The Effectiveness of Low-Intensity Focused Ultrasound Stimulation of the Vagus Nerve in Ischemic Stroke - A Preliminary Study Based on a Rat Model.

Ischemic stroke has become one of the leading causes of global mortality and disability. Vagus nerve stimulation (VNS) is a novel approach for post-stroke motor rehabilitation. Electrical VNS has demonstrated neuroprotective and neuroplasticity-promoting effects in ischemic stroke, and the effect of vagus nerve stimulation with low-intensity focused ultrasound (LIFUS) on improving motor function after stroke has also generated widespread interest. The aim of this study is to explore the effectiveness of ultrasound vagus nerve stimulation in improving motor function after stroke, based on a rat stroke model. This study utilized a middle cerebral artery occlusion (MCAO) rat model. Twelve ischemic rats were randomly assigned to an experimental group (n=6) receiving 15-minute daily LIFUS stimulation of the left vagus nerve for seven days and a sham-stimulated control group (n=6). Neural cell viability and infarct volume were assessed via 2,3,5-triphenyltetrazolium chloride (TTC) staining, and forelimb grip strength was measured using a small animal grip strength tester. Preliminary findings indicated that LIFUS reduced the spread of ischemic lesions in the subacute phase (LIFUS: 12%, CON: 28%, P = 0.003) and enhanced ipsilateral forelimb grip strength (LIFUS: 7.82±0.75, CON: 5.52±0.54, p = 0.038), suggesting improved corticomuscular connectivity in the injured hemisphere.This study provides initial evidence that LIFUS-mediated vagus nerve stimulation promotes motor function recovery after ischemic stroke, supporting its potential clinical translation as a non-invasive neuromodulatory therapy.