Defining the therapeutic role of local anesthetic sympathetic blockade in complex regional pain syndrome: a narrative and systematic review.
OBJECTIVE
There is growing controversy on the value of blocking the sympathetic nervous system for the treatment of complex regional pain syndromes (CRPS). The authors sought to evaluate the efficacy of sympathetic blockade with local anesthetic in these syndromes. In addition, they performed a comprehensive review of the pathophysiology and other treatments for CRPS.


METHODS
Systematic review of the literature was performed. MEDLINE was searched from 1966 through 1999. The authors identified only three randomized controlled trials (RCTs) that evaluated sympathetic blockade with local anesthetic, but because of differences in study design they were unable to pool the study data. The authors therefore included nonrandomized studies and case series.


METHODS
Studies were included if local anesthetic sympathetic blockade was used in at least 10 patients. Studies were excluded if continuous infusion techniques, somatic nerve blocks, or combined sympatholytic therapies were evaluated.


METHODS
Pain relief was classified as full, partial, or absent. The lack of a comparison group in the studies allowed only the calculation of distribution of the response categories, and the sum of the pooled rates does not equal 100%.


RESULTS
Twenty-nine studies were included that evaluated 1,144 patients. Nineteen studies were retrospective, 5 prospective case series, 3 RCTs, and 2 nonrandomized controlled studies. The quality of the publications was generally poor. Twenty-nine percent of patients had full response, 41% had partial response, and 32% had absent response. It was not possible to estimate the duration of pain relief.


CONCLUSIONS
This review raises questions as to the efficacy of local anesthetic sympathetic blockade as treatment of CRPS. Its efficacy is based mainly on case series. Less than one third of patients obtained full pain relief. The absence of control groups in case series leads to an overestimation of the treatment response that can explain the findings.
Cepeda
M Soledad
MS
Department of Anesthesia, San Ignacio Hospital, and Javeriana University School of Medicine, Bogota, Colombia.
Lau
Joseph
J
Carr
Daniel B
DB
D020918:Complex Regional Pain Syndromes / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology*; D003937:Diagnosis, Differential; D006801:Humans; D016239:MEDLINE; D023421:Models, Animal; D010147:Pain Measurement / Q000379:methods / Q000706:statistics & numerical data*; D017410:Practice Guidelines as Topic / Q000592:standards*; D011584:Psychology; D012955:Societies, Medical; D013564:Sympathetic Nervous System / Q000187:drug effects*; D013565:Sympatholytics / Q000627:therapeutic use*; D016896:Treatment Outcome
D013565:Sympatholytics