Likely so. However, in contrast to the two-year cut-off point provided to jimbo by his neurologist, the study by Ackerman and Zhang found that 25 patients receiving stellate ganglion blocks for (upper body) CRPS broke out into three groups: those who had complete, partial and no relief whatsoever, and of those 25 who had either complete or partial relief, the longest duration between the onset of symptoms and the beginning of treatment with blocks was ONLY 13.5 weeks: or just a little over 3 months. [But see below.]

But that doesn't foreclose other avenues. Has anyone raised the use of biphosphonates with you? They are not appropriate for everyone - in particular people who need significant dental work - but one major review of treatments found them the to be the ONLY treatment that met the authors, standards for effective CRPS treatment in a literature review completed in 2009, which for sn unknown reason, did not consider ketamine one way or another. See, Treatment of complex regional pain syndrome: a review of the evidence [Traitement du syndrome de douleur re´gionale complexe: une revue des donne´es probantes], Tran DQH, Duong S, Bertini P, Finlayson RJ, Can J Anesth. 2010;57:149 - 166, at 151 - 156, FULL ONLINE TEXT @ http://www.rsds.org/pdfsall/Tran_Duo..._Finlayson.pdf:

Abstract
PURPOSE: This narrative review summarizes the evidence derived from randomized controlled trials pertaining to the treatment of complex regional pain syndrome (CRPS).

SOURCE: Using the MEDLINE (January 1950 to April 2009) and EMBASE (January 1980 to April 2009) databases, the following medical subject headings (MeSH) were searched: "Complex Regional Pain Syndrome", "Reflex Sympathetic Dystrophy", and "causalgia" as well as the key words "algodystrophy", "Sudeck's atrophy", "shoulder hand syndrome", "neurodystrophy", "neuroalgodystrophy", "reflex neuromuscular dystrophy", and "posttraumatic dystrophy". Results were limited to randomized controlled trials (RCTs) conducted on human subjects, written in English, published in peer-reviewed journals, and pertinent to treatment.

PRINCIPAL FINDINGS: The search criteria yielded 41 RCTs with a mean of 31.7 subjects per study. Blinded assessment and sample size justification were provided in 70.7% and 19.5% of RCTs, respectively. Only biphosphonates appear to offer clear benefits for patients with CRPS. Improvement has been reported with dimethyl sulfoxide, steroids, epidural clonidine, intrathecal baclofen, spinal cord stimulation, and motor imagery programs, but further trials are required. The available evidence does not support the use of calcitonin, vasodilators, or sympatholytic and neuromodulative intravenous regional blockade. Clear benefits have not been reported with stellate/lumbar sympathetic blocks, mannitol, gabapentin, and physical/occupational therapy.

CONCLUSIONS: Published RCTs can only provide limited evidence to formulate recommendations for treatment of CRPS. In this review, no study was excluded based on factors such as sample size justification, statistical power, blinding, definition of intervention allocation, or clinical outcomes. Thus, evidence derived from "weaker" trials may be overemphasized. Further well-designed RCTs are warranted. [Emphasis added.]

PMID: 20054678 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov/pubmed/20054678

Having said this, there has been a fair amount of discussion of biphosphonates on this forum through the years. I would encourage you to use the "Search" function at the top of NT pages, looking for threads with "biphosphonates" in the title.

Mike


PS As both Lit Love and Dubious note, and I acknowledge in the following response to Dubious, while this may apply in the majority of cases (and the blocks in fact stopped working for me after a few months) there are exceptions to every rule, this one included. Specifically, all bets are off where there is ongoing neuro-inflammation, typically where there has been spread to a previously unaffected limb withing the last few months, and apparently in some clear cases of CRPS Type II as well.