Effects of Repetitive Electric Sensory Stimulation (RSS) as Intervention in Complex-regional-pain-syndrome Type I (CRPS)

Study Overview
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Brief Summary
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The purpose of this study is to test a specific nerve stimulation protocol as therapeutic option in patients diagnosed with CRPS (complex regional pain syndrome) of the upper extremity.

Detailed Description
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A specific high frequency electric stimulation is conveyed at 5 days to the affected hand. Each stimulation session lasts 45 minutes.

Official Title
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Effects of Repetitive Electric Sensory Stimulation on Sensorimotor Performance and Pain Intensity in Complex Regional Pain Syndrome Type I

Conditions
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Complex Regional Pain Syndrome Type I of the Upper Limb

Intervention / Treatment
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* Device: RSS (repetitive sensory stimulation)
* Device: SHAM-RSS


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients diagnosed with CRPS Type I Exclusion Criteria: intolerable hyperalgesia lesions at the fingertips high grade digit contracture central neurologic disorders psychiatric disorders

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Verum-RSS<br>RSS Stimulation with high frequency electric pulses | Device: RSS (repetitive sensory stimulation)<br>* RSS is a high frequency electrical stimulation protocol delivered to the peripheral nerves (median and ulnar nerve) of the hand. The signals are generated by a TENS-stimulator and are conveyed to each finger of the hand via a custom-made hand-shaped device with conductive contacts at each fingertip and at the palmar base. In case of the sham-stimulation no pulses are transmitted.<br>|
| Sham Comparator: Sham-RSS<br>Sham RSS Stimulation (no pulses are transmitted) | Device: SHAM-RSS<br>* The same device as in the RSS intervention is used, but no electrical stimuli are transmitted.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| static tactile 2-point-discrimination threshold | Thresholds on the tip of the index finger of both hands are assessed using the method of constant stimuli. One single needle and seven pairs of needles with different spacings are tested in randomized order. After each presentation, the subject has to report the sensation of one or two needles by answering immediately one or two. Each distance is presented eight times resulting in 64 single decisions. The summed responses are plotted against distance as a psychometric function for absolute threshold and get fitted by a binary logistic regression. Threshold are taken from the fit at the distance at which 50% correct answers are given. | before and after the 5 day stimulation phase with a minimum time of 1h between measurements and start/end of the stimulation (day1 pre and day 5 post) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| pain intensity | Pain intensity is rated by the patient on a 11-point numerical rating scale (NRS). Pain intensity is rated before the start of the 5 day stimulation phase (baseline,pre) and at the end (post, in combination with the other outcome measures). Additionally pain intensity is rated directly before the start of each daily stimulation session and immediately after each session of 45 minute duration. | before and after the 5 day stimulation phase with a minimum time of 1h between measurements and start/end of the stimulation (day1 pre and day 5 post) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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CRPS, repetitive sensory stimulation, cortical reorganization, 2-point-discrimination