Neurostimulation as a potential modality for transitioning patients with chronic refractory pain syndromes off opioid analgesics: A systematic review

Abstract

Opioid analgesics are mu-opioid agonists used in practice for pain management which pose significant health risks including, but not limited to, abuse, dependence, respiratory depression, overdose, and death. Medical devices such as spinal cord stimulators (SCS) – which fall under the category of neurostimulators – may offer an alternative method for pain management. Four searches were conducted on PubMed and the Cochrane Trials database to assess the effects neurostimulation has on opioid consumption. Sixty-two (62) unique results originally populated, and six studies out of the 62 results met inclusion criteria. One result was a neurophysiological study which found transcranial magnetic stimulation (TMS) decreased mu-opioid receptor availability (P < 0.001), thereby suggesting TMS may activate the release of endogenous opioids. Five results were clinical studies utilizing SCS for chronic pain. These five studies cumulatively enrolled 330 participants, 57 of which were withdrawn and 139 of which were using opioids at the time of enrollment. Following neurostimulation, 41% of participants discontinued opioid use altogether, 26.6% of participants decreased opioid use, 26.6% of participants remained on the same opioid dose, and 5.8% of participants increased opioid use. Overall opioid use decreased by an estimated 45.6% ± 13 following SCS. The median trial duration was 1 year, and the median sample size was 23 participants. Although the results unanimously showed effectiveness for pain control and opioid dose reductions, the studies in this review were small, and none were placebo-controlled. The statistical fallbacks of the five SCS studies make it difficult to draw concrete conclusions. More research is needed to ascertain the risk-benefit profiles of neurostimulators in chronic pain patients.