still have enough battery power and circuitry to run algorithms that generate the patterns of electrical impulses needed to treat various diseases. At the Charles Stark Draper Laboratory in Cambridge, Mass., we met with a team working on miniaturization. Draper is best known for internal navigation systems that guide things like ballistic missiles and spaceships. Bryan McLaughlin, who directs bioelectronics development at Draper, showed me the latest prototype mock-up — a dime-size implant. It’s small, he said, but not nearly small enough. McLaughlin wants to get its electrodes, microprocessor, battery and a wireless transmitter into a device no larger than a jelly bean. “It’s also important to make it closed-loop, with the ability to read and write to the nervous system.” The goal, in other words, is to end up with something that can continuously monitor a patient and then dispense bioelectronic therapy as needed.

The second challenge is devising a method to make sense of signals emanating simultaneously from hundreds of thousands of neurons. Accurate recording and analysis are essential to bioelectronics in order for researchers to identify the discrepancies between baseline neural signals in healthy individuals and those produced by someone with a particular disease. The conventional approach to recording neural signals is to use tiny probes with electrodes inside called patch clamps. A prostate-cancer researcher, for example, could attach patch clamps to a nerve linked to the prostate in a healthy mouse and record the activity. The same thing would be done with a mouse whose prostate had been genetically engineered to produce malignant tumors. Comparing the output from both might allow the researcher to determine how the neural signals differ in cancerous mice. From such data, a corrective signal could be programmed into a bioelectronic device to treat the cancer.

using patch clamps. They can sample only one cell’s activity at a time, and therefore fail to gather enough data to see the big picture. As Adam E. Cohen, who teaches chemistry and physics at Harvard, puts it, “It’s like trying to watch an opera through a straw.”

Cohen, an expert in an emerging field called optogenetics, thinks he can overcome the limitations of the patch clamps. His research is trying to use optogenetics to decipher the neural language of disease. “Getting patch clamps into a single [neuron] is extremely slow and laborious — about an hour per cell,” Cohen told me when I visited his lab recently. “The bigger problem is that [neural] activity comes not from the voices of individual neurons but from a whole orchestra of them acting in relation to each other. Poking at one at a time doesn’t give you the global view.”

Optogenetics arose out of a series of developments in the 1990s. Scientists knew that proteins, called opsins, in bacteria and algae generated electricity when exposed to light. Optogenetics exploits this mechanism. Opsin genes are inserted into the DNA of a harmless virus, which is then injected into the brain or a peripheral nerve of a test subject. By choosing a virus that prefers some cell types over others, or by altering the virus’s genetic sequence, researchers can target specific neurons — cold- or pain-sensing, for example — or regions of the brain known to be responsible for certain actions or behaviors. Next, an optical fiber — a spaghetti-thin glass cable that transmits light from its tip — is inserted through the skin or skull to the site of the virus. The fiber’s light activates the opsin, which in turn conducts an electrical charge that forces the neuron to fire. Researchers have already controlled mouse behavior with optogenetics — inducing sleep and aggression on command.

 

Instead of drugs, says the man who runs GlaxoSmithKline's bioelectronics research and development, ‘the treatment is a pattern of electrical impulses. The information is the treatment.’

Before opsins can be used to activate neurons involved in specific ailments, however, scientists must determine not only which neurons are responsible for a particular disease but also how that disease communicates with the nervous system. Like computers, neurons speak a binary language, with a vocabulary based on whether their signal is on or off. The specific sequence, interval and intensity of these on-off shifts determine how information is conveyed. But if each disease can be thought of as speaking its own language, then a translator is needed. What Cohen and others recognized was that optogenetics can do that job. So Cohen reverse-engineered the process: Instead of using light to activate neurons, he used light to record their activity.

Cohen showed me his “Optopatch” machine. It consisted of red and blue lasers, mirrors, lenses, a high-speed digital camera, a video projector, a microscope and several quiet cooling fans. After he turned it on, a postdoc fellow who works in his lab, Shan Lou, inserted a petri dish under its microscope. The dish contained 11 live neural cells from mice, harvested from dorsal-root ganglia, which relay sensory input to the brain. Lou added a few drops of capsaicin extract, the irritant in pepper spray, and then turned the camera on for 14 seconds. In that brief period, it snapped 7,000 frames, totaling 12 gigabytes of data. To analyze it, Cohen had written software that searches for patterns by employing techniques developed for digital voice and face recognition. “We also use algorithms and optical tricks derived from astrophysics,” Cohen said. Seconds later, an analysis appeared on Lou’s computer screen. Three of the 11 cells had been identified as firing in response to the capsaicin, indicating that they were pain-sensing neurons. It would have taken Cohen more than a day to record and make sense of that cellular information with a patch clamp. This sort of effort was a step, he said, “toward imaging large numbers of neurons in parallel, hundreds, perhaps thousands.”

