Two answers. Left to conventional treatments, the chance of remission in an adult after the first year is almost zero. That said, there are a few newer therapies out there that are looking pretty good. Hence the need for a really smart pain specialist.

First, as to the bad news, check out The Natural History of Complex Regional Pain Syndrome, Schwartzman RJ, Erwin KL, Alexander GM, Clin J Pain 2009;25:273-280 FREE FULL TEXT @ http://www.rsds.org/2/library/articl...lexanderGM.pdf

Abstract
OBJECTIVE: Complex regional pain syndrome (CRPS) is a severe chronic pain condition characterized by sensory, autonomic, motor, and dystrophic signs and symptoms. This study was undertaken to expand our current knowledge of the evolution of CRPS signs and symptoms with duration of disease. METHOD: This was a retrospective, cross-sectional analysis using data extracted from a patient questionnaire to evaluate the clinical characteristics of CRPS at different time points of disease progression. Data from the questionnaire included pain characteristics and associated symptoms. It also included autonomic, motor, and dystrophic symptoms and also initiating events, ameliorating and aggravating factors, quality of life, work status, comorbid conditions, pattern of pain spread, family history, and demographics. Comparisons were made of different parameters as they varied with disease duration. RESULTS: A total of 656 patients with CRPS of at least 1-year duration were evaluated. The average age of all participants was 37.5 years, with disease duration varying from 1 to 46 years. The majority of participants were white (96%). A total of 80.3% were females. None of the patients in this study demonstrated spontaneous remission of their symptoms. The pain in these patients was refractory showing only modest improvement with most current therapies. DISCUSSION: This study shows that although CRPS is a progressive disease, after 1 year, the majority of the signs and symptoms were well developed and although many variables worsen over the course of the illness, the majority demonstrated only moderate increases with disease duration.

PMID: 19590474 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov/pubmed/19590474

But as noted, there are several promising therapies. Again, and following up on what Sandy said, the one that's gotten the most press is the use of the "dissociative" general anesthetic ketamine, a powerful NDMA receptor-antagonist. Ketamine has been delivered in a number of forms: orally (to little effect), through 5-day continuous inpatient infusions, either at "subanesthestic" or coma inducing level, or through a series of out-patient infusions. Perhaps the best overview of the state of the science can be found in comparing Outpatient intravenous ketamine for the treatment of complex regional pain syndrome: A double-blind placebo controlled study, Schwartzman RJ, Alexander GM, Grothusen JR, Paylor T, Reichenberger E, Perreault M, Pain 2009 Dec 15;147(1-3):107-15. Epub 2009 Sep 23 FREE FULL TEXT @ http://www.rsds.org/2/library/articl...n_Pain2009.pdf, with a commentary published in response, Intravenous ketamine for CRPS: Making too much of too little? Bell RF, Moore RA, Pain 2010 March 25 FREE FULL TEXT @ http://www.rsds.org/2/library/articl...amine_2010.pdf

The abstract to the article by Schwartzman et al is as follows:

Abstract
Complex regional pain syndrome (CRPS) is a severe chronic pain condition that most often develops following trauma. The pathophysiology of CRPS is not known but both clinical and experimental evidence demonstrate the important of the NMDA receptor and glial activation in its induction and maintenance. Ketamine is the most potent clinically available safe NMDA antagonist that has a well established role in the treatment of acute and chronic pain. This randomized double-blind placebo controlled trial was designed to evaluate the effectiveness of intravenous ketamine in the treatment of CRPS. Before treatment, after informed consent was obtained, each subject was randomized into a ketamine or a placebo infusion group. Study subjects were evaluated for at least 2 weeks prior to treatment and for 3 months following treatment. All subjects were infused intravenously with normal saline with or without ketamine for 4h (25ml/h) daily for 10 days. The maximum ketamine infusion rate was 0.35mg/kg/h, not to exceed 25mg/h over a 4h period. Subjects in both the ketamine and placebo groups were administered clonidine and versed. This study showed that intravenous ketamine administered in an outpatient setting resulted in statistically significant (p<0.05) reductions in many pain parameters. It also showed that subjects in our placebo group demonstrated no treatment effect in any parameter. The results of this study warrant a larger randomized placebo controlled trial using higher doses of ketamine and a longer follow-up period.

