Complex Regional Pain Syndrome Type I
Conditions
Brief summary
This randomized, participant- and assessor-blinded, sham-controlled study will evaluate the effectiveness of transcutaneous auricular vagus nerve stimulation (taVNS) added to standard rehabilitation in adults with complex regional pain syndrome type I (CRPS-I) affecting the hand or upper extremity. A total of 20 participants will be randomly assigned to two parallel groups. Both groups will receive the same standard rehabilitation program 5 days per week for 4 weeks. In addition, the experimental group will receive active taVNS, while the control group will receive sham taVNS for 30 minutes per session over the same 4-week period. The primary outcome is change in pain intensity measured using the Numerical Rating Scale. Secondary outcomes include CRPS clinical severity, hand and wrist circumference, hand function and activities of daily living, health-related quality of life, anxiety and depression symptoms, and perceived stress. Assessments will be performed at baseline, at the end of treatment at week 4, and during follow-up at weeks 8 and 12.
Detailed description
Complex regional pain syndrome type I is a disabling condition that may develop after trauma, fracture, surgery, or immobilization. It is characterized by pain that is disproportionate to the initial injury and may be accompanied by sensory, autonomic, motor, edema, and trophic abnormalities. Despite multidisciplinary rehabilitation and pharmacological treatment, some patients continue to experience persistent pain and functional impairment. Transcutaneous auricular vagus nerve stimulation is a non-invasive neuromodulation method that stimulates auricular regions innervated by the vagus nerve. It may affect pain processing, autonomic nervous system regulation, central sensitization, and neuroinflammatory mechanisms that may contribute to CRPS-I. Evidence regarding the clinical effectiveness of taVNS in this patient population remains limited. The primary objective of this study is to determine whether active taVNS added to standard rehabilitation provides greater pain reduction than sham taVNS added to the same rehabilitation program. Secondary objectives are to compare the effects of the interventions on CRPS clinical severity, edema-related hand and wrist circumference measurements, hand function, activities of daily living, health-related quality of life, anxiety and depression symptoms, and perceived stress. Participants will be randomly allocated in a 1:1 ratio to standard rehabilitation plus active taVNS or standard rehabilitation plus sham taVNS. Both groups will receive an identical 4-week rehabilitation program. Active and sham stimulation will be delivered with the same session duration and frequency. Participants and the outcomes assessor will be blinded to group allocation. The physiotherapist administering the stimulation will be aware of the allocation and will not participate in outcome assessments. Treatment effects and their persistence will be evaluated at weeks 4, 8, and 12.
Interventions
Active transcutaneous auricular vagus nerve stimulation will be applied to the auricular concha region for 30 minutes per session, 5 days per week for 4 weeks, for a total of 20 sessions. Stimulation intensity will be individually adjusted to produce a tolerable paresthesia without pain. The intervention will be administered by a trained physiotherapist in addition to the standard rehabilitation program.
Sham transcutaneous auricular vagus nerve stimulation will be administered using the same device, session duration, and treatment schedule as active taVNS: 30 minutes per session, 5 days per week for 4 weeks, for a total of 20 sessions. The electrode placement and/or stimulation parameters will be configured according to a prespecified sham protocol intended not to produce therapeutic vagal stimulation. The sham intervention will be administered by a trained physiotherapist in addition to the standard rehabilitation program.
All participants will receive the standard physical therapy and rehabilitation program routinely used in our clinic for patients with CRPS-I and based on current literature. The program will include contrast baths, transcutaneous electrical nerve stimulation, desensitization techniques, passive and active range-of-motion exercises, isometric and isotonic strengthening exercises, progressive loading exercises, hand dexterity and coordination activities, and functional training focused on activities of daily living. The rehabilitation program will be administered 5 days per week for 4 weeks.
Sponsors
Liv Hospital Vadistanbul
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Outcomes Assessor)
Masking description
Participants and the outcomes assessor will be blinded to group allocation. The physiotherapist administering active or sham transcutaneous auricular vagus nerve stimulation will be aware of the assigned intervention and will not participate in outcome assessments. Participants in both groups will receive stimulation with the same session duration and frequency
Intervention model description
Participants will be randomly assigned in a 1:1 ratio to two parallel groups: standard rehabilitation plus active transcutaneous auricular vagus nerve stimulation or standard rehabilitation plus sham transcutaneous auricular vagus nerve stimulation. Participants will remain in their assigned groups throughout the study, with no crossover between groups.
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
No
Inclusion criteria
* Diagnosis of complex regional pain syndrome type I according to the Budapest diagnostic criteria * Age 18 to 65 years * CRPS type I affecting the hand following a traumatic cause, including surgery, fracture, and/or immobilization of the hand or upper extremity * Willingness to participate in the study and provision of written informed consent
Exclusion criteria
* Diagnosis of complex regional pain syndrome type II * CRPS type I developing after stroke * Acute or post-acute rehabilitation following hand tendon repair * Presence of a comorbid condition that may substantially affect functional status or health-related quality of life, including decompensated heart failure, chronic kidney failure, or malignancy * Arthritis affecting the hand * Acute arterial or venous thrombosis of the upper extremity * History of arterial or venous injury of the upper extremity
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Pain Intensity Assessed With the Numerical Rating Scale | Baseline and weeks 4, 8, and 12 | Pain intensity will be assessed using an 11-point Numerical Rating Scale ranging from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate greater pain intensity. Change from baseline will be evaluated at weeks 4, 8, and 12. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in Complex Regional Pain Syndrome Severity Assessed With the CRPS Severity Score | Baseline and weeks 4, 8, and 12 | Clinical severity of complex regional pain syndrome will be assessed using the CRPS Severity Score, which evaluates CRPS-related symptoms and clinical signs. The total score ranges from 0 to 16, with higher scores indicating greater disease severity. Change from baseline will be evaluated at weeks 4, 8, and 12. |
| Change in Hand Circumference | Baseline and weeks 4, 8, and 12 | Hand circumference of the affected extremity will be measured in centimeters at a standardized anatomical reference point using a measuring tape. Three consecutive measurements will be obtained at each assessment, and the mean value will be recorded. Higher values indicate greater hand circumference. Change from baseline will be evaluated at weeks 4, 8, and 12. |
| Change in Wrist Circumference | Baseline and weeks 4, 8, and 12 | Wrist circumference of the affected extremity will be measured in centimeters at a standardized anatomical reference point using a measuring tape. Three consecutive measurements will be obtained at each assessment, and the mean value will be recorded. Higher values indicate greater wrist circumference. Change from baseline will be evaluated at weeks 4, 8, and 12. |
| Change in Hand Function Assessed With the Duruöz Hand Index | Baseline and weeks 4, 8, and 12 | Hand function and difficulty performing daily manual activities will be assessed using the 18-item Duruöz Hand Index. Each item is scored from 0 to 5, producing a total score ranging from 0 to 90. Higher scores indicate greater hand-related functional disability. Change from baseline will be evaluated at weeks 4, 8, and 12. |
Contacts
CONTACTMuhsin Doran, MD
CONTACTmuhsin doran, MD
PRINCIPAL_INVESTIGATORMuhsin Doran
Liv Hospital Vadistanbul
Outcome results
None listed