Clinical Question

Is spinal cord stimulation a safe and effective treatment for low back pain?

Evidence-Based Answer

When studied for up to six months, spinal cord stimulation likely does not improve pain, function, or health-related quality of life vs. placebo. When studied for up to 12 months, spinal cord stimulation and optimal medical management may slightly improve back function and reduce opioid use. It is also uncertain if spinal cord stimulation can improve outcomes in the immediate term (i.e., less than one month). The long-term adverse effects and complications of spinal cord stimulation have not been quantified and are not fully understood.¹ (Strength of Recommendation: B, inconsistent or limited-quality patient-oriented evidence.)

Practice Pointers

Chronic low back pain is the leading cause of years lived with a disability and the most common musculoskeletal problem worldwide.² Spinal cord stimulation involves surgically implanting a device in the lower back or trunk that generates electrical impulses and delivers them to the spinal cord via electrodes within the posterior epidural space.¹ The mechanism of action is not well understood but is thought to work using the gate-control theory of pain, in which activation of non-nociceptive nerve signals attenuate pain signals sent to and processed by the brain. Inhibition of sympathetic nervous system activation is also a proposed action. Preimplantation trials are typically performed with percutaneous leads to screen for a response. If a patient achieves at least 50% pain relief, spinal cord stimulation implantation may be considered. The average cost of spinal cord stimulation implantation is $30,000.¹

The authors of this review studied spinal cord stimulation as a potential treatment intervention for low back pain. The review included 13 randomized studies (three multinationals and others in Belgium, Germany, Israel, Poland, the United Kingdom, Norway, and the United States) with 699 participants. Sample sizes ranged from four to 218 participants per trial to assess spinal cord stimulation benefits and harms. Study participants were adults (18 years or older) with chronic low back pain (greater than 12 weeks’ pain duration), with or without leg pain, including people classified as having failed back surgery syndrome. The diversity of participants was not well-described, but the mean age of study participants ranged from 47 to 59 years. Participants with chronic low back pain caused by serious spinal pathology (e.g., fracture, cancer, infection) were excluded. Leg pain was not defined and was not classified as radiculitis vs. radiculopathy. Not all trial reports described a preimplantation trial; seven studies included patients who already had a spinal cord stimulation implant. Scales used to determine effect included a 100-point visual analog pain scale, the 100-point Roland-Morris Disability Questionnaire, and the Oswestry Disability Index.

The primary evaluation was spinal cord stimulation vs. placebo—including a stimulator that was off, turned on for initial programming only, or switched on but not emitting a signal. Primary outcomes included pain intensity, physical function, quality of life, and self-assessed effectiveness from the patient’s perspective. No studies included a follow-up date of more than six months. Of the 13 studies, only one study with a sample size of 50 patients (mean age = 50 years) measured outcomes at six months, with most reporting only immediate-term (less than one month) outcomes. In that study of 50 patients, at six-month follow-up, there was no statistical benefit for spinal cord stimulation on back pain, function, or health-related quality of life.

Three separate parallel-group trials of spinal cord stimulation plus medical management vs. nonstandardized optimal medical management alone (e.g., physical therapy, acupuncture, pharmacologic interventions) suggest that adding spinal cord stimulation to medical management may slightly improve function and slightly reduce opioid use in the medium-term (i.e., one to less than 12 months). These trials did not report long-term outcomes and were assessed to have overall low-certainty evidence by GRADE. Mean medium-term physical function (on a 0- to 100-point scale, in which lower scores represent better function) was 7.7 points lower with the addition of spinal cord stimulation to medical management alone (95% CI, 3.6 to 11.8 points lower; 290 participants) and opioid medicine use was 15% lower (95% CI, 0% to 27% lower; 290 participants). There was no standard definition of medical management. Adverse events were not always reported but included infection, lead migration, damage to the spine or nerves, and revision surgery.

Significant bias existed in all 13 studies. Five studies were found to have selection bias, 10 had performance and detection bias, and several others had attrition bias, selective reporting bias, and other potential biases. Most studies were small, with imprecise estimates of effect and inconsistency for what outcomes and adverse effects were reported. Data were insufficient to calculate the number needed to treat or the number needed to harm.

Professional societies in the United States do not have specific recommendations for spinal cord stimulation. Internationally, the National Institute for Health and Care Excellence published a 2008 guideline recommending spinal cord stimulation as an option for patients experiencing significant neuropathic pain for more than six months and who underwent a stimulation trial.³ However, because of the level of uncertainty available in this Cochrane review, the data do not support the use of spinal cord stimulation to manage low back pain outside of a clinical trial, and it is unclear if spinal cord stimulation has long-term clinical benefits to reasonably outweigh the costs and risks of surgical intervention.

The practice recommendations in this activity are available at https://www.cochrane.org/CD014789.

The opinions and assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Uniformed Services University of the Health Sciences, U.S. Department of Defense, or U.S. government.