Stimulation Parameters Used During Repetitive Transcranial Magnetic Stimulation for Motor Recovery and Corticospinal Excitability Modulation in SCI: A Scoping Review

Frontiers in Human Neuroscience, 2022 · DOI: 10.3389/fnhum.2022.800349 · Published: April 7, 2022

Spinal Cord Injury Neurology Rehabilitation

Simple Explanation

Spinal Cord Injury (SCI) is defined as a traumatic or non-traumatic event affecting the spinal cord that results in sensory, motor, and autonomic deficits reducing independence and quality of life (QOL). Repetitive transcranial magnetic stimulation (rTMS) is a neuromodulatory intervention which has the potential to reinforce the residual spinal and supraspinal pathways and induce plasticity. The observed effects of rTMS on sensorimotor function and spasticity in SCI individuals are thought to be due mainly to the rTMS-induced changes in CSE and CS connectivity.

Study Duration

Not specified

Participants

16 published rTMS studies involving SCI individuals

Evidence Level

Scoping Review

Key Findings

1
Our review confirms previous work about the seeming effectiveness of HF-rTMS to promote motor improvements and CSE changes in SCI.
2
The effect of daily stimulation sessions over 1 week on spasticity symptoms was explored. A modulation and improvement of knee spasticity symptoms were demonstrated after 20 Hz-rTMS over the leg M1 on 15 iSCI participants
3
The effects on LE function and spasticity seem more significant and maintained when HF-rTMS is associated with other rehabilitation interventions.

Research Summary

Our review confirms previous work about the seeming effectiveness of HF-rTMS to promote motor improvements and CSE changes in SCI. All the group studies reported significant improvements for at least one of the outcomes considered. Most rTMS studies in SCI showed promising and lasting functional gains, associated or not with neurophysiological changes (Table 3). However, the relative novelty of the ﬁeld in SCI and the limited number of RCTs and the wide range of rTMS protocol design and parameters used precluded us, at this time, from performing a meta-analysis and drawing definite conclusions. The inter- and intra-individual variability in response to TMS and to NIBS, in general, is widely reported and studied in the literature. In able-bodied individuals, key influence factors were identified such as baseline MEP amplitude stimulus intensity and target muscle.

Practical Implications

Clinical Practice

rTMS is relatively easy to administer and well-tolerated intervention with promising beneficial effects on functional recovery after SCI.

Future Research

Future investigations may also focus on developing strategies to design individually-targeted rTMS interventions.

Protocol Design

More systematic use of neuronavigation and reporting of hotspot coordinates and rTMS induced electric fields during treatment may help increase the understanding and reproducibility of the effects observed.

Study Limitations

1
The relative novelty of the ﬁeld in SCI and the limited number of RCTs
2
The wide range of rTMS protocol design and parameters used precluded us, at this time, from performing a meta-analysis
3
The heterogeneity of outcome measures, the lack of RCTs and the inconsistent reporting of data and statistics (means and SDs) prevented us from performing a meta-analysis.

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