tVNS in Stroke: A Narrative Review on the Current State and the Future

Abstract

Ischemic stroke is a leading cause of disability and there is a paucity of therapeutic strategies that promote functional recovery after stroke. Transcutaneous vagus nerve stimulation (tVNS) has shown promising evidence as a tool to reduce infarct size in animal models of hyperacute stroke. In chronic stroke, tVNS paired with limb movements has been shown to enhance neurological recovery. In this review, we summarize the current evidence for tVNS in preclinical models and clinical trials in humans. We highlight the mechanistic pathways involved in the beneficial effects of tVNS. We critically evaluate the current gaps in knowledge and recommend the key areas of research required to translate tVNS into clinical practice in acute and chronic stroke.

Making Sense of Vagus Nerve Stimulation for Stroke

“…While there is growing nonhuman data to characterize the underlying neurobiology of taVNS for stroke rehabilitation, thus far, there is considerable variation in the protocols used in the published clinical studies of taVNS on people with chronic stroke. 35 We assert that the meta-analyses discussed are not adequate to condone or refute transcutaneous stimulation of the skin of the ear as equivalent or superior to iVNS, and future primary clinical studies, as well as appropriately designed meta-analyses, are needed to resolve this question.…”

The evolution of neuromodulation for chronic stroke: From neuroplasticity mechanisms to brain-computer interfaces

“…Potential indications include cognitive enhancement, sensory restoration, and possible use in cases of hemorrhagic stroke [ [24] , [25] , [26] , [27] , [28] , [29] ]. Interestingly, the ability to modulate the vagus nerve non-invasively (i.e., trans -auricularly) to achieve the same motor improvements without surgery is also being intensively explored [ [30] , [31] , [32] , [33] ]. Altogether, as both the role and mechanism of neuroplasticity in post-stroke recovery has become better understood, the potential for patients suffering from stroke to experience significant recovery with neuromodulation of the vagus nerve has come into sharper focus.…”

Update on Non-invasive Brain Stimulation on Stroke Motor Impairment: A Narrative Review

“…The use of VNS in stroke is based on the principle of modulating neurons in the motor cortex via the activation of noradrenergic, cholinergic, and serotonergic systems, influencing the release of various neurotransmitters [ 22 23 ]. VNS can be used both invasively and noninvasively, with invasive VNS having received approval from the US Food and Drug Administration to treat moderate to severe upper extremity motor deficits associated with chronic ischemic stroke [ 22 ]. However, due to the potential side effects related to device implantation surgery, such as vocal cord palsy [ 24 ], clinical trials of non-invasive VNS have been proposed.…”