Cohen is collaborating with Ed Boyden, a professor of neuroscience at M.I.T. and a pioneer in optogenetics, to develop the so-called closed-loop implant envisioned by Bryan McLaughlin at Draper Labs. Optogenetics, Boyden told me, enables him to “aim light at some subset of cells [without] activating all the stray cells nearby.”

Opsins might point the way to future treatments for all kinds of diseases, but researchers will most likely have to develop bioelectronic devices that don’t use them. Using genetically engineered viruses is going to be tough to get past the F.D.A. The opsin technique hinges on gene therapy, which has had limited success in clinical trials, is very expensive and seems to come with grave health risks.

Cohen mentions two alternatives. One involves molecules that behave like opsins; another uses RNA that converts into an opsinlike protein — because it doesn’t alter DNA, it doesn’t have the risks associated with gene therapy. Neither approach is very far along, however. And “you still face the problem of getting the light in,” he says. Boyden is developing a brain implant with a built-in laser, but Cohen believes an external light source is more likely for most bioelectronics applications.

Surmounting these sorts of technical hurdles “might take 10 years,” Famm figures. That seems somewhat optimistic if you consider Glaxo’s investment so far in bioelectronics. Melinda Stubbee, the company’s director of communications, says it has spent roughly $60 million in the area, a pittance compared with its $6.5 billion in total R. & D. expenditures in 2013. Slaoui, defending the number, said, “Funding of R. & D. is like an investment” — money only flows toward bankable ideas. While he thinks the area shows promise, he seems to want independent researchers to do the legwork before Glaxo buys in further.

 

‘I think this is the industry that will replace the drug industry,’ says a pioneer in bioelectronics.

At one point, Famm referred to detractors who say bioelectronics is “too risky, will take too long and is maybe even a bit bonkers.” In trying to find some of them, I contacted a number of financial analysts who track Glaxo and the pharmaceutical industry. One, Mark Clark, at Deutsche Bank, said to me in an email: “I know next to nothing about this early-stage technology! I am prepared to bet you will not find a single Glaxo analyst that knows anything about this! Research technologies were a vogue thing to be expert on in the ’90s and tech-bubble years, but we only care about drugs that are actually in the clinical pipeline these days, not how they get there — to be brutally blunt!”

In short, the fledgling bioelectronics industry is nowhere near mature enough for analysts to make meaningful estimates about its revenue potential. But people like Clark will certainly begin paying closer attention if bioelectronics starts to capture even a sliver of the lucrative pharmaceutical market. Drug sales for rheumatoid arthritis alone were $12.3 billion in 2012. That looks like a big opportunity to an outfit like SetPoint.

Yet if large numbers of patients someday choose bioelectronics over drugs, another issue awaits resolution: security. Bioelectronics devices will feature wireless connectivity so they can be fine-tuned and upgraded, “just like the software on your iPhone,” Famm says. And wireless means hackable, an unsettling fact that worries two experts on medical-device security: Niraj Jha, a professor of electrical engineering at Princeton University, and Anand Raghunathan, who runs the Integrated Systems Laboratory at Purdue.

Fears of medical devices being hacked aren’t new. In 2007, Dick Cheney’s cardiologist disabled the wireless functionality in the former vice president’s defibrillator to prevent terrorists from trying to stop his heart. Jha and Raghunathan, along with the lead author, Chunxiao Li, detailed how this might be accomplished in a seven-page paper they wrote, “Hijacking an Insulin Pump,” published in June 2011. The paper described a hack they performed in their lab using inexpensive, off-the-shelf hardware.

According to Jha and Raghunathan, there are no known cases of malicious attacks on medical devices. Nevertheless, Raghunathan says, “Society should be warned about these possibilities.” The Department of Homeland Security is no doubt worried, addressing the potential threat in an alert it issued last June. In August, the F.D.A. offered guidelines to medical-device manufacturers, recommending “wireless protection” to reduce “risks to patients from a security breach.” Whether bioelectronics developers do anything to thwart hacking (the F.D.A. guidelines are not mandatory) may ultimately depend on whether Jha and Raghunathan’s fears are realized.

Draper’s McLaughlin doesn’t dismiss these concerns but notes that there is no “incentive for device companies to do anything about security.” He adds: “Nobody has been sued. No patient has died. But the first event that occurs with one of these devices — companies will jump on it and create secure platforms.”

SetPoint’s chief technology officer is Mike Faltys, a medical engineer who was integral to designing the modern cochlear implant. Faltys worked for six years out of his garage, first re-engineering an existing electrical stimulator, used to stop seizures, that became the device implanted in patients in SetPoint’s trial, and more recently finishing a significantly more advanced implantable unit that he calls “the microregulator.”

Housed in a pod shaped like a hot-dog bun and the size of a multivitamin, the entire microregulator is entirely self-contained — onboard battery, microprocessor and electrodes are integrated into a single unit. It can be wirelessly recharged, and adjusted and updated with an iPad app. The surgery to clamp it onto the vagus nerve will take about 20 minutes, and once in place, it will provide pain relief to a rheumatoid-arthritis patient for a decade or more before it needs servicing.

