EEG Changes and DNA Markers Related to taVNS in Stroke Patients: a Preliminary Study (StrokeVNS)

March 26, 2026 updated by: Caroline Schnakers, Casa Colina Hospital and Centers for Healthcare

EEG Changes and DNA Markers Related to Transcutaneous Auricular Vagus Nerve Stimulation (taVNS) in Acute Stroke Patients: a Preliminary Study

In the United States, more than 795,000 people have a stroke every year. Motor impairment after a stroke is common and can be debilitating. To date, there remain few treatments available to help improve motor recovery after a stroke, making this an important area of research. Novel use of neuromodulation such as Invasive Vagus Nerve Stimulation (VNS) has been shown to improve motor recovery in stroke patients. Vagus nerve stimulation (VNS), in which the nerve is stimulated with electrical pulses, has demonstrated success for a variety of conditions, including inflammation, depression, cognitive dysfunction, chronic fatigue, headaches/migraines, pain, insomnia, and cardiovascular issues. Very recently, non-invasive options have been developed and might be a promising alternative. The research in this area is still very limited and much more research is needed to investigate non-invasive/trancutaneous auricular vagus nerve stimulation (taVNS) related biomechanisms and to further support its efficacy in acute patients. The purpose of this study is to build upon the current research to investigate changes in electrical brain activity (using electrophysiology) and genetic markers related to improvements in both motor and cognitive recovery following the use of taVNS vs. sham in acute stroke patients.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

To date, there are only few treatments available to help improve recovery after a stroke. Vagus nerve stimulation (VNS) is FDA approved for the treatment of epilepsy, migraines, and refractory depression. However, there are many novel applications that are being actively researched and show great promise. One such application is to enhance neurologic recovery after stroke. Dawson et al performed a clinical trial that showed implanted VNS improved motor recovery in patients with upper extremity motor deficits following an ischemic stroke. Due to its invasive nature, implanted VNS is often viewed as an impractical option. An alternative is to stimulate the vagus nerve externally, thus avoiding surgery and surgical complications. One approach is transcutaneous auricular VNS (taVNS) at the tragus. This region of the external ear is partially innervated by the auricular branch of the vagus nerve, making it a good site for cutaneous stimulation. The tragus also offers some advantages in terms of ease of applying electricity to the anterior wall of the external ear canal by being able to clip onto the tragus. Furthermore, studies have shown that stimulation through the auricular canal causes activation of the vagus nerve pathway, comparable to direct stimulation of the nerve itself. Thus far, the available literature has focused mostly on patients with chronic stroke (>6 months) showing preliminary safety and efficacy for such technique. Time-window might be an important factor impacting treatment efficacy. Applying taVNS in acute patients where neural plasticity is still occurring in a stable but healing brain might be more impactful than in chronic patients where most of the damages have occurred and neural plasticity has slow down drastically. One double-blinded randomized controlled study by Li and co-workers (2022) in 60 acute stroke patients showed that combining taVNS with conventional rehabilitation improved safely the recovery of motor functions at follow-up (until one year post-treatment) as compared to sham. However, that study does not investigate the biomechanisms of such recovery. Understanding how taVNS changes neural functioning is nevertheless crucial in order to understand its mechanisms of action in the acute stage. In this study, electroencephalography (EEG) will be used since this technique is easily implementable in clinical settings and, since a substantial amount of research have linked EEG recordings at rest (e.g., delta to alpha power ratio) to later recovery after stroke. Previous research was also limited to assessing motor recovery and could benefit from a more holistic approach including the assessment of its impact on cognitive recovery. Our study will also use genetic markers. Indeed, genetic markers have been highlighted in more recent years as potentially yielding precious information on how predisposing factors related to brain structure and functioning can impact an individual's outcome. Prior research suggests that presence of DNA markers, such as brain-derived neurotrophic factor (BDNF), and/or catechol-O-methyltransferase (COMT) influence stroke patients' recovery (8-14). Specific BDNF polymorphisms can be associated with motor deficits (i.e., altered short-term plasticity and motor learning) (9, 11), while some of COMT polymorphisms can be associated with lower dopamine levels in the prefrontal cortex (12-13). Finally, taVNS sessions were given to acute patients while hospitalized over the course of 4 weeks while the average length of stay in the US is between 1 and 3 weeks depending on the severity of impairments in stroke patients. Therefore, this sham-controlled study will also assess if both motor and cognitive improvements can be obtained in stroke patients using a shorter time frame (2 weeks).

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
44

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • United States
    • California
      • Pomona, California, United States, 91769
        • Recruiting
        • Casa Colina Hospital and Centers for Healthcare
        • Contact:
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • First-time Cerebrovascular Accident (Ischemic or Hemorrhagic)
  • Within a month post-injury
  • Presence of motor impairments (FMA-U≤62)

Exclusion Criteria:

  • Advanced cardiac, pulmonary, liver, or kidney disease
  • Bradycardia (Resting HR < 60)
  • Presence of Apraxia, Aphasia or confusion
  • Other musculoskeletal or neurologic diseases that could interfere with the outcome measures
  • Previous surgical intervention on the vagus nerve
  • Participation in other clinical trials
  • Alcohol or drug abuse

