title: The predictive value of sympathetic block for the success of spinal cord stimulation.
abstract: OBJECTIVE
  The purpose of this study was to assess the predictive value of response to sympathetic blockade (SB) on the success rate of spinal cord stimulation (SCS) in patients with complex regional pain syndrome.
  
  
  METHODS
  We performed a retrospective study on 23 patients with complex regional pain syndrome who underwent both SB and subsequent SCS trials in the past 3 years at the Massachusetts General Hospital Pain Center, Boston, MA, and Walter Reed Army Medical Center, Washington, DC. Fifteen of these patients underwent permanent placement of an SCS device, and pain relief at 1- and 9-month follow-up was recorded.
  
  
  RESULTS
  Among the 23 patients included in the study, those having transient pain relief with SB were more likely to have a positive SCS trial: all 13 with positive SB had good pain relief during the trial, compared with only 3 of the 10 with negative SB (100% versus 30%, P < 0.001). Among the 10 patients with negative SB, 7 noted poor pain relief during the trial despite adequate coverage, and they did not undergo placement of a permanent device. Among the patients who underwent permanent placement of an SCS device, those who received good pain relief with SB were more likely to have greater than 50% pain relief at 1-month follow-up (100% versus 33%, P = 0.029) and 9-month follow-up (87.5% versus 33.3%, P = 0.15).
  
  
  CONCLUSIONS
  We conclude that patients with good response to SB before SCS are more likely to have a positive response during their SCS trial and long-term pain relief after placement of permanent SCS device.
authors.affiliation: Interventional Pain Program, MGH Pain Center, Departments of Anesthesia and Critical Care and Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA. edhord@partners.org
authors.forename: E Daniela
authors.initials: ED
authors.lastname: Hord
authors.forename: Steven P
authors.initials: SP
authors.lastname: Cohen
authors.forename: G Rees
authors.initials: GR
authors.lastname: Cosgrove
authors.forename: Shihab U
authors.initials: SU
authors.lastname: Ahmed
authors.forename: Ricardo
authors.initials: R
authors.lastname: Vallejo
authors.forename: Yuchiao
authors.initials: Y
authors.lastname: Chang
authors.forename: Milan P
authors.initials: MP
authors.lastname: Stojanovic
mesh_terms: D000328:Adult; D000368:Aged; D001340:Autonomic Nerve Block; D020918:Complex Regional Pain Syndromes / Q000503:physiopathology* / Q000628:therapy*; D004599:Electric Stimulation Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D010147:Pain Measurement; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D013116:Spinal Cord / Q000503:physiopathology*; D013997:Time Factors