Non-invasive Auricular Vagus Nerve Stimulation (taVNS) on Postural Control and Autonomic Responses in Stroke

Effects of Non-invasive Auricular Vagus Nerve Stimulation (taVNS) on Postural Control and Autonomic Responses in Stroke Patients

This randomized controlled trial is conducted to determine the effects of transcutaneous auricular Vagus nerve stimulation (taVNS) on postural control in stroke patients (e.g., improvements in balance, mobility, and functional stability) and to evaluate the effects of taVNS on autonomic nervous system responses in stroke patients (e.g., changes in heart rate variability, blood pressure variability, skin conductance, and temperature).

Study Overview

• Status: Not yet recruiting
• Conditions: Stroke
• Intervention / Treatment: Other: Vagus Nerve Stimulation + Balance Training Group; Other: Balance Training Group

Detailed Description

Stroke remains one of the leading causes of long-term disability worldwide, impacting millions of individuals each year. Beyond motor and cognitive deficits, stroke survivors often experience significant impairments in postural control and autonomic nervous system (ANS) regulation, both of which are essential for functional independence and overall quality of life. Impaired balance increases the risk of falls, while autonomic dysfunction-manifesting as irregular heart rate variability (HRV), blood pressure variability (BPV), and abnormal skin conductance and temperature-can lead to complications affecting cardiovascular stability and daily functioning.

Traditional rehabilitation approaches primarily focus on physical therapy to improve movement and strength; however, interventions that target neuromodulation and autonomic regulation are still underutilized in post-stroke care. This gap opens the door for novel, non-invasive techniques that can enhance neural recovery and improve both motor control and autonomic function.

Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive method that stimulates the auricular branch of the vagus nerve through external electrodes placed on parts of the ear, typically the tragus or cymba conchae. The vagus nerve is a critical component of the parasympathetic nervous system and plays a key role in maintaining autonomic balance, inflammatory regulation, and neuroplasticity. By stimulating the vagus nerve, taVNS is believed to influence brain regions associated with motor control, cardiovascular regulation, and arousal-including the nucleus tractus solitarius (NTS), locus coeruleus, thalamus, and insula.

Recent studies have shown that taVNS may enhance post-stroke recovery by promoting cortical reorganization, reducing neuroinflammation, and improving neural connectivity. It has also been found to modulate HRV and BPV, reflecting improvements in autonomic nervous system activity, and may contribute to better cardiovascular health and stress resilience. This randomized controlled trial aims to explore the therapeutic potential of taVNS in improving postural control and autonomic responses in patients recovering from stroke. Participants will receive taVNS using clinically standardized stimulation parameters (e.g., 25 Hz frequency, 250 μs pulse width, up to 6 mA intensity) administered for 30 minutes daily over 4 weeks. Postural outcomes will be evaluated using validated tools such as the Berg Balance Scale (BBS), Postural Assessment Scale for Stroke Patients (PASS), and Fugl-Meyer Assessment for Lower Extremities (FMA-LE). Autonomic responses will be assessed through heart rate variability, blood pressure variability, skin conductance, and skin temperature monitoring.

This study is significant because it addresses an important gap in stroke rehabilitation: the lack of non-invasive, targeted interventions that simultaneously improve both balance and autonomic function. By evaluating the dual impact of taVNS on these domains, this research has the potential to inform future stroke rehabilitation protocols, contributing to more holistic, patient-centered care. If effective, taVNS may offer a low-cost, portable, and easily integrated adjunct to conventional therapy, especially in low-resource settings or for patients with limited access to specialized care. In summary, this study investigates whether taVNS can serve as an effective tool to support postural stability and autonomic regulation in stroke survivors ultimately aiming to enhance recovery outcomes, reduce fall risk, and improve quality of life.

• Study Type: Interventional
• Enrollment (Estimated): 22
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Arshad Nawaz Malik, PhD Rehab; Phone Number: 03334503754; Email: Arshad.nawaz@riphah.edu.pk

Study Locations

• Pakistan
  • Punjab Province
    • Islamabad, Punjab Province, Pakistan, 44000
      • Railway General Hospital, Rawalpindi
      • Contact: Arshad Nawaz Malik, PhD Rehab; Phone Number: 03334503754; Email: Arshad.nawaz@riphah.edu.pk
      • Sub-Investigator: Abrish Habib Abbasi, Phd* Rehab
      • Principal Investigator: Hajra Arshad, MS-NMPT*

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Age between 18 to 70years who are diagnosed with ischemic brain injury, intracerebral hemorrhage shown by magnetic resonance imaging, or computed tomography.
• First occurrence of stroke characterized by a unilateral lesion, with an onset time (acute/ subacute) < 6 months
• With balance impairment (BBS Score = 21-44);
• no or mild spasticity on the lower-limb assessed by Modified Ashworth Scale (MAS ≤ 2);
• sufficient cognition to follow the instructions provided by the therapists and the computer.

