The Supplementary/Pre-Supplementary Motor Area as a target for TMS Neuromodulation-A Systematic Review.

Source: European Stroke Journal. Conference: European Stroke Organisation Conference, ESOC 2021. Virtual. 6(1 SUPPL) (pp 468), 2021.

Date of Publication: 2021.

Authors: Nazarova M.; Germanova K.; Novikov P.; Nikulin V.

Background and Aims:
The supplementary motor area (SMA) is a multifunctional brain area involved in motor and cognitive processes, which are often affected after stroke. The SMA is considered a promising target for non-invasive brain stimulation (NIBS) in various neuropsychiatric disorders. However, there is no well established protocol for this purpose. We systematically reviewed studies involving repetitive transcranial magnetic stimulation (rTMS) applied over the SMA/pre-SMA in healthy and clinical populations.

Method(s): We included 92 studies in the qualitative analysis, performed using narrative textual synthesis. Three studies were included in metaanalysis, performed in RStudio.

Result(s): Equal amount of studies was performed in healthy and clinical populations. Main processes modulated by rTMS over the SMA in healthy volunteers were: movement initiation and cessation, memorizing and execution of sequences, language processing and emotion recognition. The pre-SMA was shown to be involved in movement cessation and emotion recognition. As a therapeutic tool SMA rTMS was applied in Parkinson’s disease, obsessive-compulsive disorder (OCD), Tourette syndrome and other conditions. Pre-SMA rTMS was primarily used in OCD, and this category of studies was the only one suitable for quantative analysis. Three papers were included in meta-analysis, OCD symptoms tended to decrease more after 2 weeks of pre-SMA 1 Hz rTMS compared to sham (p-value=0.0942).

Conclusion(s): Our results demonstrated that the SMA/pre-SMA is a promising target for NIBS in a wide range of pathological conditions from movement disorders to psychiatry, allowing to consider it a possible target in stroke as well. More research is needed to define interhemispheric and SMA/pre-SMA functional differences.