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5 Articles in this Series
Introduction
2018 IASP World Congress on Pain: A Preview
Informal Social Support for Pain: Moving the Research Forward
Spinal Cord Stimulation Evidence: What's Available and What's Needed
Symptomatic Treatment of Painful Diabetic Neuropathy
Translating Trials into Practice from a Primary Care Perspective

Spinal Cord Stimulation Evidence: What's Available and What's Needed

John Markman, MD, recounts what’s currently on the table for SCS and how much more is needed for adequate pain relief. A 2018 IASP World Congress on Pain highlight.

In a presentation titled “Yes, We Now Have the Evidence, But..,.” John Markman, MD, professor of neurosurgery at the University of Rochester, outlined some shortcomings of the existing evidence for spinal cord stimulation (SCS) including heterogeneous populations studies.Dr. Markman’s main concern with SCS is the level of uncertainty he has with the procedure—how it works, whom it works for, and the non-specific treatment effects of the procedure. To rectify this, he has begun to conduct crossover studies in his practice to get a better grasp of these questions. “Imagine if, in 2018, the indication for putting in a spinal cord stimulation system were as matched to mechanism as a cardiac pacemaker,” Dr. Markman posed the audience, noting that SCS implementation remains heavily dependent on self-reporting.

Several video interviews with patients of Dr. Markman were played during the talk, the first being a patient who underwent a trial of neuromodulation for chronic lower back and leg pain after spine surgery. The patient recounted, that, between the two systems applied, only one reduced pain by about 10%. When asked if the patient would like to continue the systems longer to get a better idea of leading to pain reduction and adjustments, the patient declined, saying that he sought immediate relief and wanted to go forward with implantation. Dr. Markman said he uses various systems with his patients to determine what specific process they are most comfortable with and what provides the most effective pain reduction, “just as you wouldn’t go into a shoe store and try on just one pair.”

Existing Evidence 

SCS technology is still evolving, Dr. Markman said. While self-reporting is still prevalent, what has changed in the past five decades is the upgrade from a single case report to prospective, multinational, randomized clinical trials. One landmark trial, for instance, randomized 100 failed back surgery syndrome (FBSS) patients with predominant leg pain of neuropathic radicular origin to receive SCS plus conventional medical management (the SCS group) or conventional medical management alone (the CMM group) for at least 6 months.Compared with the CMM group, the SCS group experienced improved leg and back pain relief, quality of life, and functional capacity, as well as greater treatment satisfaction. Between 6 and 12 months, five SCS patients switched to CMM, and 32 CMM patients switched to SCS. At 12 months, 27 SCS patients (32%) had experienced device-related complications. In selected patients with FBSS, SCS provided better pain relief and improved health-related quality of life and functional capacity compared with CMM alone.

Other significant trials for SCS include North, et al, from 2005,3 and Kemler, et al, from 2008.4 “This is an era marked by open-label studies,” Dr. Markman said. Enormous technical innovation, improvement of clinical trial designs, and larger study populations (prospective, head-to-head), are just some of the factors leading these recent advancements.

Evidence Still Needed

Despite the success in recent years of more trials being applied to SCS, many questions have yet to be addressed. For instance, the totality of study participants to date is only 973, a study population that is “poorly characterized,” according to Dr. Markman. “Chronic pain after spine surgery, that’s an iatrogenic injury, and it's a very heterogeneous group of patients, some of who have axial-predominant neuropathic pain.” In one study,5 of 97 subjects who completed a trial of HF10 therapy, 90 (92.8%) had significant back pain relief and were eligible for an implant of an SCS system. In comparison, 81 of 92 subjects (88.0%) were successfully trialed with traditional SCS (P = 0.33). “Which is incredibly high in my opinion. Think about in your own practice how many times you’ve tried someone on a therapy for a heterogeneous pain problem, some of which is nociceptive, some of which is neuropathic…and 92% of them get relief? It just doesn’t reflect anything in my practice,” Dr. Markman said.

In addition to this, the lack of blinding in trials, as well as the lack of controls, makes the results weaker by design. External challenges include the regulatory framework for devices being much less rigorous for analgesic drugs, for example. Study sponsorship has also been an issue, as many current studies that are industry-sponsored have a clear publication bias compared to payor studies that are normally negative in nature, Dr. Markman suggested.

Devices are also constantly changing. “It’s a moving target," he said. "It’s like comparing your phone in 1967 to your phone today. It’s not really a great comparison." A generation of studies now has emerged that has made comparisons to figure out what the on-target analgesic actions are and what non-specific treatment effects have been seen. “The disruption in technology is changing the stakeholders and how they engage,” Dr. Markman said. He concluded by noting that, due to an impact-style meeting having an enormous accelerant effect on deciding the "rules of the road" for oral analgesic trials, a group is now meeting with representatives from the International Neuromodulation Society and the North American Neuromodulation Society to develop consensus guidelines for spinal cord stimulation.

More on this topic with Paul J. Christo, MD.

Sources

1. Markman J. " Yes We Now Have the Evidence, But…", presented at 2018 IASP World Congress on Pain, September 12-16, in Boston, MA.

2. Kumar K, Taylor RS, Jacques L, et al. Spinal cord stimulation versus conventional medical management for neuropathic pain: a multicentre randomised controlled trial in patients with failed back surgery syndrome. Pain. 2007;132(1-2):179-188.

3. North RB, Kidd DH, Farrokhi F, et al. Spinal cord stimulation versus repeated lumbosacral spine surgery for chronic pain: a randomized, controlled trial. Neurosurg. 2005;56(1):98-107.

4. Kemler MA, De Vet HC, Barendse GA, et al. Effect of spinal cord stimulation for chronic complex regional pain syndrome Type I: five-year final follow-up of patients in a randomized controlled trial. J Neurosurg. 2008;108(2):292-298.

5. Kapural L, Yu C, Doust MW, et al. Novel 10-kHz High-frequency Therapy (HF10 Therapy) Is Superior to Traditional Low-frequency Spinal Cord Stimulation for the Treatment of Chronic Back and Leg Pain. The SENZA-RCT Randomized Controlled Trial. Anesthesiol. 2015;123(4):851-860.

Next summary: Symptomatic Treatment of Painful Diabetic Neuropathy
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