--as neuropathy, and central nervous system conditions such as MS, can affect autonomic systems in the body, from the temperature regulation systems, to blood pressure control, to digestion and elimination.

The autonomic functioning of the body is controlled primarily through small, lighly- or un-myelinated fibers, and, in fact, many people with predominantly small-fiber syndromes report problems with sweating, temeperature, digestion, elimination, blood pressure upon rising, and the like (though often the degree of disruption is mild or sublclinical). And many of the tests for small-fiber diagnosis, such as the Sudomotor axon reflex test or the other sweat tests such as Billye has described, and the Valsalva tilt-table tests, look for disruption in those autonomic functions.

Problem, of course, is that so many of the meds we take, and many of the supplements we use, can have effects on the elimination pathways independent of what our nerves may be doing (or not doing). Opiates are notoriously constipating. Magnesium formulations, and many anticonvulsants, are "stimulating". It may be hard to pull out the effects of these from those of dysfunctional nerves, but I wouldn't be surprised if those with small-fiber or mixed syndromes report these effects from time to time (they're common among diabetic neuropathic patients, for example).

And then, there are the effects one may have if one has celiac disease, or Crohn's, or hypertriglyceridemia, just to think of a few conditions that have primary gastric effects and may secondarily cause neuropathy, either through autoimmune or malabsorptive mechansims . . .it's very difficult to tease out.