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NCT Number: NCT07173400

Effects of Transcutaneous Auricular Vagus Nerve Stimulation on Symptom Severity, Sleep Quality, Central Sensitization, and Kinesiophobia in Fibromyalgia

Fibromyalgia is a chronic condition characterized by widespread musculoskeletal pain, fatigue, sleep disturbances, and sensitivity to touch. Current treatments often provide only partial relief. This study evaluates a non-invasive technique called transcutaneous auricular vagus nerve stimulation (TaVNS), which delivers gentle electrical impulses to a part of the ear connected to the vagus nerve. The vagus nerve plays an important role in regulating pain, stress, and autonomic body functions such as sleep.

In this randomized controlled pilot trial, participants with fibromyalgia are assigned to receive either active TaVNS or sham (placebo) stimulation for 30 minutes per day, five days per week, over a four-week period. Participants are followed for a total of 8 weeks. The investigators will assess outcomes including pain intensity, sleep quality, central sensitization, and fear of movement (kinesiophobia).

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Key information

Conditions

Fibromyalgia (FM) Chronic Pain Fibromyalgia Muscular Diseases Musculoskeletal Diseases Nervous System Diseases Neurologic Manifestations Neuromuscular Diseases Pain Pathological Conditions, Signs and Symptoms Rheumatic Diseases Signs and Symptoms

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Istanbul Medipol University, Faculty of Medicine, Department of Physical Medicine and Rehabilitation

Istanbul, Bagcılar, 34815, Turkey (Türkiye)

About this study

Fibromyalgia (FM) is a chronic pain syndrome associated with widespread musculoskeletal pain, fatigue, sleep disturbances, and autonomic dysregulation. Current treatments provide only partial relief, highlighting the need for novel therapeutic approaches.

Rationale:

The vagus nerve is a key regulator of autonomic and inflammatory processes. Transcutaneous auricular vagus nerve stimulation (TaVNS) is a non-invasive technique that can modulate vagal activity through electrodes placed on the external ear, offering a potential alternative to surgically implanted vagus nerve stimulators.

Study Design:

This is a randomized, sham-controlled pilot trial conducted at Istanbul Medipol University. Thirty participants with fibromyalgia are randomized in a 1:1 ratio to receive either active TaVNS or sham stimulation.

Intervention:

Device: VagusStim® (Vagus Medical Technologies, Istanbul, Türkiye; CE-marked).

Electrode placement: left cymba concha (active group) vs. left earlobe (sham group).

Stimulation parameters: frequency 1-30 Hz, pulse width 50-250 μs, current intensity individually adjusted (0.1-36 mA) to each participant's sensory threshold.

Schedule: 30 minutes per day, 5 days per week, for 4 consecutive weeks (20 sessions total).

Supervision: All sessions are clinician-supervised.

Outcome Measures:

Primary outcomes:

Pittsburgh Sleep Quality Index (PSQI) - subjective sleep quality.

Fibromyalgia Impact Questionnaire (FIQ) - disease severity and functional impact.

Central Sensitization Inventory (CSI) - symptoms related to central sensitization.

Secondary outcomes:

Visual Analog Scale (VAS) - pain intensity.

Tampa Scale for Kinesiophobia (TSK) - fear of movement.

Symptom Severity Scale (SSS).

Widespread Pain Index (WPI).

Assessment timepoints: baseline, week 2, week 4, and week 8.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Age between 18 and 65 years

Diagnosis of fibromyalgia according to the 2016 revised ACR criteria

Receiving stable pharmacological and/or non-pharmacological treatment for at least 3 months

Ability to understand study procedures and provide informed consent

Exclusion criteria

Pregnancy

History of epilepsy or cardiac arrhythmia

Acute or chronic infection

Heart failure (NYHA class II-IV)

Renal failure stage II or higher

Active malignancy

Psychotic disorders or current psychiatric treatment

Diagnosis of immune-mediated rheumatic disease

Treatment and study plan

Active Transcutaneous Auricular Vagus Nerve Stimulation (taVNS)

Device

Active TaVNS delivered with the VagusStim® device (Vagus Medical Technologies, Istanbul, Türkiye). The bipolar electrode was placed on the left cymba concha. Stimulation was applied for 30 minutes per day, 5 days per week, for 4 weeks (20 sessions). Parameters included frequency 1-30 Hz, pulse width 50-250 μs, and current intensity individually adjusted (0.1-36 mA) to the participant's sensory threshold.

Sham transcutaneous auricular vagus nerve stimulation

Device

Sham stimulation delivered with the same VagusStim® device under identical conditions. The electrode was rotated and placed on the left earlobe, which lacks vagal innervation. Sessions lasted 30 minutes per day, 5 days per week, for 4 weeks (20 sessions). No effective vagus nerve stimulation was delivered, preserving participant blinding.

Primary outcomes

  1. Fibromyalgia Impact Questionnaire (FIQ)

    Time frame: Baseline, Week 2, Week 4, Week 8

    The FIQ evaluates the overall health status and functional impact of fibromyalgia, including physical functioning, pain, fatigue, and mood. Scores range from 0 to 100, with higher scores reflecting greater disease impact.

  2. Pittsburgh Sleep Quality Index (PSQI)

    Time frame: Baseline, Week 2, Week 4, Week 8

    The PSQI is a validated self-report questionnaire that assesses subjective sleep quality and disturbances over the past month. Scores range from 0 to 21, with higher scores indicating poorer sleep quality.

  3. Central Sensitization Inventory (CSI)

    Time frame: Baseline, Week 2, Week 4, Week 8

    The CSI is a 25-item self-report questionnaire assessing symptoms related to central sensitization, including sensitivity to pain, fatigue, and cognitive complaints. Scores range from 0 to 100, with higher scores indicating greater sensitization.

Secondary outcomes

  1. Tampa Scale for Kinesiophobia (TSK)

    Time frame: Baseline, Week 2, Week 4, Week 8

    The TSK is a 17-item self-report questionnaire measuring fear of movement or reinjury. Items are scored on a 4-point Likert scale, with total scores ranging from 17 to 68. Higher scores indicate greater kinesiophobia.

  2. Visual Analog Scale (VAS) for Pain

    Time frame: Baseline, Week 2, Week 4, Week 8

    Pain intensity is assessed using a 10-cm visual analog scale, with 0 representing "no pain" and 10 representing "worst imaginable pain." Participants mark their pain level along the line, which is recorded as a numeric score.

Sponsors and collaborators

Lead sponsor

Hatice Betigul Meral

Other

Registry information

Official study title

Effects of Transcutaneous Auricular Vagus Nerve Stimulation on Symptom Severity, Sleep Quality, Central Sensitization, and Kinesiophobia in Fibromyalgia: A Randomized Controlled Trial

Important dates

Study start
2025
Primary completion
2025
Study completion
2025
First posted
Sep 15, 2025
Registry last updated
Jan 15, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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