Making Sense of Vagus Nerve Stimulation for Stroke

Abstract

Implantable vagus nerve stimulation, paired with high-dose occupational therapy, has been shown to be effective in improving upper limb function among patients with stroke and received regulatory approval from the US Food and Drug Administration and the Centers for Medicare & Medicaid Services. Combining nonsurgical and surgical approaches of vagus nerve stimulation in recent meta-analyses has resulted in misleading reports on the efficacy of each type of stimulation among patients with stroke. This article aims to clarify the confusion surrounding implantable vagus nerve stimulation as a poststroke treatment option, highlighting the importance of distinguishing between transcutaneous auricular vagus nerve stimulation and implantable vagus nerve stimulation. Recent meta-analyses on vagus nerve stimulation have inappropriately combined studies of fundamentally different interventions, outcome measures, and participant selection, which do not conform to methodological best practices and, hence, cannot be used to deduce the relative efficacy of the different types of vagus nerve stimulation for stroke rehabilitation. Health care providers, patients, and insurers should rely on appropriately designed research to guide well-informed decisions.

Neurorehabilitation with vagus nerve stimulation: a systematic review

“…We did not perform a meta-analysis due to high variability in the methods used for VNS, and our team considered it would not provide an accurate effect size ( 43 ). VNS experts expressed similar concerns about the inappropriateness of combining results from various stimulation methods, published in a commentary ( 41 ). Hence, we calculated the relative change in outcome measures to assess the efficacy of VNS therapy on the most widely used upper extremity motor outcome measure, the upper extremity Fugl-Meyer-Assessment (FMA-UE), separately for non-invasive and invasive studies utilizing methods in two recently published systematic review papers ( 42 , 44 ).…”

“…In one of the recently published systematic reviews on VNS in the stroke population (40), results from non-invasive and invasive studies were combined when the meta-analysis was performed. It is not ideal to combine study results from non-invasive and invasive VNS studies due to differences in methods of stimulation and mechanisms; the experts in the field of VNS expressed similar views on this review paper in a recent publication (41).…”