Spinal cord stimulation at 10 kHz is associated with reduced lumbosacral pain, decreased disability, and a reduction in opioid consumption in patients with refractory back pain who are surgically naive, according to research published in Anaesthesia.
The use of 10 kHz spinal cord stimulation (Senza® system, Nevro Corp.) is a “novel, subperception, stimulation paradigm” providing pain relief without paresthesia. Study participants had not undergone lumbosacral surgery in the 2 studies — SENZA-EU and SENZA-RCT — and were included in a subgroup analysis to evaluate the efficacy of spinal cord stimulation.
SENZA-EU was a prospective, multicenter, open-label study conducted at 2 European centers between August 2009 and February 2011. Participants had chronic back pain, with or without leg pain, that was refractory to conventional treatment for at least 6 months. Average pain scores were measured ≥5.0 cm using the Visual Analogue Scale (VAS; 0-10 cm scale where 0 = no pain and 10 = worst pain imaginable) in the past 7 days.
SENZA-RCT was a multicenter, randomized controlled trial conducted in 10 centers in the US between June and December 2012. Participants in this study had chronic, intractable back pain and/or leg pain refractory to conservative therapy for at least 3 months. Average back and/or leg pain VAS measured ≥ 5.0 cm over 7 days, and the Oswestry Disability Index (ODI) score was 41% to 80% out of 100%.
Study data were separately analyzed for each group, and as a combined cohort for mean pain VAS score, percentage of pain relief from baseline at 3, 6, and 12 months after spinal cord stimulator implantation, 12-month responder rates, and 12-month remission rates.
A total of 27 participants had 12-month data available and were included in the current study (SENZA-EU, n=15; SENZA-RCT, n=12). One study subject was lost to follow-up, leaving 26 participants for analysis. The 2 subgroups were similar in terms of age, number of years since diagnosis, back and leg pain scores, and disability scores. More women were included in the SENZA-EU subgroup.
Daily opioid dose was higher in the SENZA-RCT subgroup (≥50 morphine milligram equivalents [MME]). Pain causation in most SENZA-EU participants was degenerative spine disease, facet degeneration, spinal stenosis, scoliosis, and/or radiculopathy. The cause of pain in most SENZA-RCT study participants was radiculopathy, spondylosis, and/or degenerative disc disease.
At month 3, both subgroups of participants reported a decrease in back or leg pain from baseline. In the SENZA-RCT group, 75% (9/12) of participants responded for both back and leg pain, while 71% (10/14) and 70% (7/10) of participants in the SENZA-EU group were responders for back and leg pain, respectively. The combined responder rate for the cohort was 73% (19/26) for back and leg pain, with 42% (11/26) of participants reporting a reduction in back pain upwards of 80% from baseline.
In the SENZA-RCT group, 67% (8/12) and 75% (9/12) of participants met criteria for remission of back and leg pain, respectively, at 12 months; rates were 57% (8/14) and 60% (6/10) in the SENZA-EU subgroup.
Across the total cohort, 26 participants had complete ODI scores available at baseline and 12 months. Based on these scores, 5/26 participants were categorized as disabled, 20/26 as severely disabled, and 1 as moderately disabled. By 12 months, 1/26, 10/26, and 13/26 participants met these categories, and 2/26 participants were categorized as minimal.
Twenty-one participants had opioid use data at baseline and 12 months. At baseline, 2/21 used 0 MME, 10/21 used 1-49 MME, 3/21 used 50-90 MME, and 6/21 used more than 90 MME. At 12 months, these numbers were 8/21, 7/21, 3/21, and 3/21, respectively. Average opioid consumption “more than halved” from mean (standard deviation [SD]) baseline values of 85.3±21.9 MME to 39.8±12.9 MME at month 12.
Nearly one-third of participants (29%, 6/21) stopped taking opioids; 24% (5/21) decreased opioid intake, 33% (7/21) had no change in opioid intake, and 14% (3/21) increased intake, with a mean SD increase of 26.7±7.3 MME.
Two-thirds of the participants (6/9) taking ≥50 MME at baseline, mean SD opioid consumption more than halved (173.2±32.6 MME to 72.6±26.0 MME). At 12 months, these participants reduced or eliminated their opioid intake.
Study limitations include small sample size, lack of a placebo-control group, and some differences between the SENZA-EU and SENZA-RCT subgroups including heterogeneity in participants.
The study authors noted the findings are clinically valuable as they await results from an ongoing, randomized, controlled trial comparing spinal cord stimulation with conventional medical management (ClinicalTrials.gov identifier NCT03680846).
“Our analysis showed 10 kHz spinal cord stimulation reduced pain, disability, and opioid consumption in patients living with nonsurgical refractory back pain,” the researchers concluded. Given the high prevalence of back pain, related disability in men and women, and the escalating economic burden it creates, improvements in the care of this patient population are an essential consideration for clinicians and health care providers.
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Al-Kaisy A, Van Buyten JO, Kapural L, Amirdelfan K, Gliner B, Caraway D, et al. 10 kHz spinal cord stimulation for the treatment of non-surgical refractory back pain: subanalysis of pooled data from two prospective studies. Anaesthesia. 2020;75(6):775-784. doi:10.1111/anae.15036