NCT06335199

tVNS Responsiveness Testing With Pupil Size

Movement-Associated tVNS and Responsiveness Testing for Personalized Rehabilitation

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 21 (actual)
• Sponsor: Georgia Institute of Technology · Academic / Other
• Sex: All
• Age: 18 Years – 89 Years
• Healthy volunteers: Accepted

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.

Detailed description

Participants will wear surface electrodes on the outer ear on both sides and a finger device that monitors heart rate. The attachment sites are the tragus or the cymba concha (depending on the shape and size of the ear) for tVNS and the ear lobe for sham. The electrical current will have a pulse duration of 0.1 ms at 30 Hz with an intensity below the pain threshold or 5 milliamp, whichever is lower, for a duration of 0.5 s. The experimental stimulation intensity will be determined as just below the pain threshold. Participants will receive multiple blocks of unilateral and bilateral stimulations to the sham or tVNS electrodes at rest, during which their pupil size will be recorded. The order of unilateral/bilateral and sham/tVNS stimulation will be randomized.

Conditions

• Stroke

Interventions

Type	Name	Description
PROCEDURE	Unilateral Left tVNS stimulation	Electrical stimulation to the cymba concha or tragus (depending on the ear dimension) of the outer ear on the left side after successful trials.
PROCEDURE	Bilateral tVNS stimulation	Electrical stimulation to the cymba concha or tragus (depending on the ear dimension) of the outer ear on both sides after successful trials.
PROCEDURE	Unilateral Left Sham stimulation	Electrical stimulation to the earlobe of the outer ear on the left side after successful trials.
PROCEDURE	Bilateral Sham stimulation	Electrical stimulation to the earlobe of the outer ear on both sides after successful trials.
PROCEDURE	Unilateral Right tVNS stimulation	Electrical stimulation to the cymba concha or tragus (depending on the ear dimension) of the outer ear on the right side after successful trials.
PROCEDURE	Unilateral Right Sham stimulation	Electrical stimulation to the earlobe of the outer ear on the right side after successful trials.

Timeline

• Start date: 2024-11-14
• Primary completion: 2025-10-27
• Completion: 2025-10-27
• First posted: 2024-03-28
• Last updated: 2025-10-29

Locations

1 site across 1 country: United States