NCT06335199

Brief Summary

The goal of this study is to learn about the acute pupil response to transcutaneous vagus nerve stimulation (tVNS) in stroke survivors and healthy adults. The main question it aims to answer is whether pupil size response is greater with bilateral tVNS compared to unilateral tVNS. Participants will receive tVNS and sham at the outer ear unilaterally and bilaterally in resting condition. The pupil size of the participants will be recorded during tVNS.

Trial Health

87
On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
21

participants targeted

Target at below P25 for not_applicable stroke

Timeline
Completed

Started Nov 2024

Geographic Reach
1 country

1 active site

Status
completed

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

Click on a node to explore related trials.

Study Timeline

Key milestones and dates

First Submitted

Initial submission to the registry

March 15, 2024

Completed
13 days until next milestone

First Posted

Study publicly available on registry

March 28, 2024

Completed
8 months until next milestone

Study Start

First participant enrolled

November 14, 2024

Completed
12 months until next milestone

Primary Completion

Last participant's last visit for primary outcome

October 27, 2025

Completed
Same day until next milestone

Study Completion

Last participant's last visit for all outcomes

October 27, 2025

Completed
11 months until next milestone

Results Posted

Study results publicly available

September 14, 2026

Completed
Last Updated

September 14, 2026

Status Verified

March 1, 2025

Enrollment Period

12 months

First QC Date

March 15, 2024

Results QC Date

June 4, 2026

Last Update Submit

August 27, 2026

Conditions

Healthy AdultStroke

Outcome Measures

Primary Outcomes (2)

  • Peak Percent Change in Pupil Diameter During Stimulation

    For each stimulation trial, pupil diameter is recorded continuously. The outcome is the maximum percent change in pupil diameter during the stimulation period relative to the mean pupil diameter measured immediately before stimulation within the same trial.

    During one study visit (within 1 day)

  • Mean Percent Change in Pupil Diameter During Stimulation

    For each stimulation trial, pupil diameter is recorded continuously. The outcome is the mean percent change in pupil diameter during the stimulation period relative to the mean pupil diameter measured immediately before stimulation within the same trial.

    During one study visit (within 1 day)

Study Arms (1)

Repeated-Measures Stimulation Protocol

EXPERIMENTAL

All participants receive all six stimulation conditions: unilateral left sham, unilateral right sham, bilateral sham, unilateral left transcutaneous vagus nerve stimulation (tVNS), unilateral right tVNS, and bilateral tVNS. Each participant completes 12 blocks during a single testing session, with each block containing one trial of each of the six stimulation conditions. Twelve blocks with different predefined orders of the six conditions were established before testing began. For each participant, the order of the 12 predefined blocks is randomized. Thus, each participant receives each of the six stimulation conditions once per block and 12 times in total.

Procedure: Unilateral Left tVNS stimulationProcedure: Bilateral tVNS stimulationProcedure: Unilateral Left Sham stimulationProcedure: Bilateral Sham stimulationProcedure: Unilateral Right tVNS stimulationProcedure: Unilateral Right Sham stimulation

Interventions

Unilateral Left tVNS stimulationPROCEDURE

Electrical stimulation to the cymba concha and tragus of the outer ear on the left side.

Repeated-Measures Stimulation Protocol
Bilateral tVNS stimulationPROCEDURE

Electrical stimulation to the cymba concha and tragus of the outer ear on both sides.

Repeated-Measures Stimulation Protocol
Unilateral Left Sham stimulationPROCEDURE

Electrical stimulation to the earlobe of the outer ear on the left side.

Repeated-Measures Stimulation Protocol
Bilateral Sham stimulationPROCEDURE

Electrical stimulation to the earlobe of the outer ear on both sides.

Repeated-Measures Stimulation Protocol
Unilateral Right tVNS stimulationPROCEDURE

Electrical stimulation to the cymba concha and tragus of the outer ear on the right side.

Repeated-Measures Stimulation Protocol
Unilateral Right Sham stimulationPROCEDURE

Electrical stimulation to the earlobe of the outer ear on the right side.

Repeated-Measures Stimulation Protocol

Eligibility Criteria

Age18 Years - 89 Years
Sexall
Healthy VolunteersYes
Age GroupsAdult (18-64), Older Adult (65+)

You may qualify if:

  • years old across all races, genders, and ethnicities.
  • Post-stroke subjects will have persistent hemiparesis on the upper extremity (UE) with some residual UE voluntary movement.

You may not qualify if:

  • Able-bodied subjects:
  • Younger than 18 years old or older than 89 years old
  • Current or history of cardiac disease
  • Have a vision problem not corrected by glasses or contact lenses
  • Have an implanted device such as a neurostimulator or cochlear implant
  • Current or history of tympanic membrane perforation
  • Had a stroke or lesion (including tumor) in your brain
  • Had a head injury or brain surgery
  • Suffer from frequent or severe headaches
  • Had a fainting spell or syncope
  • Have any metal in the head such as shrapnel, surgical clips, or fragments from welding or metal work
  • Have any implanted device such as cardiac pacemakers, medical pumps, or intra-cardiac lines
  • Had any brain-related conditions (i.e. multiple sclerosis, Parkinson, Alzheimer)
  • Had any illness that caused brain injury (i.e. meningitis, aneurysm, brain tumor)
  • Had any head trauma that was associated with a loss of consciousness or diagnosed as a concussion
  • +25 more criteria

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (1)

Human Neuromuscular Physiology Lab

Atlanta, Georgia, 30318, United States

Location

MeSH Terms

Conditions

Stroke

Condition Hierarchy (Ancestors)

Cerebrovascular DisordersBrain DiseasesCentral Nervous System DiseasesNervous System DiseasesVascular DiseasesCardiovascular Diseases

Results Point of Contact

Title
Minoru Shinohara
Organization
Georgia Institute of Technology
shinohara@gatech.edu
(404) 894-2000

Study Officials

  • Minoru Shinohara, Ph.D.

    Georgia Institute of Technology

    PRINCIPAL INVESTIGATOR

Publication Agreements

PI is Sponsor Employee
No
Restrictive Agreement
No

Study Design

Study Type
interventional
Phase
not applicable
Allocation
NA
Masking
NONE
Purpose
BASIC SCIENCE
Intervention Model
SINGLE GROUP
Model Details: All participants receive all six stimulation conditions in a randomized order. The six conditions are unilateral left sham, unilateral right sham, bilateral sham, unilateral left transcutaneous vagus nerve stimulation (tVNS), unilateral right tVNS, and bilateral tVNS. The order of the six conditions is randomized independently for each participant.
Sponsor Type
OTHER
Responsible Party
SPONSOR

Study Record Dates

First Submitted

March 15, 2024

First Posted

March 28, 2024

Study Start

November 14, 2024

Primary Completion

October 27, 2025

Study Completion

October 27, 2025

Last Updated

September 14, 2026

Results First Posted

September 14, 2026

Record last verified: 2025-03

Data Sharing

IPD Sharing
Will share

De-identified individual participant data on pupil size change will be available to other researchers outside the primary research group.

Shared Documents
STUDY PROTOCOL, SAP, ICF
Time Frame
The data will become available after the publication of all papers from the study.
Access Criteria
The scientific data will be made available by a data repository after approval.

Locations

US(1)