Noninvasive brain stimulations (NIBS) is being used more frequently on patients with neuropathic pain (NP), but there was debate over how well they work to treat the condition. For a study, researchers sought to assess NIBS’s impact on the pain and depressive symptoms experienced by NP patients.
A thorough literature search was done on MEDLINE, Embase, PsycINFO, PEDro, and CENTRAL from when the databases were created until June 2021. Included were randomized controlled trials contrasting NIBS with sham stimulation.
The criteria were satisfied by a total of 13 studies with 498 participants. The pooled analysis showed a significant difference between NIBS and sham stimulation in the improvement of pain rating post-treatment (SMD = -0.60; 95% CI: -1.00 to -0.20; P=0.004). Only transcranial direct current stimulation (tDCS) and high-frequency repetitive transcranial magnetic stimulation (H-rTMS) were associated with pain reduction among all types of NIBS, according to subgroup analysis (SMD = -0.38; 95% CI: -0.71 to -0.04; P=0.030; H-rTMS: -0.95; 95% CI: -1.85 to -0.04; P=0.040). The positive effects of NIBS were still present at the follow-up visit (SMD = -0.51; 95% CI: -0.79 to -0.23; P=0.000), however only H-rTMS was observed to significantly reduce patient pain scores in subgroup analyses (SMD = -0.54; 95% CI: -0.85 to -0.24; P=0.000). Additionally, overall NIBS failed to significantly reduce the symptoms of depression in NP patients compared to sham stimulation at either the post-treatment (SMD = -0.19; 95% CI: -0.39 to 0.01; P=0.061) or follow-up visit (SMD = -0.18; 95% CI: -0.45 to 0.10; P=0.22) visit.
The meta-analysis demonstrated that NIBS had an analgesic impact on individuals with NP, but no positive effect was shown in lowering concurrent depressive symptoms. The results suggested NIBS clinical applicability in NP patients.