Although SCS is a well-established therapy, it remains for most people an end-of-line treatment and is in many cases not even offered to potential candidates. The high cost of the device, which is often in the range of $10,000–20,000, is a limiting factor, as are controversies about the clinical effect of the treatment. Major points of criticism include the heterogeneity of study designs, an unacceptable balance between responder rates and complications, the unknown role of the placebo effect, and heavy industry involvement in clinical trials4.

Not all people with chronic pain who are treated with SCS benefit from the therapy. However, with an average success rate of more than 50%, the therapy compares favourably to pharmaceutical therapies for neuropathic pain5, particularly considering that individuals eligible for treatment have previously failed numerous other interventions and generally have suffered pain for many years. The typically long delay before SCS initiation can result in more profound sensitization, irreversible pathophysiological changes and comorbidities. Individuals could potentially respond more favourably to SCS if the therapy was offered to them earlier in their treatment history than is current practice.

“an average success rate of more than 50%”

Despite great efforts, the parameters that predict a favourable SCS outcome are still unknown, but an attempt at establishing guideline consensus for patient referral and indications for implantation6 was published in 2020.

Although severe complications of SCS do occur, the rate is very low with contemporary implantation techniques3. Compared with pharmaceutical treatments including opioids, TCAs and anticonvulsants, which can have considerable adverse effects, a well-established SCS treatment does not have adverse effects per se.

A substantial scepticism towards SCS is derived from the apprehension that the treatment is merely a result of placebo effect. Placebo is, for obvious ethical reasons, difficult to account for when designing clinical studies on surgical interventions. In addition, SCS has traditionally evoked paraesthesia, rendering blinding of active treatment impossible. A counterargument to SCS effects being merely placebo is that since SCS is an end-of-line treatment employed in individuals following the failure of numerous other therapies, people prone to placebo effects should have responded to other therapies earlier. Moreover, an increasing number of studies with several years of follow-up have demonstrated sustainable results for a substantial proportion of individuals7.

The recent introduction of paraesthesia-free stimulation paradigms has enabled placebo-controlled trials. So far, the few published randomized placebo-controlled trials have provided some evidence that SCS is effective in reducing pain intensity when compared with a placebo intervention8. However, large methodological differences have caused substantial statistical heterogeneity in effect across studies8, and deviations from the recommended clinical application of SCS have limited external validity9.

Owing to the high cost of the SCS devices, most randomized controlled trials are industry sponsored and they often have direct industry involvement, which can increase the risk of biased outcomes10. Thus, there is an increasing demand from neuromodulation practitioners for industry-independent research. Independent studies with more innovative designs and incorporation of composite outcomes are imperative.