Postural Orthostatic Tachycardia Syndrome, Fibromyalgia, RSD and CRPS all share a common feature of an abnormally behaving autonomic nervous system. In that regard all of these conditions can be classified as a form of Dysautonomia. With dysautonomias the autonomic portion of the nervous system (that part that controls body functions such as skin temperature, sweating, pupil dilatation, heart rate, breathing and other independent functions) does not function just right. Depending on how much the system is not working right a whole host of symptoms can arise. Learn more about conditions related to dysautonomia on piedmontpmr.com.