Effect of Vagus Nerve Stimulation Via the Outer Ear on Motor and Cognitive Deficits After Ischemic Stroke

The goal of this clinical trial is to learn if transcutaneous auricular vagus nerve stimulation (taVNS) works to treat motor and neurocognitive deficits after ischemic stroke when applied within 30 days after onset of stroke.

The main questions it aims to answer are:

* Does tVNS improve motor deficits measured by the Fugl-Mayer assessment after ischemic stroke?
* Does tVNS ameliorate stroke-related cognitive impairment? Researchers will compare tVNS to a placebo (sham stimulation, i.e. an electrode is fixed on the ear without applying electrical impulses ) to see if tVNS works to treat motor and cognitive deficits after stroke .

Participants will:

* Receive tVNS or sham stimulation for 30 minutes 5 days a week during 5 weeks after ischemic stroke
* Receive smotor and cognitive training during the tVNS or sham stimulation
* Will take part on a standardized stroke rehabilitation program during the 5 weeks in a rehabilitation clinic.

Study participants will undergo pre-evaluation and receive information within the first 7 days after admission to the Rheinburg-Klinik (Visit 0). During these 7 days, study participants will be randomly (1:1) allocated to the intervention group (taVNS) or control group (sham-stimulation) and will be clinically examined (Visit 1). At Visit 2 (≤7 days after admission), baseline assessments will be performed. During the intervention period, (week 2 to 6 after admission), either taVNS or sham-stimulation will be conducted for 30 minutes per day at 5 days per week for 5 weeks, paired with cognitive and motor training. Participants will be blinded to treatment. Standardized rehabilitation measures according to the clinic standards will be performed in both groups during the study period. All study participants will be monitored by recording an ECG during intervention/sham-stimulation. Before and after intervention/sham-stimulation an EEG will be conducted. After intervention, i.e., at the end of week 6, the same assessments as at baseline will be repeated (Visit 3). A follow up visit will take place 6 months after intervention.

Eligibility Criteria:
Inclusion Criteria:

* Onset of stroke ≥15 days and ≤30 days after randomization
* Ischemic stroke in the anterior cerebral circulation detected by MR imaging or computer tomography
* National Institutes of Health Stroke Scale (NIHSS) score ≥3 points
* Montreal Cognitive Assessment (MoCA) score ≤ 26 points
* First ever stroke
* Right-handed
* Ability to participate in a standardized rehabilitation therapy
* Written informed consent signed by the subject or next kin

Exclusion Criteria:

* Age \< 18 years
* Pregnant and breastfeeding women
* Severe concomitant neurological (brain tumor, encephalitis, Parkinson disease, epilepsy prior to stroke onset) or mental disorders (psychiatric conditions such as schizophrenia, uncontrolled depression or bipolar disorder before stroke onset)
* Severe aphasia (i.e. unable to follow two-stage-commands)
* Pre-existing hemiparesis
* Documented history of dementia before index stroke
* Primary intracranial hematoma or subarachnoid hemorrhage
* Active implantable medical device (e.g., pacemaker, deep brain stimulator, cochlear implants, cerebral shunts)
* Metal cervical spine hardware or metallic implant near the stimulation site
* Modified Rankin scale (mRS) ≥ 2 prior to stroke onset
* Low heart rate (\< 60 bpm)
* Severe vision and hearing problems
* Alcohol and drug abuse
* Active post-stroke delirium, unable to cooperate
* Type 1 and 2 diabetes mellitus
* Sore and diseased skin of the auricle
* Patients receiving any therapy (medication or otherwise) at study entry that would interfere with VNS