On one occasion during my travels with Famm, I got to hold SetPoint’s newfangled microregulator. For now, it’s only capable of transmitting very crude signals to communicate with the nervous system — more like grunts and groans rather than the precise vocabulary that Slaoui envisions for bioelectronic therapies. Even so, the microregulator felt elegant and powerful and promising in my palm. “A patient gets a device like this implanted once for one disease, and they’re done,” Tracey says. “No prescriptions, no medicines, no injections. That’s the future. That’s what gets me out of bed in the morning.”

Michael Behar writes about science and the environment. His work has appeared in “The Best American Travel Writing” and “The Best American Science and Nature Writing.”

http://www.nytimes.com/2014/05/25/magazine/can-the-nervous-system-be-hacked.html?emc=eta1&_r=0

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Saturday, November 3, 2012

Neurostimulation-past, present, and beyond.

2012 Sep;12(5):188-91. doi: 10.5698/1535-7511-12.5.188.

Neurostimulation-past, present, and beyond.

Source

Institution of Clinical Neuroscience and Physiology, Sahlgrenska Academy, Göteborgs University, 413 45 Göteborg, Sweden, ebm@neuor.gu.se.

Abstract

Neurostimulation as a treatment for epilepsy has been around for almost 20 years in the form of vagus nerve stimulation. Newer types of neurostimulation are being developed and stand on the brink of approval for use. The two newest therapies, not yet approved in the United States, are deep brain stimulation and the Responsive Neurostimulator System . In fact, in Europe, approval has already been given for deep brain stimulation and newer forms of vagus nerve stimulation. Efficacy is similar between these therapies, and side effects are moderate, so what will be the future? The challenge will be to learn how to use these therapies correctly and offer the right treatment for the right patient.
PMID:
23118604
[PubMed - in process]

http://www.ncbi.nlm.nih.gov/pubmed/23118604

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Tuesday, August 7, 2012

Markets for Electrostimulation Devices (Neurostimulation, Cardiac Rhythm Management, Fracture Healing and Others)

sacbee.com

This story is taken from Sacbee /

Markets for Electrostimulation Devices (Neurostimulation, Cardiac Rhythm Management, Fracture Healing and Others)

Published Monday, Aug. 06, 2012


/PRNewswire/ -- Reportlinker.com announces that a new market research report is available in its catalogue:
Markets for Electrostimulation Devices (Neurostimulation, Cardiac Rhythm Management, Fracture Healing and Others)
http://www.reportlinker.com/p0944033/Markets-for-Electrostimulation-Devices-Neurostimulation-Cardiac-Rhythm-Management-Fracture-Healing-and-Others.html#utm_source=prnewswire&utm_medium=pr&utm_campaign=Cardiovascular_Devices
Electrical and magnetic stimulation is the primary focus of this Kalorama Information Report. Rather than attempting to define and classify all of the varying electrostimulatory methods, this report groups technologies into basic categories based on application and complexity.
The audience for this report includes technical directors, business development managers, investors, and analysts who want a panoramic view, at a quantitative level, of the technology and medical applications of electrical and magnetic stimulation. This is a far-reaching field, and this report thus serves as a survey aimed at providing insight about the realm of market possibilities. Two general segments are discussed with various sub-segments included:
External Electrical Stimulation Devices:
  • Bone Growth Simulation

  • Transcutaneous Electrical Nerve Stimulation (TENS)

  • Ultrasound-Accelerated Fracture Healing

Implanted Electrical Simulation Devices
  • Bone Growth Stimulation

  • Cardiac Resynchronization Therapy

  • Deep Brain Stimulation

  • Gastric Electrical Stimulation

  • Implantable Cardiac Pacemakers

  • ImplantableCardioverter-Defibrillators

  • Sacral Nerve Stimulation

  • Spinal Cord Stimulation

  • Vagus Nerve Stimulation

Companies involved in the market are profiled to provide an understanding of today's competitive environment and marketing strategies.
Demand for both electrical and magnetic neurostimulationtechnologies is expected to grow moderately during the next few years.
TENS is commonly used for pain management.Despite controversy over the degree to which TENS is more effective than placebo in reducing pain, the market for TENS equipment continues to remain steady. Electromuscular stimulation (EMS) of muscle tissue can aid in the recuperation of overworked muscles. Technological progress continues in EMS,especially with microprocessors that allow protection against the risk of burning and elimination of electrical pain. Transcranial magnetic stimulation (TMS) is a non-invasive technique that uses an electromagnet placed on the patient's scalp to alter brain activity. Repetitive TMS (rTMS), which uses varying frequencies and intensities of magnetic fields, seems to have therapeutic value. During the previous years, rTMS has received a growing attention in the popular and scientific media. The market forecasts reflect growing professional medical acceptance. The demand of electrostimulation products based on external electrodes is expected to benefit from innovative developments in FES designed to augment movement of atrophied muscles, promote new nerve function, and provide interfaces between nerve cells and computing devices. The market for treating depression is one of the most promising applications of neurotechnology devices. The potential market opportunity is huge, with between over 20 million people in the U.S.alone who could potentially benefit.
A new group of active electrodes are underdevelopment. These can connect nerve cells to microcircuits and provide a living link between living tissues and hardware. Direct interfaces between small networks of nerve cells and microdevices are advancing the understanding of nerves and leading the way to a new generation of hybrid devices that communicate between computers and biological neural networks. There are several research teams in the U.S.and Europe that are currently working on so-called neural-silicon hybrid chips. Wireless technology could lead to the replacement of leads with small radios that can transmit and receive information and energy.
CHAPTER ONE: EXECUTIVE SUMMARY
  • Electrostimulation and Neuroprosthetic Technology Introduction

