January 2019 issue
January 31, 2019 | Nearly 3000 pain doctors, neurosurgeons, neural engineers and related professionals attended the 2019 meeting of the North American Neuromodulation Society in Las Vegas, NV earlier this month. Several neuromodulation device vendors used the show to report study results or new product introductions. Keynote speaker Sam Quinones, a journalist and author, related stories of how the pharmaceutical industry used an army of sales reps to push opioids on doctors and patients in the last two decades.
The opening plenary session examined several paradigm shifts in neuromodulation, including closed-loop stimulation and the use of trialing. Sam Eldabe from James Cook University Hospital in Australia summarized clinical results that cast some doubt on the long-term benefits of performing trials with temporary leads before implanting an SCS device in a patient. The dangers of both false positive and false negative determination—or a situation where the vast majority of trial participants are receiving benefit—seem to negate the economic or therapeutic advantage of trialing.
Negy Mekhail from the Cleveland Clinic discussed the value of closed-loop neurostimulation, which served as a lead-in for a later session showing positive results from a trial of Saluda Medical’s Evoke system compared to open-loop SCS devices.
Abbott announced positive results from a new multicenter study of the company’s BurstDR stimulation which showed that lower-energy, intermittent doses of BurstDR stimulation—known as “microdosing”—can provide pain relief that is just as effective as standard doses of BurstDR stimulation in people with chronic intractable pain. The company’s BOLD study shows a potential way to prolong SCS battery life while offering optimal pain relief. The research may also provide a path toward ensuring lower-maintenance recharge-free SCS devices offer similar battery longevity as rechargeable SCS systems, which carry a higher burden for patients.
In a separate study called BURST(able), data showed that patients who no longer received effective pain relief from their SCS therapy experienced restored pain control and reduced opioid dependency when they switched to an Abbott device offering the BurstDR waveform. Loss of pain relief is the most common cause for patients seeking an explant of their SCS system, and combatting this loss of efficacy addresses one of the key problems seen in long-term SCS therapy.
Stimwave presented results from the SURF RCT study, a prospective, randomized, multi-center clinical trial of the company’s wireless SCS system comparing a variety of waveform options without a separate trialing device. Study participants were able to optimize their pain relief outcomes and dial in the appropriate waveform and frequency customized to their unique pain relief needs. Notable, in the two-arm study, high and low frequency, back and leg pain responders were over 92 percent and 86 percent respectively.
Investigators affiliated with Mainstay Medical presented results from company’s ReActiv8-B clinical trial, which failed to meet its primary efficacy endpoint, owing in large-part to a 47 percent response rate in the sham stimulation arm of the trial at 90 days. Principal investigator Chris Gilligan from Brigham & Women’s Hospital pointed out that the difference between sham and treatment arms would likely have been statistically significant at almost any other time epoch than 90 days. He also said that the FDA disallowed consideration of seven responders from the treatment group who had increased their use of meds during the trial, even though it was for conditions unrelated to their back pain. “Maybe we didn’t set the trial up right,” he conceded. Still, Mainstay CEO Jason Hannon believes there is a path to FDA approval based on the longer-term data and on the statistically significant results from subpopulations within the trial group.
In a lunch session sponsored by Medtronic, Ali Rezai from West Virginia University discussed his institution’s efforts to develop biomarkers for chronic pain and to identify physiological, cognitive, and psychological parameters that would contribute to improved neuromodulation response. Rezai’s team is developing digital health tools based on tablet and smartphone use that would complement future neuromodulation therapies.
In a session devoted to functional recovery, Susan Harkema from the University of Louisville gave an update on her team’s use of epidural stimulation to restore function in individuals with spinal cord injury. The Louisville team has performed 16 procedures to date and is now implanting about one new patient per month. She stressed that specific intent from the user is required in order to effect locomotion in paralyzed individuals who have gone through the therapeutic regime and that motor response is absent without the stimulation. She also highlighted autonomic benefits of epidural stimulation, including blood pressure stabilization.
Patricio Riva Posse from Emory University gave an update on progress with DBS for psychiatric disorders. He highlighted novel clinical trial designs such as a recent Dutch study that examined response in responders after the stimulation was turned off for a period and then again when the therapy was resumed. The responders became non-responders during the non-stimulation trial period and then became responders again once the DBS restarted. Riva Posse pointed out that connectomics-based targeting using procedures developed by Cameron McIntyre from Case Western Reserve University improved response to 77 percent compared to 41 percent when traditional coordinate-based targeting was used.
Marom Bikson from City College of New York described a strategy for improving response in tDCS neuromodulation systems. He said it was important to make functional neurons active so that they would respond better to the electrical stimulation once applied. Bikson pointed out that specific synapses can be boosted with the appropriate application of stimulation.
