Mechanism and Treatment of Sympathetically Maintained Pain
40 CRPS patients will be recruited over a three-year period (target of 160 patients at all sites). Assessment of exclusion criteria will be undertaken during initial recruitment. Exclusion criteria are: <18 years; a second chronic pain syndrome that would interfere with pain rating; psychiatric comorbidity; pain in both hands or feet; pregnancy or breastfeeding; sympathectomy in the affected limb; use of topical medication; known sensitivity to alpha 1- adrenoceptor agonists or other contraindications. Patients will maintain their regular oral medications throughout the study period.
Assessment of sympathetically maintained pain (SMP) will require an intradermal dose of Phenylephrine to rekindle SMP and mechanical hyperalgesia. Clonidine will be used to control for affects of lgometer iction and may inhibit SMP by inhibiting the release of more norepinephrine from sympathetic nerve terminals. Skin biopsies will be obtained under sterile conditions from a site of mechanical or thermal hyperalgesia using a 3mm diameter skin biopsy punch under local anesthesia. Samples from a mirror image site on the contralateral body side will also be taken.
|Complex Regional Pain Syndrome (CRPS)||Drug: phenylephrine and clonidine Other: punch biopsy|
|Study Design:||Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Supportive Care
- expressed pain in patients with sensitivity following nerve trauma [ Time Frame: Day 1 ]Determine whether this neural expression is altered in the skin of a subgroup of patients whose pain is associated with increased adrenergic sensitivity after nerve trauma.
- expression of pain association with chronic inflammation in patients with sympathetically maintained pain [ Time Frame: Day 1 ]Determine whether heightened expression of cutaneous 1-adrenoceptors is associated with signs of chronic inflammation in patients with sympathetically maintained pain
- decrease in pain after topical adrenoceptor blockade. [ Time Frame: 2 weeks after blockade ]To determine whether pain decreases in this subgroup after topical 1-adrenoceptor blockade.
|Study Start Date:||August 2012|
|Study Completion Date:||December 2016|
|Primary Completion Date:||June 2016 (Final data collection date for primary outcome measure)|
Experimental: phenylephrine and clonidine
Subjects will be injected with phenylephrine and clonidine at affected and unaffected sites.
Drug: phenylephrine and clonidine
Subjects will be injected with phenylephrine and clonidine at both affected and unaffected sites.Other: punch biopsy
Other Name: After local anesthetic, subjects will receive punch biopsy (1/8"diameter and 1/8" deep) from both affected and unaffected sites.
Please refer to this study by its ClinicalTrials.gov identifier: NCT01813149
|United States, Ohio|
|Cleveland, Ohio, United States, 44195|