Effect of Non-invasive Vagus Nerve Stimulation on Cerebrovascular Reactivity and Cognition in Chronic Stroke Patients

Stroke is a leading cause of disability worldwide, resulting in physical, cognitive, and emotional impairments. These impairments significantly affect individuals, families, and communities. It imposes a substantial social and financial burden on healthcare systems and economies. Deficits in cognitive functions are highly associated with reduced treatment outcomes after stroke. This interferes with social and occupational recovery and limit psychosocial functioning.

Introducing new therapeutic methods such as non-invasive vagus nerve stimulation (VNS) alongside traditional rehabilitation is essential for enhancing cognitive function after stroke. Vagus nerve stimulation can be invasive or non-invasive. 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.

There are few key human studies that assessed the effects of transcutaneous vagus nerve stimulation (tVNS) on cerebrovascular reactivity (CVR) and cognition in chronic stroke patients. Up to our knowledge, this is the first Egyptian study that will assess the effect of transcutaneous vagus nerve stimulation on cerebrovascular reactivity and cognition in chronic stroke patients. This study will hopefully be of benefit in the physical therapy field. This may guide rehabilitation programs of physical therapy toward better results.

Inclusion criteria

• Forty chronic ischemic hemiparetic patients, of both sexes, will represent the sample.
• The patient's age will range from 50 to 60 years old.
• Duration of illness will range from six months to twelve months.
• Patients with mild cognitive impairment according to Montreal Cognitive Assessment (MoCA) scale (from 18 to 25).
• Spasticity will be 1 or 1+ according to Modified Aschworth scale.
• Educated patients.

Exclusion criteria

• The patients will be excluded if they have one of the followings:
• Patients with other neurological disease that affect cognition.
• Visual, verbal or hearing impairments that can interfere with communication.
• Depression assessed by Hamilton Depression Scale (Ham-D).
• Patients with poor bone window.
• History of psychiatric disease.
• Hemorrhagic stroke patients.
• Uncontrolled blood pressure or low heart rate.
• Uncontrolled diabetes (>130 mg/dL especially if consistently over 150 to 160 mg/dL)
• Patients with any taVNS contraindications (open heart surgery, pacemaker or other implants, previous surgical intervention on Vagus nerve, Facial or ear pain, and recent ear trauma)
• Stroke patients with severe cognitive impairment.
• Uncooperative patients.