Combining Non-Invasive Vagus Nerve Stimulation and Robotic Training in Upper Limb-Impaired Chronic Stroke Patients

Combining Non-Invasive Vagus Nerve Stimulation and Robotic Training in Upper Limb-Impaired Chronic Stroke Patients

Combining Non-Invasive Vagus Nerve Stimulation and Robotic Training in Upper Limb-Impaired Chronic Stroke Patients

Biomedical Robotics and Biomicrosystems, Campus Bio-Medico University, Physical and Rehabilitation Medicine, Campus Bio-Medico University

Previous studies suggested that both robot-assisted rehabilitation and non-invasive vagus nerve stimulation can improve upper limb function in chronic stroke patients. Aim of present study is to explore whether the combination of these two approaches might enhance their positive effects on motor recovery. Safety and efficacy of this combination will be assessed within a proof-of-principle, double-blinded, randomized, sham-controlled trial. Transcutaneous vagus nerve stimulation (tVNS) will be delivered at left ear, in order to improve the response to the following robot-assisted therapy. Patients with both ischemic and hemorrhagic chronic stroke will be randomized to robot-assisted therapy associated with real or sham tVNS, delivered for 10 working days. Change in Fugl-Meyer has been chosen as primary outcome, while changes in several quantitative indicators of motor performance extracted by the robot as secondary outcomes.

ischemic stroke, hemorrhagic chronic, non-invasive vagus nerve stimulation, robot-assisted rehabilitation

This group receives SHAM VNS during robotic rehabilitation. Sham VNS is not effective. Both groups receive the same amount of robotic rehabilitation.

The stimulation of the auricular branch of the vagus nerve will be performed through an electric stimulator and two Ag-AgCl electrodes placed in the left external acoustic meatus at the inner side of the tragus. For sham stimulation, electrodes will be attached to the left ear lobe. tVNS will be delivered as trains lasting 30 s and composed by 600 pulses (intra-train pulse frequency = 20 Hz; pulse duration = 0.3 ms) repeated every 5 min for 60 min. The intensity of stimulation will individually adjusted to a level ranging above the detection threshold and below the pain threshold. In this range, when possible, the investigators will chose an intensity of 8 mA. Each day, for 10 consecutive working days, each patient will receive a session of robotic therapy during the real or sham tVNS stimulation

Inclusion Criteria: first-ever ischemic or hemorrhagic stroke at least 1 year earlier hand function impairment ability to give informed consent and comprehend instructions Exclusion Criteria: previous surgical intervention on vagus nerve low hearth rate (< 60 bpm) cognitive impairment or any substantial decrease in alertness, language reception, or attention that might interfere with understanding instructions for motor testing apraxia excessive pain in any joint of the paretic extremity advanced liver, kidney, cardiac or pulmonary disease history of significant alcohol or drug abuse depression or use of neuropsychotropic drugs such as antidepressants or benzodiazepines pregnant women