Examination of the Pathophysiologic Mechanisms of CRPS by Using QST, CPM, RIC, and Heart Rate Variability QST

Study Overview
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Brief Summary
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This study aims for a better understanding of the pathophysiological mechanisms of the complex regional pain syndrome (CRPS). This will be done by testing the quantitative sensory testing, the remote ischemic conditioning, the conditioned pain modulation (CPM) and the analysis of the heart-rate variability in patients with CRPS and a control-group. We hypothesize decreased conditioned pain modulation, less effects of remote ischemic conditioning and an affection of the heart-rate variability in patients with CPRS.

Detailed Description
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CRPS is an illness which (seriously) affects patients in their daily life activity. The fact that the pathophysiological mechanisms are not well understood yet makes it hard to treat these patients in the right manner. Possible patho-mechanisms might be microvascular changes and dysfunctions of the inhibitory descending pain system. Furthermore, recent studies showed that CRPS patients have macrovascular changes and a lower blood level of NO on the affected side. This indicates a NO mediated perfusion dysfunction. Aim of this study is to examine the pathophysiological mechanism of CRPS in relation to healthy subjects and patients with a different type of pain syndrome (carpal tunnel syndrome) on the upper limb. The investigators try to get a better understanding of the changes in the pain inhibitory system and micro- and macrocirculating blood-systems, as well as of the autonomic system of CRPS-patients.

Official Title
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Examination of the Pathological Mechanism of the Complex Regional Pain Syndrome of the Upper Limb in Comparison to Patients With Painful Carpal Tunnel Syndrome and Healthy Subjects - an Explorative Clinical Study

Conditions
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Complex Regional Pain Syndrome, Carpal Tunnel Syndrome, Neuralgia

Participation Criteria
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Eligibility Criteria
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CRPS-patients Inclusion Criteria: Unilateral pain on the upper limbs, based on a scintigraphic ensured CRPS (average pain in the last 4 weeks ≥ 3 in pain Detect) Pain history < 1 year Exclusion criteria: Bilateral pain on the upper limbs Inadequate knowledge of the german language in speaking and writing Acute psychiatric sickness Polyneuropathy Any added neuropathic sickness on the not affected upper limb sight Intolerable pain during the testing Injuries within the tested areal Acute injuries on the hand Pregnancy Missing informed consent CTS-patients Inclusion Criteria: Unilateral pain on the upper limbs, based on a scintigraphic ensured CRPS (average pain in the last 4 weeks ≥ 3 in pain Detect) Pain history < 1 year Exclusion criteria: Bilateral pain on the upper limbs Inadequate knowledge of the german language in speaking and writing Acute psychiatric sickness Polyneuropathy Any added neuropathic sickness on the not affected upper limb sight Intolerable pain during the testing Injuries within the tested areal Acute injuries on the hand Pregnancy Missing informed consent Healthy subjects Inclusion Criteria: Age > 18 years Written consent Exclusion criteria: Inadequate knowledge of the german language in speaking and writing Current pain Pain within in the last 14 days Any serious internistic medicin Any chronic skin disease Any central neural sickness Polyneuropathy Peripheral nerve lesion within the testing areal Any radiculopathy with permanent pain (in the last 3 months) Any psychiatric sickness Migraine ( at least one attack in the last 24 h) Repeating headache (in the last 3 month on >5 days/month) Taking any analgesics in the last 14 days Taking triptans in the last 24 months Taking any psychotropic's in the last 3 months Any repeated taking of medication, including amber or different psychostimulants (excluding contraceptives) Taking of any prescription and non-prescription drugs (except contraceptives) in the last 7 days or 5 half-life periods(which is always longer) before including into the study Achilles reflex absent or within in the side-difference pathologic hypoactive or hyperactive pallaesthesia <5/8 (<4/8 at >60 years) on the internal malleolus on both sides abuse of alcohol or medications/drugs (corresponding to the DSM IV criteria) joining a medical study <30 days before inclusion into the current study jet lag, irregular work schedule, sleep deprivation within the last 3 days change of intestity during physical activity, e.g. beginning an activity in the last weeks before inclusion into the current study

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| 30 healthy probands<br>group without the condition of interest | |
| 30 CRPS patients<br>group with condition of interest | |
| 30 CTS patients<br>group with a different type of pain on the upper limbs | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| CPM effect | Conditioned Pain Modulation measured by the Heat-Cold-Pain Method | 60 seconds | 
| Remote Ischemic Conditioning | the perfusion increasing effect after RIC in all groups | 45 minutes |