Predictors of Analgesic Response to Sympathetic Blockade in Complex Regional Syndrome Type 1

Abstract

Ninewells Hospital and Medical School, Dundee, Scotland. mneil@nhs.netTo the Editor: Van Eijs et al. must be commended for conducting a clinically useful and informative study on the use of sympathetic blockade in the management of complex regional pain syndrome (CRPS) type 1.1Despite many advances in our understanding of the pathophysiology of this condition, CRPS remains a challenging clinical problem. This study informs our practice thanks to a good methodologic process that captures a homogenous group of patients at an early stage of the condition and a thorough assessment of their clinical response to sympathetic blockade.However, despite the merits of the study, I would not be satisfied that what was defined as “standard treatment” was sufficient before undertaking an interventional procedure. Physiotherapy and active mobilization are, of course, fundamental to treatment at all stages of CRPS but should first be supported and made possible by adequate medical therapy. Standard treatment in this study is detailed as comprising 50% dimethyl sulfoxide cream with acetaminophen and tramadol (erroneously termed nonsteroidal antiinflammatory medication in the article) supplemented to aide with physiotherapy. Gabapentin was then added after 3 weeks if analgesia was not satisfactory with this initial combination. Gabapentin is then described as being titrated to a maximum dose of only 1,800 mg/day, with 3 weeks given to assess response. Medical treatment was then considered to have failed if analgesia was insufficient at this point.Although there is no internationally accepted standard of treatment for CRPS, there are a number of therapies that have a good supporting evidence base that should be considered before reverting to an interventional procedure. The use of acetaminophen and tramadol are reasonable first-line choices, but the use of gabapentin as described in this study is inadequate. Gabapentin can be safely titrated to a maximum dose of 3,600 mg and in practice often needs this higher dose for maximum efficacy. In addition, the 3-week limit used in this study probably is too short a time to adequately assess success or failure of gabapentin therapy, which often takes a minimum of 4 weeks to deliver maximum analgesic effect. The protocol used in this study defining standard treatment was, I believe, undertreating with medical therapy in terms of duration and dose of drug administered.Furthermore, a number of other important therapeutic options were not considered as part of initial therapy. The use of oral steroids (e.g. , prednisolone) in early CRPS consistently has been shown to provide a lasting analgesic effect in CRPS,2–5yet as demonstrated in this study, it is seldom used in clinical practice and is not included. In addition, tricyclic antidepressants are widely regarded as being fundamental in both the first- and second-line management of many neuropathic pain problems, including CRPS, either alone or in combination with anticonvulsants. Again, this important component of medical management is not included as part of standard treatment in this study.Medical therapy is not free from side effects; however, because of the potential for significant excess morbidity with a relatively low success rate for sympathetic blockade, far greater emphasis should be given to aggressive medical management of CRPS. The use of short courses of steroids and the combination of tricyclic antidepressants and anticonvulsants for a period of not less than 4 weeks at the maximum tolerated dose should be recommended in addition to physical therapy as standard initial management. I would agree that sympathetic blockade should be reserved for all but the most refractory cases of CRPS but believe that medical therapy must be more comprehensive than that suggested in this article.