Reflex Sympathetic Dystrophy Definition and "Pathophysiology" (how the condition comes about)

Reflex sympathetic dystrophy is a condition which causes severe pain - far out of proportion to the underlying mechanical condition.

RSD and related conditions fall into the category of "nerve pain" though no specific nerve around the knee need be injured for the conditions to be present. RSD and its related conditions have gone by many names since the original denomination of causalgia by Mitchell in 1862. These names include Sudeck's atrophy, shoulder-hand syndrome, and most recently CRPS [complex regional pain syndrome].

"Reflex" reflects the thinking that the condition is an involuntary neurological response to a stimulus.

"Sympathetic" refers to the sympathetic nervous system, and "dystrophy" is what can eventually happen to the involved joint or limb (thinning and dysfunction).

Contrary to pregnancy it is not an "either you have it or you don’t" situation. It is rather like a flu virus the symptoms of which can vary significantly from case to case.

It remains common teaching that there is an emotional predisposition to reflex sympathetic dystrophy. Anxious, depressed, laconic, flat-affect women are the poster children for this condition, but RSD can occur in anyone.

Etiology (where it comes from)

RSD requires an inciting agent - usually, but not necessarily, trauma. Interestingly, the trauma need not be severe, and in fact is usually relatively mild. A simple wrist sprain, for example, can trigger RSD. Surgery is a form of trauma, and, not surprisingly, a source of RSD. Although long, complex operations can cause RSD, short, outpatient procedures can also be the cause. This is consistent with the concept that the inciting trauma is usually minimal. At this point, it appears that patient predisposition is the major factor with respect to the development of reflex sympathetic dystrophy.

Signs and Symptoms

In classic RSD, pain is abnormally severe. The patient early on feels a constant, burning pain, the affected joint is stiff, the skin is warm (decreased sympathetic activity!) and mottled. Light touch is extremely painful (allodynia). In the more chronic, dystrophic stages, the skin is cool and shiny. Eventually the joint develops contractures and becomes atrophic. However, not all of these signs and symptoms will be present in all cases, and the symptoms will vary over time.

Recovery can take months or years especially if the condition is severe and the diagnosis is made long after the onset of the condition. Because RSD can be very subtle in its presentation, and because there is no simple, risk-free, reliable test it is not uncommon to first detect RSD once it is in its chronic stage.

At the physical therapy level, there is a fine line between too much and just enough. The joint must be mobilized - but not too aggressively. Cold in the early phase can be soothing, but extreme cold may be harmful. Gentle massage can be pleasant, but deep friction massage may aggravate the condition.

In a chicken-and-egg situation, a mechanical problem can contribute to a continuation of RSD. Surgery may then need to be performed in the presence of known RSD. This would seem to be contraindicated since surgery (as well as any trauma) can exacerbate RSD. Fortunately, if the patient is known to have reflex sympathetic dystrophy, epidural medications administered during a surgical procedure can successfully address the problem.

RSD-like Conditions

To make life even more difficult, there are, I believe, pain conditions which are not RSD: they do not necessarily involve the sympathetic nerves nor will they respond to a sympathetic block. Nevertheless, the patient feels a constant pain not related to a mechanical problem and not caused by localized inflammation of a single nerve as one might see with a neuroma. There is still much research to be done in this area.

I refer you to www.spineuniverse.com/treatment/pain/ag_060500richeiner_neuropain.html for a deeper review of the subject.