Plasticity Biomarkers,Interleukin-6 and Motor Performance in Response to Vagus Nerve Stimulation After Stroke

Effect of Trans-auricular Vagus Nerve Stimulation on Plasticity Biomarkers,Interleukin-6 and Motor Performance Post Stroke : A Randomized Controlled Clinical Trial

Seventy-eight clinically verified Egyptian patients from both sexes with ischemic stroke that occurred at least 6 months to 2 years before inclusion will be randomly assigned into 2 groups, control group (GA) and the experimental group (GB). Patients will be randomly assigned into two equal groups: the control group (GA) and the experimental group (GB). Patients in the control group (GA) will be treated with sham Vagus nerve stimulation (taVNS) immediately before a selected physical therapy program, while in the experimental group (GB), patients will receive real transcutaneous auricular Vagus nerve stimulation (taVNS) followed by the same selected physical therapy program as (GA). Plasma level of Brain-Derived Neurotrophic Factors (BDNF) and Interleukin-6 (IL-6), Box and Blocks Test (BBT), and modified Ashworth scale (MAS) will be assessed at baseline and immediately post-treatment.

Background: Neuromodulation techniques play an integral role in restoring motor function in stroke patients by affecting the adaptive neuroplasticity and activation of neuromodulators that may reduce brain inflammation post stroke.

Objective: To assess the efficacy of transcutaneous auricular vagal nerve stimulation on plasma levels of Brain-Derived Neurotrophic Factors (BDNF), Interleukin-6 (IL-6), gross manual dexterity, and muscle tone in patients with ischemic stroke.

Materials and Methods: Seventy-eight clinically verified Egyptian patients from both sexes with ischemic stroke that occurred at least 6 months to 2 years before inclusion, aged 55 to 65 years, were recruited. Patients will be randomly assigned into two equal groups; control group (GA) and the experimental group (GB). Patients in the control group (GA) were treated with sham Vagus nerve stimulation (taVNS) immediately before a selected physical therapy program, while in the experimental group (GB), patients received real transcutaneous auricular Vagus nerve stimulation (taVNS) followed by the same selected physical therapy program as (GA). Plasma levels of Brain-Derived Neurotrophic Factors (BDNF), serum Interleukin-6 (IL-6) , Box and Blocks Test (BBT) and Modified Ashworth scale (MAS) were assessed at baseline and immediately post-treatment.

Results: There was a statistically significant improvement in BBT, plasma IL-18 level and BDNF in experimental group (GB) post-treatment (P< 0.05) with no change in MAS. There was no statistical significant difference in BBT, plasma Interleukin-6 (IL-6) and MAS in control group post treatment (P> 0.05). While, there is a statistically significant improvement in BDNF in the control group post treatment. A statistically significant improvement was observed of BBT and BDNF in the study group compared to the control group (P< 0.05). There was no statistical significant difference in MAS between study and control groups (P> 0.05).

Conclusions: Non-invasive VNS as an adjunct to conventional physical rehabilitation enhances neuroplasticity and improves upper limb motor ability after ischemic stroke, as well as reducing the stroke-induced inflammatory process, which may affect the disease prognosis.

Inclusion Criteria:

• Hemiparetic patients with ischemic middle cerebral artery stroke
• The duration of illness ranged from at least 6 months to 2 years after stroke.
• Patient's age ranged from 55 to 65 years, patients with unilateral upper limb motor function impairment.
• Patients able to transfer at least one block in Box and Blocks Test.
• Patients with sufficient cognitive abilities that enables them to understand and follow instructions.
• Spasticity of upper limb muscles ranged from (grade 1:2) according to Modified Ashworth scale.

Exclusion Criteria:

• Other neurological diseases that affect upper limb function other than stroke (e.g.: Multiple sclerosis, peripheral neuropathy, Parkinsonism….etc.).
• Hemorrhagic stroke
• Visual or auditory impairment affecting their ability to complete the testing.
• Cognitive impairment.
• Cardiovascular problems and pulmonary or kidney disorders
• Musculoskeletal disorders (e.g. scoliosis, kyphosis, severe arthritis…etc.)
• Severe spasticity (a Modified Ashworth Scale score ≥3).
• Patients with any taVNS contraindications such as previous surgical intervention on Vagus nerve.
• Low blood pressure (<100/60mmHg) or low heart rate (<60bpm) and or high blood pressure (>220/130 mmHg).
• Pacemaker or other implanted electrical device.
• Any current or past history of cardiovascular disorders
• Facial or ear pain
• Recent ear trauma .