Background
Low back pain is a leading cause of disability around the world. Spinal cord stimulation, a surgical treatment involving implantation of a device that applies electric impulses to the spinal cord, has been suggested to improve pain in people with long-term low back pain. This study aimed to review evidence regarding the benefits and harms of this procedure for people with low back pain.
Study characteristics
We searched online databases and registries for relevant studies on 10 June 2022. We found 13 trials with 699 participants. Of these, 55% were female and the average age of study participants ranged from 47 years to 59 years. The average duration of low back pain amongst study participants varied from 5 to 12 years. Ten of the 13 studies had financial ties to manufacturers of spinal cord stimulation systems.
Key findings
No studies have tested whether spinal cord stimulation surgery is better than placebo (sham or 'dummy' treatment) in people followed up for longer than 6 months. This means that the benefits of the treatment in the long term are unknown. Most of the available studies only measured outcomes at less than 1 month after treatment, and only 1 study measured outcomes at 6 months after treatment:
Pain intensity (0 to 100, lower scores mean less pain)
At 6 months, the only available study found no benefit of spinal cord stimulation on back pain compared with placebo (1 trial, 50 participants; moderate-certainty evidence). At 6 months, participants given placebo treatment reported that their average pain was 61 points, and those given spinal cord stimulation reported that their pain was 4 points better (8.2 points better to 0.2 points worse).
Function (0 to 100, lower scores mean better function)
At 6 months, one study found no benefit of spinal cord stimulation on function (that is, people's general physical function) compared with placebo (1 trial, 50 participants; moderate-certainty evidence). Participants given placebo treatment reported that their functioning was 35.4 points at 6 months, and those given spinal cord stimulation reported that their functioning was 1.3 points better (3.9 points better to 1.3 points worse).
Health-related quality of life (0 to 1, higher scores mean better quality of life)
At 6 months, one study found no benefit from spinal cord stimulation on health-related quality of life compared with placebo (1 trial, 50 participants; moderate-certainty evidence). Participants given placebo treatment reported that their health-related quality of life was 0.44 points at 6 months, and those given spinal cord stimulation reported that their health-related quality of life was 0.04 points better (0.16 points better to 0.08 points worse).
Global assessment of efficacy (number of participants with a 50% improvement in pain or better)
None of the placebo-controlled studies measured this outcome.
Withdrawals due to adverse events (i.e. an unwanted event that causes harm)
We are uncertain whether spinal cord stimulation caused people to withdraw from studies due to adverse events because there were few studies and the evidence was based on only a few cases.
Adverse events (e.g. increased pain)
One study that followed people for 12 months found 9 participants (18%) experienced adverse events such as infections, damage to the spine or nerves, bladder problems, and movement of very small parts of the devices that deliver the electrical impulses to the spinal cord (known as 'lead migration').
Serious adverse events (e.g. an infection requiring hospitalisation)
Some studies reported serious adverse events in people receiving spinal cord stimulation that required repeated surgery. The only placebo-controlled study that followed people for 12 months found 4 participants (8%) required repeated surgery. In the five other studies of people receiving a new spinal cord stimulation implant, the number of people requiring repeat surgery, due to adverse events such as infection or device problems, ranged from 4.1% at 8 weeks to 30.9% at 24 months. However, it was not possible to estimate how common these events were compared with placebo or no treatment, as limited information was available.
Limitations of the evidence
For people with low back pain, we are moderately confident that, at 6 months, spinal cord stimulation probably does not lead to lower pain, better function, or higher quality of life compared with placebo. We are uncertain whether spinal cord stimulation can improve outcomes in the immediate term compared with placebo. Little to no information is available regarding long-term efficacy or the risk of side effects and complications.