Effect of Transcutaneous Vagus Nerve Stimulation on Upper Limb Function in Stroke Patients

The goal of this interventional study is to investigate the therapeutic efficacy of non-invasive vagus nerve stimulation on upper limb function in chronic stroke patients . The main question is:

•Is there a significant effect of non-invasive vagal nerve stimulation on upper limb motor function in stroke patients? Participants will be assigned into two groups. They will receive 12 sessions of true or sham transcutaneous auricular vagus nerve stimulation for 30 minutes immediately followed by 30 minutes of selected physical therapy program, three sessions per week for four weeks.

Stroke causes several neurological deficits or impairments as hemiparesis, communication disorders, cognitive deficits or disorders in visuo-spatial perception. Approximately 60% of survivors after stroke suffer from upper limb motor impairment, which lead to loss of independence with poor quality of life. These global economic and social costs of chronic disability due to stroke necessitate the development of new methods beside the conventional treatment to induce neuroplasticity in stroke recovery.Vagus nerve stimulation (VNS) is a neuromodulation therapy, which sends impulses into the neural center to generate corresponding nervous activity. Vagus nerve stimulation is an established treatment in epilepsy, depression, chronic tinnitus, migraine and chronic pain.Vagus nerve stimulation can be invasive or non-invasive. Invasive VNS requires the implantation of a programmable device and electrodes that directly stimulate afferents of the vagus nerve under general anesthesia. Non-invasive method of VNS via transcutaneous stimulation of the peripheral auricular branch of the vagus nerve (taVNS) is safer, better-tolerated method for delivering VNS with the same effect of invasive VNS.

Eligibility Criteria:
Inclusion Criteria:

* Hemiparetic patients with ischemic middle cerebral artery stroke.
* Duration of illness ranged from at least 6 months after stroke.
* The patient's age ranged from 45 to 65 years.
* Spasticity of upper limb muscles ranged from (grade 1:2) according to the Modified Ashworth scale.
* The patients with unilateral upper limb motor function impairment.
* Patients with sufficient cognitive abilities that enable them to understand and follow instructions.

Exclusion Criteria:

* Patients with neurological diseases that affect upper limb function other than stroke (e.g.: Multiple sclerosis, Peripheral neuropathy, Parkinsonism....etc.).
* Hemorrhagic stroke patients.
* Patients with previous surgical intervention on the vagus nerve.
* Patients with pacemakers or other implanted electrical devices.
* Patients with a history of significant alcohol or drug abuse.
* Patients with musculoskeletal disorders such as severe arthritis, knee surgery, total hip joint replacement, lower limb fractures or contractures of fixed deformity, and leg length discrepancy after total hip replacement.
* Patients with cardiovascular problems (unstable angina, recent myocardial infarction, congestive heart failure, significant heart valve dysfunction, or unstable hypertension) or pulmonary or kidney disorders.
* Patients with visual or auditory impairment affecting their ability to complete the testing.
* Patients with cognitive impairment.
* Any current or past history of facial or ear pain, recent ear trauma, or metal implants above the level of the neck.