In addition to the direct symptoms of RSD/CRPS, which can include swelling, skin changes, movement disorders, temperature changes and very severe pain in the affected body part, complications in other parts of the body are also very common.

Cognitive abilities can be impacted in patients suffering from chronic pain conditions such as RSD and CRPS. A study of several hundred CRPS patients in which neuropsychological tests for memory and executive brain function were administered found that about two-thirds had at least mild deficits with working memory and visual memory and executive functions. Functional MRI studies of patients with RSD in an injured hand found that changes in the brain associated with “re-wiring” to accommodate the RSD symptoms may have been interfering with certain cognitive functions.

Among CRPS patients with more than one affected limb, nearly all were experiencing chronic weakness or fatigue, which may be associated with natural inflammatory responses within the body’s immune system to injury and pain. These long-term responses may be also be associated with a variety of negative consequences beyond just chronic tiredness.

A study of more than 2000 CRPS sufferers with long-term duration of their condition (more than two years) found a number of increased cardiac abnormalities, including a pulse rate that was higher than typical, fainting — or a feeling of fainting — in about 10% of the patients, and common complaints of atypical chest pain (although most of the patients studied did not themselves relate their chest pain symptoms to their CRPS conditions). It has been suggested that these symptoms of atypical chest pain may be connected in many of the patients to injury or inflammation of the intercostal nerve, because in about two-thirds of the cases the atypical chest pain could be replicated by simply raising the patient’s arm, which would stretch these nerves.

A review of nearly 300 individuals with moderate or severe CRPS discovered that about 1 in 6 reported shortness of breath. For some of the people suffering the symptoms, this appeared to be related to increased pain with full inspiration, which would irritate the same intercostal nerves discussed above in relation to atypical chest pain. Other possible causes included general physical de-conditioning due to long-standing pain and disability from CRPS.

Normally, when the body detects a fall in blood pressure, the autonomic nervous system will automatically try to compensate by increasing the heart rate. Studies have found that in some long-term CRPS patients, this autonomic reflex may be suppressed, and it has been suggested that this may be related to the other autonomic nervous system components of RSD/CRPS that include temperature changes in the effected limb and changes in sweating. (These changes can also result in misdiagnosis of RSD/CRPS as conditions such as vascular insufficiency or fibromyalgia, which are also associated with these skins changes in the limbs.)

Neurogenic edema (swelling) is a very common complication seen with CRPS/RSD. In people who have had RSD for more than a year, three-quarters experience this swelling, and this proportion increases to about 90% of those who have the condition long-term. The swelling is also often accompanied by redness and temperature change, and these symptoms are thought to be related to several chemicals released by the body as part of the inflammatory response usually mounted to deal with injury or infection. These chemicals also enhance function of the pain receptors in the area.

Nearly all RSD and CRPS patients have significant negative impacts upon their musculoskeletal systems. Some 70% of sufferers report weakness, and may experience actual atrophy of muscles that aren’t being used as they would be normally due to the pain of RSD/CRPS. A variety of degenerative processes have been found in the muscles of patients with the most severe types of RSD/CRPS, including fatty degeneration in the muscle tissue, lack of oxygen in the tissue, and dysfunction in the mitochondria that provide energy at the cellular level. Most CRPS patients also report bone and joint pain. X-rays and MRI studies have shown bone tissues changes in RSD/CRPS patients include demineralization of the bone and bone marrow edema. Later fractures are very common in patients with CRPS-I (RSD). There is evidence showing that bone health is highly dependent upon small nerve fiber innervation, and RSD patients lacking this proper nerve function suffer both higher rates of bone fracture and poor fracture healing.

As would logically be expected, CRPS patients report significantly increased stress levels due to both the pain from their symptoms, and the interference in their daily lives, work and relationships. In a study of some 300 patients about 70% reported severe tiredness and/or fatigue. Some of this may be related to the cardiac, neuropsychological, and immune system problems described above or to the narcotic medications many must take to relieve their pain symptoms. However, in some CRPS patients, changes may be taking place in the endocrine system including the ways in which the hypothalamus, pituitary, and adrenal glands jointly respond to pain signals. Separately, it appears that about one in three patients with moderate to severe symptoms of CRPS also experience hypothrydoidism.

The largest organ in our bodies is the skin, and skin color changes are reported by about 70% of CRPS patients, increasing to more than 80% for long-term sufferers. Depending upon the stage and severity of the condition, this could include redness, blue color, and/or mottling. About three-quarters of patients would experience swelling in the first years, increasing to about 90% of patients in the long-term. Approximately 20% of patients reported rashes or odd skin lesions. Some of these changes in skin condition are believed to be related to muscle atrophy and capillary thickening in the underlying tissues. Studies of skin tissue in RSD patients have also shown reductions in the skin sweat glands and small nerve fibers, with an increase in the size and number of capillaries — this is more common with those patients with severe, long-term symptoms. About one-third of CRPS patients will experience changes in sweating, with about 75% of them having increased sweating and 25% having decreased sweating. Spontaneous bruising is also common, even in areas away from the site of original injury — it is thought that the same inflammatory response producing neurogenic edema in these patients may also be responsible for the bruising.

Changes in the gastrointestinal system are common in CRPS patients, including constipation, nausea, vomiting, swallowing difficulty, and indigestion. One study found about 1 in 6 patients having been diagnosed with irritable bowel syndrome the the beginning of their CRPS condition. Some of these instances may be related to the physical limitations of the CRPS condition and to the pain medications that the patients may be taking for symptom control, but it seems clear that there are other connections between CRPS and the these gastrointenstinal problems — for patients with CRPS for more than 5 years, fully 90% report severe constipation, diarrhea and/or symptoms of irritable bowel.

CRPS/RSD is by itself a very complicated condition that medicine is only beginning to understand. It is very clear from multiple medical studies and patient reviews, however, that in addition to the specific body parts and limbs that are directly impacted by CRPS/RSD, there are also widespread impacts on body organs and systems far removed from the site of injury.