Abstract
Background
Chronic pain is frequent in persons living with spinal cord injury (SCI). Conventionally, the pain is treated pharmacologically, yet long-term pain medication is often refractory and associated with side effects. Non-pharmacological interventions are frequently advocated, although the benefit and harm profiles of these treatments are not well established, in part because of methodological weaknesses of available studies.
Objectives
To critically appraise and synthesise available research evidence on the effects of non-pharmacological interventions for the treatment of chronic neuropathic and nociceptive pain in people living with SCI.
Search methods
The search was run on the 1st March 2011. We searched the Cochrane Injuries Group’s Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (OvidSP), Embase (OvidSP), PsycINFO (OvidSP), four other databases and clinical trials registers. In addition, we manually searched the proceedings of three major scientific conferences on SCI. We updated this search in November 2014 but these results have not yet been incorporated.
Selection criteria
Randomised controlled trials of any intervention not involving intake of medication or other active substances to treat chronic pain in people with SCI.
Data collection and analysis
Two review authors independently extracted data and assessed risk of bias in the included studies. The primary outcome was any measure of pain intensity or pain relief. Secondary outcomes included adverse events, anxiety, depression and quality of life. When possible, meta-analyses were performed to calculate standardised mean differences for each type of intervention.
Main results
We identified 16 trials involving a total of 616 participants. Eight different types of interventions were studied. Eight trials investigated the effects of electrical brain stimulation (transcranial direct current stimulation (tDCS) and cranial electrotherapy stimulation (CES); five trials) or repetitive transcranial magnetic stimulation (rTMS; three trials). Interventions in the remaining studies included exercise programmes (three trials); acupuncture (two trials); self-hypnosis (one trial); transcutaneous electrical nerve stimulation (TENS) (one trial); and a cognitive behavioural programme (one trial). None of the included trials were considered to have low overall risk of bias. Twelve studies had high overall risk of bias, and in four studies risk of bias was unclear. The overall quality of the included studies was weak. Their validity was impaired by methodological weaknesses such as inappropriate choice of control groups. An additional search in November 2014 identified more recent studies that will be included in an update of this review.
For tDCS the pooled mean difference between intervention and control groups in pain scores on an 11-point visual analogue scale (VAS) (0-10) was a reduction of -1.90 units (95% confidence interval (CI) -3.48 to -0.33; P value 0.02) in the short term and of -1.87 (95% CI -3.30 to -0.45; P value 0.01) in the mid term. Exercise programmes led to mean reductions in chronic shoulder pain of -1.9 score points for the Short Form (SF)-36 item for pain experience (95% CI -3.4 to -0.4; P value 0.01) and -2.8 pain VAS units (95% CI -3.77 to -1.83; P value < 0.00001); this represented the largest observed treatment effects in the included studies. Trials using rTMS, CES, acupuncture, self-hypnosis, TENS or a cognitive behavioural programme provided no evidence that these interventions reduce chronic pain. Ten trials examined study endpoints other than pain, including anxiety, depression and quality of life, but available data were too scarce for firm conclusions to be drawn. In four trials no side effects were reported with study interventions. Five trials reported transient mild side effects. Overall, a paucity of evidence was found on any serious or long-lasting side effects of the interventions.
Authors’ conclusions
Evidence is insufficient to suggest that non-pharmacological treatments are effective in reducing chronic pain in people living with SCI. The benefits and harms of commonly used non-pharmacological pain treatments should be investigated in randomised controlled trials with adequate sample size and study methodology.
Plain language summary
Treatments other than medication for people with chronic pain after spinal cord injury
Many people living with spinal cord injury (SCI) have chronic pain. Besides pain medication, other treatment possibilities are commonly offered. This systematic review aims to summarise available evidence on the effectiveness and possible side effects of other forms of treatment.
We searched electronic databases until March 2011 and found 16 randomised controlled trials with a total of 616 participants. We grouped these studies by type of treatment into eight groups: Eight studies were on brain stimulation, of which five used electronic and three magnetic stimulation. Three studies were on exercise programmes, two on acupuncture and one each on self-hypnosis, transcutaneous electrical nerve stimulation (TENS) and a cognitive behavioural programme. The included studies used a range of different methods to measure pain and other outcomes. Comparison groups also varied and included sham interventions, waiting lists and other pain treatments.
For any given type of intervention, only a few studies were found, and they included only small numbers of participants. Often the reported detail was insufficient. The overall quality of the studies was low. For instance, several studies used inappropriate comparison groups such as waiting lists. Consequently, the effectiveness of the treatments is uncertain. An additional search in November 2014 identified more recent studies that will be included in an update of this review.
For one type of treatment—transcranial direct current stimulation (tDCS)—results from two studies could be combined. The pooled results suggest that tDCS reduced pain in the short term and in the mid term. Also, exercise programmes for chronic shoulder pain provided pain relief. We found no evidence to suggest that repetitive transcranial magnetic stimulation (rTMS), cranial electrotherapy stimulation (CES), acupuncture, self-hypnosis or TENS is better than the respective control interventions for reducing chronic pain. Regarding outcomes other than pain, such as anxiety, depression or quality of life, as well as long-lasting side effects, no overall conclusions were possible, given that data were sparse. The included studies do not permit firm conclusions regarding whether treatments other than medication for chronic SCI pain are effective and safe. Trials with greater numbers of participants and improved study quality are needed to determine the effectiveness and safety of such treatments.