Exclusion Criteria:

• Individuals exhibiting unstable vital signs, consciousness disorders, or an inability to cooperate with examination and treatment procedures
• Those with a heart rate below 60 beats per minute, or with implantable devices such as pacemakers or cochlear implants.
• Other medical or psychological conditions affecting participation

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Vagus Nerve Stimulation + Balance Training; Participants in the experimental group will receive transcutaneous auricular vagus nerve stimulation (taVNS) administered according to standardized clinical protocols. No intervention is provided at baseline, aside from initial assessments. During Weeks 1 and 2, taVNS will be applied daily or as per a specified schedule. The stimulation parameters include: application at the auricular site (such as the tragus), with a frequency of 25 Hz, pulse width of 250 µs, and intensity adjusted to individual tolerance, not exceeding 6 mA. Each session will last for 30 minutes. The same taVNS protocol continues through Weeks 3 and 4. This group will not perform physical balance exercises during the taVNS phase, focusing solely on neuromodulation through vagus nerve stimulation.	Other: Vagus Nerve Stimulation + Balance Training Group; Participants in the experimental group will receive transcutaneous auricular vagus nerve stimulation (taVNS) administered according to standardized clinical protocols. No intervention is provided at baseline, aside from initial assessments. During Weeks 1 and 2, taVNS will be applied daily or as per a specified schedule. The stimulation parameters include: application at the auricular site (such as the tragus), with a frequency of 25 Hz, pulse width of 250 µs, and intensity adjusted to individual tolerance, not exceeding 6 mA. Each session will last for 30 minutes. The same taVNS protocol continues through Weeks 3 and 4. This group will not perform physical balance exercises during the taVNS phase, focusing solely on neuromodulation through vagus nerve stimulation.
Active Comparator: Balance Training; Participants in the control group will also undergo baseline assessments without intervention. During Weeks 1 and 2, they will participate in daily or scheduled 30-minute balance training sessions, consisting of 14 basic exercises such as sit-to-stand, tandem stance, and single-leg stance. These exercises are designed to improve static and dynamic balance, and are tailored to the individual's ability and safety level. In Weeks 3 and 4, the balance training progresses in difficulty. This includes increasing repetitions or duration, adding dual-task challenges (like cognitive tasks while balancing), and incorporating tools like foam pads or wobble boards to increase instability and challenge postural control. Each session remains 30 minutes in length and is supervised for safety and consistency.	Other: Balance Training Group; Participants in the control group will also undergo baseline assessments without intervention. During Weeks 1 and 2, they will participate in daily or scheduled 30-minute balance training sessions, consisting of 14 basic exercises such as sit-to-stand, tandem stance, and single-leg stance. These exercises are designed to improve static and dynamic balance, and are tailored to the individual's ability and safety level. In Weeks 3 and 4, the balance training progresses in difficulty. This includes increasing repetitions or duration, adding dual-task challenges (like cognitive tasks while balancing), and incorporating tools like foam pads or wobble boards to increase instability and challenge postural control. Each session remains 30 minutes in length and is supervised for safety and consistency

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Berg Balance Scale (BBS)	A clinical tool used to assess static and dynamic balance through 14 functional tasks. Tasks include sitting, standing, reaching, turning, and single-leg stance. It evaluates a person's ability to maintain balance during common daily activities and helps determine the risk of falls, especially in stroke patients and older adults. Scoring: Each item is scored from 0 to 4 (maximum score: 56); Low fall risk: 41-56; Moderate fall risk: 21-40; High fall risk: 0-20	4 Weeks
Timed Up and Go Test (TUG)	A simple test used to assess mobility, balance, walking ability, and fall risk. The participant is timed while standing up from a chair, walking 3 meters, turning around, walking back, and sitting down. Scoring: Time recorded in seconds; <10 sec: Normal mobility; 10-20 sec: Good mobility, mostly independent; >20 sec: Limited mobility, may require assistance	4 Weeks
Postural Assessment Scale for Stroke Patients (PASS)	A stroke-specific tool used to assess postural control in lying, sitting, and standing positions. It includes 12 items that evaluate the ability to maintain or change postures. Scoring: Each item scored 0-3 (Total score: 36) Higher scores indicate better postural control.	4 Weeks
Fugl-Meyer Assessment - Lower Extremity (FMA-LE)	A quantitative measure to assess motor recovery of the lower extremities in post-stroke patients. Evaluates reflexes, movement, coordination, and joint function. Scoring: Each item scored on a 3-point scale (0 = cannot perform, 2 = performs fully) • Maximum score: 34 for lower extremity	4 Weeks
Heart Rate Variability (HRV)	A measure of the variation in time between heartbeats, reflecting autonomic nervous system activity, especially parasympathetic function. Scoring: Time-domain and frequency-domain indices (e.g., RMSSD, LF/HF ratio) Higher HRV = better autonomic flexibility.	4 Weeks
Blood Pressure Variability (BPV)	Evaluates variations in blood pressure over time, indicating autonomic regulation and cardiovascular stability. Scoring: Standard deviation (SD), coefficient of variation (CV), or spectral analysis • Abnormal variability may reflect autonomic dysfunction	4 Weeks
Skin Conductance and Skin Temperature	Measures sweat gland activity and peripheral temperature, indicating sympathetic nervous system activity.• Increased skin conductance = higher sympathetic arousal • Changes in skin temperature may reflect vasoconstriction/dilation	4 Weeks

Collaborators and Investigators

• Sponsor: Riphah International University
• Investigators: Principal Investigator: Hajra Arshad, MS-NMPT*, Riphah International Unversity

Study record dates

Study Major Dates

• Study Start (Estimated): May 20, 2026
• Primary Completion (Estimated): October 20, 2026
• Study Completion (Estimated): November 20, 2026

Study Registration Dates

• First Submitted: June 1, 2026
• First Submitted That Met QC Criteria: June 1, 2026
• First Posted (Actual): June 5, 2026

Study Record Updates

• Last Update Posted (Actual): June 5, 2026
• Last Update Submitted That Met QC Criteria: June 1, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Balance; Stroke rehabilitation; Postural control; Transcutaneous auricular vagus nerve stimulation; Autonomic functions
• Additional Relevant MeSH Terms: Cerebrovascular Disorders; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Vascular Diseases; Cardiovascular Diseases; Stroke; Therapeutics; Electric Stimulation Therapy; Vagus Nerve Stimulation
• Other Study ID Numbers: 02268 / Hajra Arshad

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No