Noninvasive brain stimulation combined with exercise in chronic pain: a systematic review and meta-analysis

ABSTRACT

Background: The use of noninvasive brain stimulation (NIBS) combined with exercise could produce synergistic effects on chronic pain conditions. This study aims to evaluate the efficacy and safety of NIBS combined with exercise to treat chronic pain as well as to describe the parameters used to date in this combination.

Methods: The search was carried out in Medline, Central, Scopus, Embase, and Pedro until November 2019. Randomized clinical trials (RCTs) and quasi-experimental studies reporting the use of noninvasive brain stimulation and exercise on patients with chronic pain were selected and revised.

Results: The authors included eight studies (RCTs), reporting eight comparisons (219 participants). Authors found a significant and homogeneous pain decrease (ES: −0.62, 95% CI:-0.89 to −0.34; I2 = 0.0%) in favor of the combined intervention compared to sham NIBS + exercise, predominantly by excitatory (anodal tDCS/rTMS) motor cortex stimulation. Regarding NIBS techniques, the pooled effect sizes were significant for both tDCS (ES: −0.59, 95% CI: −0.89 to −0.29, I2 = 0.0%) and rTMS (ES: −0.76, 95% CI: −1.41 to −0.11, I2 = 0.0%).

Conclusions: This meta-analysis suggests a significant moderate to large effects of the NIBS and exercise combination in chronic pain. The authors discuss the potential theoretical framework for this synergistic effect.

KEYWORDS:

• Noninvasive brain stimulation
• chronic pain
• exercise
• transcranial direct current stimulation
• transcranial magnetic stimulation

Article Highlights

• The combination of NIBS and exercise has a moderate to large effect in chronic pain conditions.

• Common side effects were reported in both groups (active NIBS + exercise and sham NIBS + exercise). Two moderate-severe side effects were reported in the active NIBS + exercise.

• Exercise protocols included aerobic, strength, flexibility exercises. The description of the protocols were heterogenous, hence, future studies should considerer a description including, type, intensity, duration and frequency of the exercise protocol.

• The NIBS protocol for tDCS was almost homogeneous including the location of the electrodes and duration. For rTMS, two different protocols were described including rTMS and theta burst stimulation

• More factorial design studies are needed in order to confirm the efficacy of NIBS + exercise from exercise or NIBS alone.

Declaration of Interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer Disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Supplementary material

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Additional information

Funding

This work is supported by a NIH grant (1R01AT009491-01A1).