Dear Eileen -

I too had the privilege of being wired and infused in Hahnemann Hospital in Philadelphia, back in 2004, only mine was for a preliminary 5-day infusion of lidocaine, which didn't work. I did however have the pleasure of having the catheters running out of a "central line" in the open wall of my chest, where the CRPS had so compromised my peripheral vascular functions that they couldn't get a 20 gauge needle into my arms and the hospital was perhaps months away from going to the now standard "PICC lines." I was then set for a low dose ketamine infusion when the program was temporarily put on hold, and when it was resumed, it was with a whole new set of eligibility requirements, and I was off the list for what was then an experimental trial.

Dr. Robert J. Schwartzman, who runs the program in Philadelphia through the Drexel University College of Medicine, has since suggested, in a report of a very small "pilot study," that 10 day "sub-anesthetic" ketamine infusions appear to be ineffective altogether, in "in long-standing CRPS patients who have been refractory to all standard modes of therapy." That is, 4 women received infusions for 10 days each, and none of them experience any pain relief, and "objective findings" based upon skin condition were similarly unchanged. "A Pilot Open-Label Study of the Efficacy of Subanesthetic Isomeric S(+)-Ketamine in Refractory CRPS Patients," Ralph-Thomas Kiefer, MD, Peter Rohr, MD, Annette Ploppa, MD, Boris Nohé, MD, Hans-Jürgen Dieterich, MD, John Grothusen, PhD, Karl-Heinz Altemeyer, MD, Klaus Unertl, MD, and Robert J. Schwartzman, MD, Pain Medicine, Vol. 9, No. 1, 2008, which available for free download on the RSDSA Medical Achieves webpage, below. The article further notes that the "best results of ketamine therapy to date have been demonstrated in early and well-localized CRPS."

What is really interesting about the article is how, in the "Discussion" section, the authors embrace those published reports that found ketamine to be effective in cases where patients had CRPS for 8 months or less. This included the most famous study [that of Dr. Graeme Correll and others, "Subanesthetic Ketamine Infusion Therapy: A Retrospective Analysis of a Novel Therapeutic Approach to Complex Regional Pain Syndrome," Pain Medicine, Vol., 5, No. 3, 2004, also on RSDSA webpage] that had great results using a doses substantially below that which was administered to chronic CRPS patients in the study on which the the 2008 article was based. (Perhaps not coincidently, one of the co-authors on the Correll study - Dr. Maleki - worked in Dr. Schwartzman's department at the time the 2004 article was written.) The 2008 article then goes on to briefly consider how CRPS may change when it becomes chronic:

The first hypothesis that other mechanisms than those effected through the NMDAR [N-methyl-D-aspartate receptor, a.k.a. NDMA receptor] may be important on CRPS is supported by failure of a complete translation of the animal data, which supports a crucial role of the NMDAR, in initiation of some neuropathic pain states with clinical experience. Second, the length of time a patient has suffered the disease prior to NMDAR-antagonist intervention may be important for successful NMDAR-antagonist therapy. The dosage of ketamine utilized in this study may have been insufficient to block NMDAR-mediated hyperexcitability of central pain projecting neurons. [Footnotes omitted.]

And FYI in an earlier section of the article, the "NMDAR mechanism" was defined as follows:

A great deal of progress has been achieved in understanding the neurobiology of the syndrome utilizing experimental models but there are differences in these models and the specific aspects of the illness. Recent experimental and clinical studies suggest a major role of the central nervous system in much of the symptomatology seen in CRPS patients. Peripheral and central sensitization of nociceptive [the process of pain transmission, usually relating to a receptive neurone for painful sensations] pathways appears to be a major mechanism. There is solid evidence that the N-methyl-D-aspartate receptor (NMDAR) is involved in central sensitization. [Footnotes omitted.]

But a discussion into what happens as the body shifts to chronic CRPS is way beyond the scope of your question. (To say nothing of my lack of a scientific and/or medical education, as well as that small matter of being far, far removed from an IQ north of 160, where to my knowledge, no one other than Anne Louise Oaklander, MD of Harvard - see below and http://www.neurologynow.com/pt/re/ne...d=1&nav=search - claims to have solved all elements of the CRPS riddle.) However, as to the issue of effective dosing, virtually the same group of authors have been running the "ketamine coma" program for a number of years in Germany, and report, in another article on the RSDSA website, that a study of 20 patients with chronic CRPS that had failed every other treatment showed significantly better results, coupled with (potentially) far greater side-effects. "Efficacy of Ketamine in Anesthetic Dosage for the Treatment of Refractory Complex Regional Pain Syndrome: An Open-Label Phase II Study," Ralph-Thomas Kiefer, MD et al, Pain Medicine, 2008 Nov; 9(8): 1173-201, Epub 2008 Feb 5, also available on the RSDSA webpage.

To find the articles mentioned, just go to the RSDSA Medical Achieves webpage at http://www.rsds.org/2/library/articl...ive/index.html and scroll down to the heading labeled "Ketamine Treatment," where you can open pdf files of a total of 15 articles, which can be freely downloaded.

All that said, I have a good friend with chronic CRPS who gets good, temporary and very expensive relief from four hour ketamine infusions delivered at a decidely "anesthetic" doses, something perhaps along the lines of what Andrea was describing in her post. So to each their own.

Good luck!

Mike

ps For an editorial by a leading researcher questioning whether the central nervous system plays any role in CRPS, see, "RSD/CRPS: the end of the beginning," Oaklander AL, Pain, 2008 Oct 15;139(2):239-40, Epub 2008 Sep 13, also available on the RSDSA webpage under the heading "CRPS Overview." I can also site anyone who's interested to a couple of recent articles that offer fairly convincing evidence that a significant part of chronic CRPS is maintained by the brain itself!