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: TaVNS intervention
Before starting applying taVNS, patients will be assessed using the FMA-U and the mRS for motor recovery as well as the MOCA for cognitive recovery. Resting state EEG will be recorded with eyes open during 15 minutes using our 64 electrodes cap (actiCHamp Plus; brainproducts.com), just after the behavioral assessment is performed. On the same day, patients will receive taVNS for 45 minutes, during therapy. The stimulation parameters, will be as follows: 250ms square pulses at 20 Hz. The electrical stimulation will given for 45 minutes a day for 10 working days (5 days a week for 2 weeks). The amplitude will be 1.7mA but may be reduced to 1.0mA if the patient is unable to tolerate due to discomfort or pain. After the last taVNS session is applied, outcome measures will be administered again by the research team. A follow-up at 6 months after the end of the last session will be conducted over the phone using the adapted version of the mRS and the MOCA.
Device: Transcutaneous vagus nerve stimulation
The Parasym Plus device (https://parasym.io) is a transcutaneous auricular vagus nerve stimulator that has been deemed non-significant risk (NSR) by the FDA. Transcutaneous auricular vagus nerve stimulator is a non-significant risk device, as it involves electrical stimulation of the external ear using an ear clip, with no invasive components. The stimulation parameters will be limited to the confines of existing published data. tVNS is safe and well tolerated at doses tested in research studies. The Parasym device is considered low risk when used in accordance with the instructions for use. Participants will be properly trained to use the device, and those with contraindications will be excluded for extra precaution. A low incidence of skin irritation has been reported. No serious adverse events have been reported.
Sham Comparator: Sham Group
The sham procedure is identical to taVNS, except the device built-in sham setting will stop the stimulation gradually after one minute (this setting will be set by the research coordinator before starting the first session).
Device: Transcutaneous vagus nerve stimulation
The Parasym Plus device (https://parasym.io) is a transcutaneous auricular vagus nerve stimulator that has been deemed non-significant risk (NSR) by the FDA. Transcutaneous auricular vagus nerve stimulator is a non-significant risk device, as it involves electrical stimulation of the external ear using an ear clip, with no invasive components. The stimulation parameters will be limited to the confines of existing published data. tVNS is safe and well tolerated at doses tested in research studies. The Parasym device is considered low risk when used in accordance with the instructions for use. Participants will be properly trained to use the device, and those with contraindications will be excluded for extra precaution. A low incidence of skin irritation has been reported. No serious adverse events have been reported.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Resting state electroencephalogram (EEG)
Time Frame: within 24 hours before intervention and within 24 hours after the end of the intervention
Resting state electroencephalogram (EEG) will be recorded with eyes open during 15 minutes using our 64 electrodes cap (actiCHamp Plus; brainproducts.com). Spectral analysis will be performed on consecutive, artifact-free, epochs of awake EEG signal. The selected epochs will be filtered (1-70 Hz, 12 db/octave), followed by a 60 Hz notch filter to suppress the noise of the electrical power line, reformatted against the linked Cz reference. In order to remove blink-artifacts, we will apply an ICA-artifact rejection algorithm. Then, the selected EEG activity will be divided into non-overlapping 2 s segments and analyzed using the fast Fourier transform. Power spectral density (PSD) will be evaluated in the delta (1-4 Hz), theta (5-8 Hz), alpha (9-12 Hz), and beta (13-30 Hz) bands. Primary measure will nevertheless be PSD ratio of fast (alpha) to slow (delta) frequencies. Such ratios will be compared just before starting and just after the last taVNS session.
within 24 hours before intervention and within 24 hours after the end of the intervention
Fugl-Meyer Assessment - Upper extremity
Time Frame: within 24 hours before intervention and within 24hours after the end of the intervention
Fugl-Meyer Assessment for Upper extremity evaluates and measures recovery in post-stroke hemiplegic patients. The motor portion scores range from 0-66. The higher the score, the better the function.
within 24 hours before intervention and within 24hours after the end of the intervention
DNA Data
Time Frame: Sample to be taken at Day 1 of participation prior to taVNS treatment
Frequency of polymorphisms per marker (BDNF,COMT) will be estimated. These values will be used as a cofactor in a repeated measures 2x2 ANOVA framework with behavioral data as dependent variable, time as a within-subjects variable (pre/post) and group (taVNS, Sham) as a between subjects variable.
Sample to be taken at Day 1 of participation prior to taVNS treatment

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
The modified Rankin Scale
Time Frame: within 24 hours before intervention as well as within 24 hours and 6 months after the end of the intervention
The modified Rankin Scale is a commonly used scale for measuring the degree of disability or dependence in the daily activities of people who have suffered a stroke or other causes of neurological disability. Its scores range from 0 to 5 (lower scores reflecting better outcome). It has become the most widely used clinical outcome measure for stroke clinical trials and can be administered reliably over the phone.
within 24 hours before intervention as well as within 24 hours and 6 months after the end of the intervention
The Montreal Cognitive Assessment
Time Frame: within 24 hours before intervention as well as within 24 hours and 6 months after the end of the intervention
The Montreal Cognitive Assessment is a brief screening instrument originally designed to identify mild cognitive impairment in elderly patients attending a memory clinic. It is a 1-page test with scores ranging from 0 to 30 (higher scores reflecting better outcome), administrable in around 10 minutes, which evaluates different domains: visuospatial abilities, executive functions, short-term memory recall, attention, concentration, working memory, language, and orientation to time and space. This test has alternate versions that allow serial assessments and has been adapted to phone interview.
within 24 hours before intervention as well as within 24 hours and 6 months after the end of the intervention

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Casa Colina Hospital and Centers for Healthcare

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Foundation for Physical Medicine and Rehabilitation

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Elliott Block, MD, Casa Colina Hospital and Centers for Healthcare

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 29, 2024

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 30, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
January 10, 2024

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 23, 2024

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 26, 2024

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 31, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 26, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • Casa Colina

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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