Non-invasive Brain Stimulation for Neuropathic Pain After Spinal Cord Injury: A Systematic Review and Network Meta-Analysis

Frontiers in Neuroscience, 2022 · DOI: 10.3389/fnins.2021.800560 · Published: February 11, 2022

Neurology Pain Management Rehabilitation

Simple Explanation

This study systematically reviews and analyzes the effectiveness of non-invasive brain stimulation (NIBS) techniques, specifically repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), for treating neuropathic pain (NP) following spinal cord injury (SCI). The study compares the effects of these two NIBS methods. Neuropathic pain after spinal cord injury is a common and challenging complication. Current drug treatments often fail to provide adequate relief or have significant side effects. NIBS offers a non-invasive alternative to regulate the excitability of the cerebral cortex using electric or magnetic fields. The analysis indicates that NIBS can effectively relieve NP after SCI, and rTMS appears to be more effective than tDCS in reducing pain scores. The suggested parameters for rTMS are 80–120% resting motion threshold and 5–20 Hz, while for tDCS, they are 2 mA and 20 min.

Study Duration

Not specified

Participants

507 patients

Evidence Level

Systematic Review and Network Meta-Analysis of RCTs

Key Findings

1
NIBS can reduce the pain score in patients with neuropathic pain after spinal cord injury. The meta-analysis showed that the pain score of the NIBS group was lower than that of the control group.
2
The network meta-analysis showed that the best probabilistic ranking of the effects of two different NIBS on the pain score was repetitive transcranial magnetic stimulation (rTMS) > transcranial direct current stimulation (tDCS).
3
NIBS can reduce the pain score during follow-up. The meta-analysis showed that the follow-up pain score of the NIBS group was lower than that of the control group

Research Summary

This systematic review and network meta-analysis evaluated the effect of non-invasive brain stimulation (NIBS) on neuropathic pain (NP) after spinal cord injury (SCI) and compared the effects of two different NIBS techniques: repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS). The study included 17 randomized controlled trials (RCTs) with a total of 507 patients. Meta-analysis showed that NIBS significantly reduced pain scores and follow-up pain scores compared to the control group. However, NIBS did not significantly improve depression scores. Network meta-analysis indicated that rTMS was more effective than tDCS in relieving pain. The review suggests specific parameters for rTMS (80–120% resting motion threshold, 5–20 Hz) and tDCS (2 mA, 20 min), but calls for more large-scale, high-quality RCTs to further explore the efficacy and mechanisms of NIBS for NP after SCI.

Practical Implications

Clinical Practice

NIBS, particularly rTMS, can be considered as a non-invasive therapeutic option for relieving neuropathic pain in patients with SCI.

Research

Future research should focus on conducting large-scale, multicenter, double-blind RCTs to validate the efficacy and optimize the parameters of NIBS for treating NP after SCI.

Treatment Parameters

Clinicians can consider using rTMS parameters of 80–120% resting motion threshold and 5–20 Hz, and tDCS parameters of 2 mA and 20 min, as suggested by the review.

Study Limitations

1
Small number of included studies.
2
Inability to determine the causal relationship between depression and pain improvement.
3
Lack of detailed description of specific random methods, allocation concealment, and blind methods in some included studies.

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