  • Scope of This Report

  • A Strong Market Foundation

  • Future Directions

  • Market Size and Projections

CHAPTER TWO: INTRODUCTION TO ELECTROSTIMULATION AND RELATED TECHNOLOGIES
  • Stimulation Therapeutics for Muscles and Nerves

  • Medical Applications of External Electrode Modalities

    • Electrical Stimulation

    • Measurement and Diagnosis

    • Stimulation by Magnetic Field Pulses

    • Ultrasonic and Short Wavelength Diathermy

  • Medical Applications of Implanted Electrode Modalities

    • Bladder Stimulators

    • Carotid Sinus Nerve Stimulation

    • Cochlear Implant

    • Deep Brain Stimulation

    • Electrical Continence

    • Electrical Nerve Stimulation

    • Pelvic Floor Stimulation

    • Phrenic Nerve Stimulation

    • Sacral Nerve Stimulation

    • Spinal Cord Stimulation

    • Vagus Nerve Stimulation

  • Characteristics of the Electrostimulation Market

    • Market Segmentation of Neurostimulation Modalities

  • Market Trends and Assumptions

  • Competitive Landscape and Issues

    • Applicable Industrial and Regulatory Codes

    • Companies in the Electrostimulation Market

  • End-User Segments

CHAPTER THREE : EXTERNAL ELECTRICAL STIMULATION DEVICES
  • Introduction

  • External Electrostimulation Technologies

  • Bone Growth Stimulation

    • Market Analysis

  • EMS, NMS, TENS

    • Transcutaneous Electrical Nerve Stimulation (TENS)

    • Early Observations of Pain Relief

    • Physiological Model Theories

    • Interferential Current

    • Galvanic Stimulation

    • Electrodes

    • Market Analysis

  • Ultrasound-Accelerated Fracture Healing

    • Market Analysis

  • Other Treatments

    • ECT

    • TMS and rTMS

  • Market Forecasts for Electrostimulation With External Electrodes

CHAPTER FOUR: IMPLANTED ELECTRICAL AND NEUROLOGICAL STIMULATION DEVICES
  • Introduction

  • Types of Implanted Electrode Systems

  • Implanted Bone Growth Stimulators

    • Market Analysis

  • Cardiac Rhythm Management

    • Cardiac Resynchronization Therapy

    • Implantable Cardiac Pacemakers

    • Implantable Cardioverter-Defibrillators

    • Market Analysis

  • Spinal Cord Stimulation (SCS)

    • Basic Implementation

    • SCS vs TENS in Pain Relief

    • Cost-Benefit Analysis of SCS

    • Market Analysis

  • Sacral Nerve Stimulation (SNS)

    • Control of Urinary Incontinence

    • Control of Fecal Incontinence

    • Market Analysis

  • Vagus Nerve Stimulation (VNS)

    • Seizure Control in Epilepsy

    • Treatment of Depression

    • Market Analysis

  • Deep Brain Stimulation (DBS)

    • Treatment of Neurological Movement Disorders

    • Market Analysis

  • Gastric Electrical Stimulation (GES)

    • Market Analysis

  • Market Analysis for Implanted Electrical and Neurological Stimulation Devices

CHAPTER FIVE: INDUSTRY TRENDS AND ISSUES
  • New Innovations

    • Brain Stimulation

    • Obstructive Sleep Apnea

    • Neurostim and Obesity

    • Implantable Therapy for Resistant Hypertension

    • Pain Therapy

    • Epilepsy

  • New Developments and Alternative Technologies

    • Magnetic Stimulation

    • Transcranial Magnetic Stimulation (TMS)

    • Magnetic Stimulation and Depression Treatment

    • Magnetic Stimulation and Neurological Trauma Therapy

    • Magnetic Stimulation and Auditory Hallucinations

    • Magnetic Stimulation and the Effects on Cerebral Blood Flow

    • TMS Potential

    • TMS/rTMS Instrument Parameters

    • Neuroprosthetics

    • Functional Electrical Stimulation (FES)

