Dear DETPAS -
Sadly, cognitive changes go with the territory of RSD/CRPS. Roughly 2/3 of CRPS patients will exhibit a loss in "executive functioning," attentional, planning, and/or organizational skills, while of that group, a third of them will have memory issues of one sort or another, leading to a diagnosis of something referred to as "global cognitive impairment," NOT to be confused with dementia.
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. Epub 2010 Mar 19. And significantly, those results were INDEPENDENT of any medication patients happened to be on.
In addition, the portion of the cortex that directly receives signal input from the thalamus, the "Anterior Insula" (AI) - the health of which is associated with ease of emotional regulation - has been shown to be significantly impacted for the worse in CRPS patients, with a marked loss in cortical thickness.
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;60:570-581.
The good news is that a number of studies have shown that the "cortical reorganization" of CRPS is apparently reversible with treatment. To that end, although the observation was made in a different patient population entirely, the use of tDCS has even been associated with the recovery of proper nouns.
Improved proper name recall in aging after electrical stimulation of the anterior temporal lobes, Ross LA, McCoy D, Coslett HB, Olson IR, Wolk DA,
Front Aging Neurosci. 2011;3:16. Epub 2011 Oct 12.
And for what it's worth, I'm unaware of any cognitive issues associated with lumbar sympathectomies. Typically, the problem was that they just stopped working after a couple of years. That, and people have reported secondary pain of the sort you experienced, on account of which they are essentially no longer performed today.
I hope this is useful.
Mike