Hello there. Looking at the FDA approved prescribing information sheet for Savella, it's hard to tell it apart from Cymbalta. http://www.frx.com/pi/Savella_pi.pdf they are both Serotonin–norepinephrine reuptake inhibitors (SNRIs), for which there is a decent Wikipedia article @ http://en.wikipedia.org/wiki/Seroton...take_inhibitor

In particular, in the prescribing insert page, check out Paragraph 5.4 and the warning that SNRIs can increase heart rate and patients heart rates should be check before they go on the drug and periodically thereafter. Based on mt experience 10 years ago at UCLA, where an adult ADHD clinic put me on a related SSRI end the first time abyine checked my heart tate was when I presented in the ER with tachycardia (that went away as soon as the med was out of my system) I would guess that these warnings are there to protect the manfacturer, knowing full-well that too few doctors will follow it in practice.

I have tried SNRIs as well, but they just make my spasms worse. Perhaps other people find them useful. I would just note that while Savella has been approved for fibromyalgia, amd the supporting studies are referenced in Paragraph 14 of the Savella's prescribing information sheet - and set in a particular pdf format that makes it impossible to copy - there is apparently at least some suggestion in the literature that these studies may not be generalizable to other brain conditions. See, Serotonin-norepinephrine reuptake inhibitors for pain control: premise and promise, Marks DM, Shah MJ, Patkar AA, Masand PS, Park GY, Pae CU, Curr Neuropharmacol. 2009 Dec;7(4):331-6.

Department of Psychiatry and Behavioral Science, Duke University Medical Center, Durham, NC, USA.

Abstract
The precise mechanisms of pain perception and transmission in the central nervous system have not been fully elucidated. However, extensive data support a role for the monoamine neurotransmitters, serotonin and norepinephrine, in the modulation of pain. Experiments with animal models of pain indicate that noradrenergic interventions, and to a lesser extent serotonergic interventions, reduce pain-related behavior. This is supported by data from clinical trials in humans in which antidepressants have been shown to reduce pain and functional impairment in central and neuropathic pain conditions. These effects are particularly well-studied in trials with serotonin-norepinephrine reuptake inhibitors (SNRIs), which have provided a useful tool in the clinician's arsenal, particularly considering the limitations of other classes of pain medications such as opioids, anti-inflammatories, and anticonvulsants (i.e., limited efficacy, safety and tolerability issues). Moreover, painful physical symptoms are frequently comorbid with major psychiatric disorders such as major depressive disorder and anxiety disorders. This paper reviewed and summarized the rationale and potential role of SNRIs for the control of pain including clinical and preclinical background. Currently evidence does not definitely support a role of the SNRIs, while limited data propose a putative promise of SNRIs in the treatment of pain related disorders including fibromyalgia and depressed patients with multiple somatic complaints. More researches are warranted to generalize currently available preliminary evidences.

PMID: 20514212 [PubMed - in process]PMCID: PMC2811866

http://www.ncbi.nlm.nih.gov/pubmed/20514212

I will post if I can get a copy of the article.

Then too, even if Savella is 30% effective on fibrimyalgia pain, and assuming that carries over to CRPS, I am not aware of any claim that Savella - or any other SNRI - modifies the loss of executive function found in Fibromyalgia, which, along with selective memory issues is part and parcel of CRPS:

Fibromyalgia is a pain syndrome that is thought to be related to CRPS. Recent functional imaging research with patients suffering from fibromyalgia reveals an altered network of neural structures involving dorsolateral and orbitomedial frontal areas, the anterior cingulate, and, in some studies, the parahippocampal gyrus (Burgmer et al., 2009; Kuchinad et al., 2007 ; Schmidt-Wilcke et al., 2007). Luerding, Weigand, Bogdahn, and Schmidt-Wilcke (2008)also studied a group of patients with fi bromyalgia by using MRI voxel-based morphometry (VMB) and found an association between poor performance on the digits backwards test and a decrease in frontal lobe activity. Derailed or altered functioning in a network of anatomic structures, as described above, would be consistent with the executive, naming, and episodic memory defi cits seen in the current research.

Neuropsychological deficits associated with Complex Regional Pain Syndrome, Libon DJ, Schwartzman RJ, Eppig J, et al, J Int Neuropsychol Soc. 2010 May;16(3):566-73, E-pub 2010 Mar 19 at *6, FREE FULL TEXT @ http://www.rsds.org/2/library/articl...ychol_2010.pdf

Quite frankly, as far as "brain fog" is concerned, I frankly don't see any applicability of SNRIs where it's not simply a matter of chemical imbalances in the brain, but actual "cortical reorganization" as well as a loss of certain cotical gray tissue. See, The Brain in Chronic CRPS Pain: Abnormal Gray-White Matter Interactions in Emotional and Autonomic Regions, Geha PY, Baliki MN, Harden RN, Bauer WR, Parrish TB, Apkarian AV, Neuron. 2008;60:570-581FREE FULL TEXT @ http://www.rsds.org/2/library/articl...aliki_etal.pdf AND Libon et al (2010) (above).

Hope I'm wrong.

Mike