    • Bidirectional Neuroprotheses

    • Cochlear Implants

    • Retinal Implants

    • Neurostimulation for Depression

    • The Neuron–Silicon Interface

    • Physiology of EMS Applications

      • Endurance Training by Increased Oxygen Supply

      • Muscle Recovery via Increased Blood Flow

    • Muscle Diagnostics with Electromyography

    • Uncertainties in Electrostimulation Business Development Management

    • Future advancements

    • New technology challenges

CHAPTER SIX: MARKET SUMMARY
  • Total Market Overview

  • Geographical Market Analysis

CHAPTER SEVEN: COMPANY PROFILES
LIST OF EXHIBITS
CHAPTER ONE: EXECUTIVE SUMMARY
    • Summary Table: Electrical and Neurostimulation Equipment/Device Market by Application Method, 2010-2017

    • Summary Figure: Electrical and Neurostimulation Equipment/Device Market by Application Method, 2010-2017

CHAPTER TWO: INTRODUCTION TO ELECTROSTIMULATION AND RELATED TECHNOLOGIES
    • Table 2-1: Energy/Radiation Stimulation Medical Electronics Products

    • Table 2-2: Implanted Electrode Stimulation Technologies

    • Table 2-3: Market Drivers Impacting Electrostimulation Equipment Sales

    • Table 2-4: Market Restraints Limiting Electrostimulation Equipment Sales

    • Table 2-5: Standard Industrial Codes (SIC) for Electrical/Magnetic Stimulation Equipment

    • Table 2-6: North American Industry Classification System (NAICS) Codes for Electrical/Magnetic Stimulation Equipment

    • Table 2-7: Major Players by Segment, 2012

    • Table 2-8: US Healthcare Practitioners by Occupation Title, 2010

CHAPTER THREE: EXTERNAL ELECTRICAL STIMULATION DEVICES
    • Table 3-1: Electrode Stimulation Modalities with External Electrodes Type and Description

    • Table 3-2The World Market for External Bone Growth Stimulation Devices 2010-2017

    • Figure 3-1: The World Market for External Bone Growth Stimulation Devices 2010-2017

    • Table 3-3: TENS and EMS Stimulation Modes

    • Table 3-4: The World Market for TENS and EMS Devices 2010-2017

    • Figure 3-2: The World Market for TENS and EMS Devices 2010-2017

    • Table 3-5: The World Market for Ultrasound-Accelerated Fracture Healing Systems 2010-2017

    • Figure 3-3: The World Market for Ultrasound-Accelerated Fracture Healing Systems 2010-2017

    • Table 3-6: The World Market for Other External Electrostimulation Devices 2010-2017

    • Figure 3-4: The World Market for Other External Electrostimulation Devices 2010-2017

    • Table 3-7: External Electrostimulation Device Market by Product Type 2010-2017

    • Figure 3-5: External Electrostimulation Device Market by Product Type 2010-2017

    • Figure 3-6: External Electrostimulation Device Market by Product Type 2012 and 2017

CHAPTER FOUR: IMPLANTED ELECTRICAL AND NEUROLOGICAL STIMULATION DEVICES
    • Table 4-1: The World Market for Implantable Bone Growth Stimulation Devices 2010-2017

    • Figure 4-1: The World Market for Implantable Bone Growth Stimulation Devices 2010-2017

    • Table 4-2: The World Market for Implantable Cardiac Rhythm Management Devices 2010-2017

    • Figure 4-1: The World Market for Implantable Cardiac Rhythm Management Devices 2010-2017

    • Table 4-3: The World Market for Spinal Cord Stimulation Devices 2010-2017

    • Figure 4-2: The World Market for Spinal Cord Stimulation Devices 2010-2017

    • Table 4-4: The World Market for Sacral Nerve Stimulation Devices 2010-2017

    • Figure 4-3: The World Market for Sacral Nerve Stimulation Devices 2010-2017

    • Table 4-5: The World Market for Vagus Nerve Stimulation Devices 2010-2017

    • Figure 4-4: The World Market for Vagus Nerve Stimulation Devices 2010-2017

    • Table 4-6: The World Market for Deep Brain Stimulation Devices 2010-2017

    • Figure 4-5: The World Market for Deep Brain Stimulation Devices 2010-2017

    • Table 4-7: The World Market for Gastric Electrical Stimulation Devices 2010-2017

    • Figure 4-6: The World Market for Gastric Electrical Stimulation Devices 2010-2017

    • Table 4-8: Implantable Electrical and Neurological Stimulation Market by Product Segment 2010-2017

    • Figure 4-7: Implantable Electrical and Neurological Stimulation Market by Product Segment 2010-2017

    • Figure 4-8: Implantable Electrical and Neurological Stimulation Market by Product Segment 2012 and 2017

CHAPTER SIX: MARKET SUMMARY
    • Table 6-1: Electrical and Neurostimulation Equipment/Device Market by Application Method, 2010-2017

    • Figure 6-1: Electrical and Neurostimulation Equipment/Device Market by Application Method, 2010-2017

    • Figure 6-2: Electrical and Neurostimulation Equipment/Device Market by Application Method, 2012 and 2017

