title: Predictors of pain relieving response to sympathetic blockade in complex regional pain syndrome type 1.
abstract: BACKGROUND
  Sympathetic blockade with local anesthetics is used frequently in the management of complex regional pain syndrome type 1(CRPS-1), with variable degrees of success in pain relief. The current study investigated which signs or symptoms of CRPS-1 could be predictive of outcome. The incidence of side effects and complications of sympathetic blockade also were determined prospectively.
  
  
  METHODS
  A prospective observational study was done of 49 patients with CRPS-1 in one extremity only and for less than 1-yr duration who had severe pain and persistent functional impairment with no response to standard treatment with medication and physical therapy.
  
  
  RESULTS
  Fifteen (31%) patients had good or moderate response. The response rate was not different in patient groups with cold or warm type CRPS-1 or in those with more or less than 1.5°C differential increase in skin temperature after sympathetic blockade. Allodynia and hypoesthesia were negative predictors for treatment success in CRPS-1. There were no symptoms or signs of CRPS-1 that positively predicted treatment success. A majority of patients (84%) experienced transient side effects such as headache, dysphagia, increased pain, backache, nausea, blurred vision, groin pain, hoarseness, and hematoma at the puncture site. No major complications were reported.
  
  
  CONCLUSIONS
  The presence of allodynia and hypoesthesia are negative predictors for treatment success. The selection of sympathetic blockade as treatment for CRPS-1 should be balanced carefully between potential success and side effect ratio. The procedure is as likely to cause a transient increase in pain as a decrease in pain. Patients should be informed accordingly.
authors.affiliation: Department of Anesthesiology and Pain Management, St. Elisabeth Hospital, Tilburg, The Netherlands. f.v.eys@elisabeth.nl
authors.forename: Frank
authors.initials: F
authors.lastname: van Eijs
authors.forename: José
authors.initials: J
authors.lastname: Geurts
authors.forename: Maarten
authors.initials: M
authors.lastname: van Kleef
authors.forename: Catharina G
authors.initials: CG
authors.lastname: Faber
authors.forename: Roberto S
authors.initials: RS
authors.lastname: Perez
authors.forename: Alfons G H
authors.initials: AG
authors.lastname: Kessels
authors.forename: Jan
authors.initials: J
authors.lastname: Van Zundert
mesh_terms: D000328:Adult; D001340:Autonomic Nerve Block; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000188:drug therapy / Q000209:etiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D059408:Pain Management; D010147:Pain Measurement / Q000187:drug effects; D010641:Phenotype; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012019:Reflex Sympathetic Dystrophy / Q000188:drug therapy*; D012044:Regression Analysis; D012881:Skin Temperature / Q000187:drug effects; D013233:Stellate Ganglion / Q000187:drug effects; D016896:Treatment Outcome