PMID: 19783371 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov/pubmed/19783371

And while there is no abstract to the rebuttal commentary, it's only a couple of pages long and reads well enough, basically taking the position that the studies in support of ketamine are inconclusive due to small sample size or other methodological impediments. In balancing the two points of view, it bears noting that (1) because CRPS is still something of an "orphan illness" there is little if any NIH money available for larger studies and where ketamine itself has been generic for many years, there is no pharmaceutical company with an interest in bankrolling it either, and (2) the authors of the commentary are from the U.K., where the technique is absolutely disfavored by the NHS. As for the experience in this country, there are many people on this forum who swear by it and in fact major health insurance companies are beginning to pay for it.

For what it's worth, I was originally signed up to be in two of Dr. Schwartzman's ketamine trials in 2004, a sub-anesthetic 5-day infusion program in Philadelphia, which was suspended 3 weeks before I was supposed to go there, for further negotiations with the hospital's IRB (the Institutional Review Board which oversees human studies), and when that came to a temporary halt, I suddenly found myself with tickets in hand, ready to go to Germany for the coma trial, when, 9 days before I was set to leave, I was waived off by the German doctors due to pre-existing (and pre-disclosed) glaucoma, a per se disqualifying condition for the coma treatment, as well as any clinical trial. (As I understand it, even at a low dose, I would have to have my pressures monitored by an opthamology resident every 4 hours.)

There are other treatments of promise, particularly in the early stage of the disease, in which sympathetic blocks are administered, but - along with the local anesthetic - Botox or Remicaide (Infliximab) are administered as well. See, Successful Intravenous Regional Block with Low-Dose Tumor Necrosis Factor-[Alpha] Antibody Infliximab for Treatment of Complex Regional Pain Syndrome 1, Bernateck M, Rolke R, Birklein F, Treede RD, Fink M, Karst M, Int Anesth Res Soc 2007;105(4):1148-1151 FREE FULL TEXT @ http://www.rsds.org/2/library/articl...teck_Rolke.pdf and, Sympathetic block with botulinum toxin to treat complex regional pain syndrome, Carroll I, Clark JD, Mackey S, Ann Neurol. 2009 Mar;65(3):348-51 FREE FULL TEXT @ http://www.ncbi.nlm.nih.gov/pmc/arti...ihms140157.pdf

There is however one therapy, but not a cure, that has made a huge difference for a lot of people including myself, which consists of periodic infusions of so-called "biphosphonates," first developed to prevent the uptake of bone into the blood of multiple myeloma patients. See, e.g., 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 FREE FULL TEXT @ http://www.rsds.org/2/library/articl..._Finlayson.pdf The drug I use, Zometa (zoledronic acid) has the advantage over older forms in that it can be infused in only 15 minutes, as opposed to 4 hours; however, serious complications can result if taken by people needing significant dental work, e.g., root canals, or with any pre-existing loss of renal (kidney) function.

Other promising therapies, stopping however well short of cures, can be found on the RSDSA Research and Clinical Articles page under the heading Treatments http://www.rsds.org/2/library/articl...html#Treatment and include intravenous magnesium as well as i.v. immunoglobulin (IVIG).

Finally, there remains my personal favorite among potential cures, electroconvulsive therapy (ECT) using only the newer and significantly safer version, "'right' or 'non-dominant' unilateral" ECT (RUL ECT), as opposed to the traditional "bilateral" approach where electrodes were placed on both temples: BL ECT. See, Treatment of CRPS with ECT,Wolanin MW, Gulevski V, Schwartzman R, Pain Phys. 2007;10:573-578 (noting complete remission 4 years after a woman with chronic CRPS-1 received 12 treatments of BL ECT for RSD related depression) FREE FULL TEXT @ http://www.rsds.org/2/library/articl...chwartzman.pdf and, Right Unilateral Electroconvulsive Therapy Treatment for CRPS, Michaels F Jr., Pract Pain Manage. 2008 March;68-75 (noting misreading in 1994 article by King & Nuss on efficacy of RUL ECT for chronic pain in earlier studies and citing a number of successful case studies involving CRPS) FREE FULL TEXT @ http://www.rsds.org/2/library/articl...haels_CRPS.pdf

Sadly, my pain management doctor was in the process of making arrangements for me to receive 12 applications of RUL ECT on an in-patient basis at his hospital, using not only a high voltage delivered in ultra-short bursts, but with ketamine as a general anesthetic, when we learned that in 1976, in response to the release the year earlier of One Flew Over the Cuckoo's Nest, the voters of California - in their infinite wisdom - outlawed the use of ECT for all but certain defined psychiatric conditions (and only then if approved by multiple doctors as the patient's last best chance) outside of an IRB approved study; and with no hope of securing the funds for such a study, at was game over. So it goes.

I hope some of this is useful.

Mike