    • Table 6-2: Electrical and Neurostimulation Equipment/Device Market Estimated Sales by Geographic Region 2010-2017

    • Figure 6-4: Electrical and Neurostimulation Equipment/Device Market Estimated Sales by Geographic Region 2010-2017

    • Figure 6-5: Electrical and Neurostimulation Equipment/Device Market Estimated Sales by Geographic Region 2012 and 2017

To order this report: Cardiovascular Devices Industry: Markets for Electrostimulation Devices (Neurostimulation, Cardiac Rhythm Management, Fracture Healing and Others)
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Contact:
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http://www.sacbee.com/2012/08/06/4696746/markets-for-electrostimulation.html

Thursday, August 2, 2012

Willingness to Accept and Pay for Implantable Tinnitus Treatments: A Survey.

2012 Jul 31. doi: 10.1111/j.1525-1403.2012.00487.x. [Epub ahead of print]

Willingness to Accept and Pay for Implantable Tinnitus Treatments: A Survey.

Source

MicroTransponder, Inc., 2802 Flintrock Trace, Suite 225, Austin, TX, USA; Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, IA, USA.

Abstract

Objectives:  At present, there is no cure for tinnitus. Neurostimulation techniques have shown great promise, but it is uncertain whether they will gain acceptance because of their invasive nature. We have previously demonstrated that pairing acoustic stimuli with vagus nerve stimulation (VNS) also has potential as a viable tinnitus treatment approach. Methods:  We conducted a survey on tinnitus sufferers that emphasized questions related to a willingness to pay for the treatment of tinnitus, including VNS. Four hundred thirty-nine individuals responded to an Internet survey modeled after a recent study by Tyler. Results:  The average age was about 47 years. Ninety-four percent reported that they had health insurance. Almost 40% had spent between $500 and $10,000 on tinnitus therapies. Almost three-fourths said that they would be willing to have a device implanted if it reduced tinnitus annoyance by half. About 70% of those with very loud tinnitus would be willing to have a temporary implant, and about 60% would be willing to have a permanent implant even if the device suppressed their tinnitus by only half of its annoyance. Only 10% of patients with SOFT tinnitus would be willing to have a permanent implant if the therapy suppressed their tinnitus by only half of its annoyance. Conclusions:  We conclude that implanted devices, such as a VNS, will be an acceptable form of tinnitus treatment for many who suffer from tinnitus. The results of this survey indicate that VNS tone pairing would be an acceptable therapeutic solution for individuals with moderate to severe tinnitus and should be developed for the market.
© 2012 International Neuromodulation Society.
PMID:
22849609
[PubMed - as supplied by publisher]

