Among patients with chronic radicular pain after lumbar spine surgery, spinal cord burst stimulation, compared with placebo stimulation, results in no significant difference in back pain-related disability, new research has shown.
The study, the findings of which were published in JAMA by Sozaburo Hara (St Olavs University Hospital, Trondheim, Norway) et al, sought to investigate the efficacy of spinal cord burst stimulation—which involves the placement of an implantable pulse generator connected to electrodes with leads that travel into the epidural space posterior to the spinal cord dorsal columns—in patients with chronic radiculopathy after surgery for degenerative lumbar spine disorders.
According to Hara et al “the use of spinal cord stimulation for chronic pain after lumbar spine surgery is increasing, yet rigorous evidence of its efficacy is lacking”.
The placebo-controlled, crossover, randomised clinical trial included 50 patients and was conducted at St Olavs University Hospital, with study enrolment from 5 September 2018 to 28 April 2021. The date of final follow-up was 20 May 2022.
Patients underwent two three-month periods with spinal cord burst stimulation and two three-month periods with placebo stimulation in a randomised order. Burst stimulation consisted of closely spaced, high-frequency electrical stimuli delivered to the spinal cord. The stimulus consisted of a 40-Hz burst mode of constant-current stimuli with four spikes per burst and an amplitude corresponding to 50%–70% of the paraesthesia perception threshold.
The primary outcome was difference in change from baseline in the self-reported Oswestry Disability Index (ODI; range: 0 points [no disability] to 100 points [maximum disability]; the minimal clinically important difference was 10 points) score between periods with burst stimulation and placebo stimulation. The secondary outcomes were leg and back pain, quality of life, physical activity levels, and adverse events.
Of the 50 patients who were randomised (mean age, 52.2 [standard deviation (SD), 9.9] years; 27 [54%] were women), 47 (94%) had at least one follow-up ODI score and 42 (84%) completed all stimulation randomisation periods and ODI measurements.
The mean ODI score at baseline was 44.7 points and the mean changes in ODI score were –10.6 points for the burst stimulation periods and −9.3 points for the placebo stimulation periods, resulting in a mean between-group difference of −1.3 points (95% confidence interval [CI], −3.9 to 1.3 points; p=0.32).
None of the pre-specified secondary outcomes showed a significant difference and nine patients (18%) experienced adverse events, including four (8%) who required surgical revision of the implanted system.
Speaking to Spinal News International, Sasha Gulati, who supervised the trial, said: “Considering the limited high-quality evidence for benefits and the increasing costs associated with its use, spinal cord stimulation for chronic radicular pain outside well-designed clinical trials is of questionable benefit and must be weighed against the common incidence of device-related complications.”