http://www.ncbi.nlm.nih.gov/pubmed/22849609

Wednesday, December 15, 2010

Neurostimulation Poised to Take On Tough Seizures

Neurostimulation Poised to Take On Tough Seizures

12/15/10 
SAN ANTONIO – It’s still too soon to know whether
neurostimulation will be the therapeutic advance that treatment-refractory
epilepsy patients have been waiting for, but the possibility that it might be
has the epilepsy community buzzing.
For approximately 30% of epilepsy patients, seizures cannot
be controlled with antiepileptic drugs or surgery. New long-term safety and
efficacy data for vagus nerve simulation (VNS) and the results of recent
pivotal trials of two approaches to direct brain stimulation offer beacons of
hope to these patients, Dr. Gregory K. Bergey said in a plenary session on
neurostimulation at the annual meeting of the American Epilepsy Society.
"One of the frustrating things for those of us treating
patients with epilepsy has been the fact that, although a number of new
antiepileptic drugs have been developed over the past 10-15 years and most are
better tolerated and have better pharmacokinetic profiles than earlier drugs,
the number of patients with seizures that don’t respond to medical therapy has
not been significantly reduced," said Dr. Bergey, director of the Johns
Hopkins Epilepsy Center, Baltimore.
"So we’re stepping back and saying, ‘Is there some other
way we can treat these patients?’ That has been the impetus for looking at
neurostimulation, which has been around for well over a decade, and what we’re
seeing is exciting."
Although the 40%-50% response rates observed in direct brain
stimulation trials do not appear to be overwhelming, "this is just the
beginning," Dr. Bergey stressed in an interview. "As opposed to a
drug trial, where you go up to a certain dose and it either works or it doesn’t
work, in the case of neurostimulation we don’t know the optimal stimulus parameters,
and I think that’s what you’re going to begin to see over the next several
years," he said.
"There’s going to be a lot of investigation into
neurostimulation of the brain structures to try to figure out who are the best
candidates and what the best stimulus parameters are. It’s easy to say we’re
stimulating the brain, but do we stimulate 100 times per second, 50 times per
second, 25 times per second, and what should the stimulus intensities be?"
Vagus Nerve Stimulation. Currently, Cyberonics’ VNS
Therapy System is the only Food and Drug Administration–approved form of
neurostimulation for the treatment of epilepsy. The technology was approved in
1997 for the treatment of medically refractory partial-onset seizures in
patients 12 years or older. It consists of a stimulator that sends electric
impulses to the left vagus nerve in the neck via a lead wire that is implanted
under the skin. Studies since 1997 have indicated efficacy in generalized
seizure disorders and children as well, according to Dr. Elinor Ben-Menachem,
professor of neurology and epilepsy at the Institute for Clinical Neurosciences
and Physiology, Göteborg (Sweden) University.
To date, more than 60,000 patients worldwide have been
treated with VNS, and studies suggest that approximately 50% of patients who
undergo the procedure experience a long-term decrease in mean seizure frequency
of 50% or more. But fewer than 10% become seizure-free, Dr. Ben-Menachem said
during the neurostimulation plenary presentation.
"[VNS] has a long history now, and what we know is that
it does not cure or affect seizures immediately. We actually don’t notice a
change in seizure activity until about 18 months or 2 years after
starting."
For example, a recent long-term follow-up study of VNS
patients in the Czech Republic showed that at 1 year post implantation, 44.4%
of patients achieved more than 50% seizure reduction. The percentage of
patients who reached that level of seizure reduction then increased from 58.7%
at 2 years after implant to 64.4% at 5 years. At the 5-year mark, 15.5% of the
patients had achieved a minimum 90% seizure reduction, and 5.5% were seizure
free (Seizure
2009;18: 269-74
).
The mechanism of action of VNS remains uncertain, but a
number of possibilities have been suggested, including arousal of the reticular
formation; stimulation of locus coeruleus and noradrenaline pathways; changes
in a neurotransmitter, amino acid, or neuropeptide; or indirect thalamus stimulation,
according to Dr. Ben-Menachem. "It’s also possible that there is long-term
learning through synaptic structural changes," she said. "The more I
work with this, the more I think it is a learning paradigm. It’s like learning
to play the piano. You can’t just sit down and play, you have to redo and redo
until the brain is trained."
In a recent study of 144 patients who had undergone VNS
implantation, 10 patients were seizure free for more than 1 year post
implantation, 89 patients experienced seizure improvement, and no changes were
observed in 45 patients. "Stepwise multivariate analysis showed that
unilateral interictal epileptiform discharges [IEDs], cortical dysgenesis, and
younger age at implantation were independent predictors of seizure freedom in
the long-term follow-up," they wrote (Seizure
2010;19: 264-8
).
Most of the adverse events associated with VNS therapy, such
as hoarseness and cough, tend to be mild and are stimulation related, Dr.
Ben-Menachem explained. "Typically, they occur only during stimulation and
they generally diminish over time on their own, or they may be diminished or
eliminated by adjustment of the parameter settings."
Programmed Deep Brain Stimulation. The programmed deep
brain stimulation device manufactured by Medtronic, one of the two emerging
neurostimulation treatments for intractable epilepsy that is under FDA review,
demonstrated efficacy in a pivotal trial that involved stimulation in the anterior
thalamus. This site has connections with the temporal lobe, which is a common
site for the origin of partial seizures, Dr. Bergey explained.
The device, which is already approved for Parkinson’s
disease, comprises four deep brain electrodes that are implanted bilaterally
into the target structure with a pulse generator placed below the clavicle. It
delivers stimuli at scheduled intervals "to hopefully modulate and reduce
the number of seizures the patient is having," he said.
In the Medtronic-funded Stimulation of the Anterior Nucleus
of the Thalamus for Epilepsy (SANTE) study, 110 patients with medically
refractory partial seizures were implanted with the device and randomized to
intermittent bilateral stimulation (1 minute on/5 minutes off) or no-stimulation
for a 3-month blinded stage, followed by unblinded stimulation for all of the
patients (Epilepsia
2010;51:899-908
). At the end of the blinded period, patients who received
stimulation experienced a median seizure reduction of 40.4%, compared with
14.5% of patients with the stimulator off, reported study coauthor Dr. Vincenta
Salanova of Indiana University, Indianapolis.
In the open-label follow-up, 56% of all the patients had
greater than 50% seizure reduction at 2 years, and there was a median 68%
reduction in seizures among the 42 patients for whom 3-year data were
available. Over the course of the study, "14 [12.7%] of the patients were
seizure free for at least 6 months," she reported in a press briefing at
the meeting.
Although the mechanism of action is not fully understood, Dr.
Salanova said that "the thalamus has connections between the limbic system
and the frontal lobe, so it’s possible that high-frequency stimulation may
prevent the propagation of seizures."
Five deaths occurred in the study population, but none were
attributed to lead implantation or stimulation, Dr. Salanova stressed. There
were no symptomatic or clinically significant hemorrhages associated with implantation,
but 4.5% of patients experienced asymptomatic intracranial hemorrhages –
detected via neuroimaging – that were not clinically significant. Additionally,
two patients experienced seizures that were linked to the stimulus, which were
resolved by lowering the voltage.
Direct stimulation of the hippocampus may also offer seizure
relief in some patients, according to Dr. Richard Wennberg of the University of
Toronto. "The hippocampus is clinically recognized as a region of high
epileptogenicity, and animal studies have demonstrated antiepileptic properties
of electrical fields applied to the region," he said in a presentation
during the neurostimulation plenary session, noting that the goal of direct
hippocampal stimulation is to prevent seizure generation and spread from the
temporal limbic region.
To date, the experimental procedure has been evaluated in
small series and has shown some efficacy, Dr. Wennberg said. For example, in a
recent study designed to assess the effect of continuous electrical stimulation
of the hippocampus bilaterally, two patients with seizures from both mesial
temporal lobes who were not candidates for surgical resection were implanted
bilaterally with two four-contact electrodes along the hippocampal axis. After
randomization to either stimulation on or off conditions for 3-month intervals,
seizure frequency decreased by 33% during stimulation, and stayed and remained
lower by 25% for the 3 months after stimulation was turned off, after which the
seizure frequency returned to baseline, the authors reported. Although seizure
frequency was reduced both during and for a period after bilateral hippocampal
stimulation, "the overall impact in this study is not as robust as has
been previously reported," the authors stated (Epilepsia
2010;51:304-7
).
Responsive Neurostimulation. Another direct brain
neurostimulating technology under FDA review is the Responsive Neurostimulator System
(RNS) by NeuroPace. "The system detects and aborts [functional mapping]
induced afterdischarges in the brain to prevent seizures," explained Dr.
Lawrence J. Hirsch of Columbia University in New York. "It is designed to
respond within seconds to abnormal activity in the brain by delivering a series
of up to five stimuli to terminate the abnormal discharge."
The RNS device is implanted in a recess of the skull, and is
connected to up to two four-contact electrodes that are placed within the brain
or on the brain surface, depending on where the seizures begin. The device
collects and stores seizure information, which the patient subsequently
downloads to a laptop using a wand. Physicians can access the stored
electrocorticograms via a secure Web page through which they can adjust
detection and stimulation parameters specific to the individual patient, Dr.
Hirsch said during the neurostimulation plenary session.
In the pivotal clinical trial of the RNS system, 191 patients
with medically intractable, partial-onset seizures localized to one or two foci
received the cranial implant. During a blinded period, patients received active
or sham stimulation, followed by an open-label phase in which all the patients
received active stimulation. During the entire blinded evaluation period,
active stimulation was associated with a mean 37.9% reduction in seizure
frequency, compared with a mean 17% reduction during the sham activation, Dr.
Hirsch said.
"In the final month of the blinded period – month 4 to 5
– the respective reduction in seizure frequency was 42% and 9%." During
the last 3 months of the open-label period, "47% of the patients had a
greater than 50% seizure reduction," he said. "And at 4 years post
implant, more than 50% of the patients had at least a 50% reduction in seizure
frequency."
A subset analysis showed that neither prior surgery nor the
number of seizure foci had an effect on treatment response, Dr. Hirsch noted.
"It also showed that [RNS] is possibly more effective with medial temporal
onset."
With respect to adverse events, implant site infections were
reported in 5% of the patients, and led to explantation in 2%. The combined
rate of status epilepticus reported in all trials of the device (256 patients)
was 3.5%, and included episodes occurring between 5 months and 5 years post
implant. Intracranial hemorrhage was reported in 4% of the patients, and
included only one patient with neurological sequelae, which was chronic
headache, he said.
The chronic, intracranial EEG recordings provided by the RNS
technology have other potentially valuable uses, including seizure
prediction/warning; seizure awareness and counting as a way to assess treatment
efficacy; identification of circadian, catamenial, and other ictal and
interictal patterns; and the lateralization of bitemporal seizures, Dr. Hirsch
said.
Dr. Bergey disclosed financial relationships with Pfizer,
UCB, and Eli Lilly. Dr. Ben-Menachem disclosed financial relationships with
UCB, Eisai, Janssen, Cilag, Cyberonics, Lundbeck, and Sunovion. Dr. Wennberg
disclosed a financial relationship with Medtronic. Dr. Hirsch reported having
no financial disclosures.
Medtronic's DBS system (top left) stimulates the anterior
nucleus of the thalamus, whereas NeuroPace's RNS device (bottom left) responds
to abnormal activity in targeted areas and Cyberonics' VNS Therapy System
(right) periodically stimulates the left vagus nerve. (Photo Credit: top left:
(c) Medtronic Inc., bottom left: (c) NeuroPace Inc., right: (c) Cyberonics
Inc.)

* CORRECTION, 12/16/2010: The original version of this
article misstated the action of the Responsive Neurostimulator System (RNS) by
NeuroPace. The system detects and aborts abnormal discharges in the brain. Also,
the programmed deep brain stimulation device manufactured by Medtronic contains
one deep brain electrode on each side, not four. This version has been
updated.

http://www.internalmedicinenews.com/news/neurology/single-article/neurostimulation-poised-to-take-on-tough-seizures/17d1537114.html