Changing Views about Complex Regional Pain Syndrome

» Changing Views about Complex Regional Pain Syndrome
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Scientists in The Netherlands have added a new piece to the mystery of treating complex regional pain syndrome (CRPS). CRPS is a very painful disorder that affects people after a seemingly minor injury sometimes. The problem is not understood very well. Doctors don't know what causes it or why it happens. That makes CRPS a difficult condition to treat effectively.

In recent years, anti-inflammatory medications have been used with mixed results. But the fact that this approach works for some patients makes it worth investigating further. If CRPS is an exaggerated response of the immune system to tissue injury, then inflammatory messengers and inflammatory cells must be part of the signaling system that bring on the painful symptoms.

People with complex regional pain syndrome (CRPS) often experience intense pain, swelling and skin changes (color, texture, hair growth, temperature). The net result is a loss of motion and function along with reduced quality of life.

Scientists hope that by cutting off immune cells like cytokines, chemokines, and mast cells, it might be possible to stop (or even prevent) these disabling symptoms. How successful have anti-inflammatories been so far? That's the topic of this review article.

The authors searched all publication databases looking for any information on results of treatment for complex regional pain syndrome (CRPS) using medications. They were specifically interested in outcomes with the use of anti-inflammatory drugs.

A total of 24 articles were found that were of good enough study quality to be included. The two types of medications used in these studies were corticosteroids and free radical scavengers. Corticosteroids included oral prednisolone and piroxicam (CNT). Free radical scavengers included DMSO, vitamin C, and Mannitol.

Free radicals are unstable oxygen atoms that form when they lose an electron. Electrons like to be in pairs. The loss of one electron literally puts the atom into orbit. It becomes a scavenger looking for another oxygen atom so that it can rob or steal the necessary electron.

The result is a cascade of damage to the cells as new radicals are formed in order to salvage the damaged oxygen atoms. Compounds like DMSO, vitamin C, and Mannitol work by getting rid of free radicals. Inflammatory reactions are reduced by eliminating free radicals. The end-result is to limit the amount of tissue damage that occurs from inflammation. In some studies, corticosteroids and free radical scavengers were used together.

For anyone who wants to take a closer look, the authors created a table with study characteristics for all 24 studies. Items of interest for comparison included references cited, diagnostic term used for patients, study design, intervention (drug treatment used), outcome measures, and results. Some of the ways results were measured included joint range of motion, pain, change in sensory symptoms, and improvements in daily activity level.

Here's a quick summary of what they found. Both classes of drugs (corticosteroids and free radical scavengers) worked. Patients receiving either medication showed significant improvements. This tells us that it is possible to stop the inflammatory process in different ways (turning off inflammatory cells, getting rid of damaging free radicals).

But there's a big "But" in their findings. There were just as many patients who didn't get better as those who did improve. Naturally, the scientists wondered "Why"? (Or more appropriately, "Why not"?) There are several possibilities.

First, let's go back to the symptoms. Not all patients with complex regional pain syndrome (CRPS) have the exact same symptoms. There is some belief that perhaps the differences have to do with different pathologic and physiologic mechanisms for the CRPS from one patient to another.

Second, the medications were not all in the same formulation. Some were topical (applied to the skin) while others were oral (taken by mouth). Some studies used intravenous (IV) directly into the blood stream, which is a faster method of drug delivery when compared with topical or oral dosing.

If nothing else, the results of this review study confirmed there is a role for anti-inflammatories in the treatment of complex regional pain syndrome (CRPS). But much more study is needed to figure out what works best (single drugs or combinations), in what form (topical, oral, intravenous), at what dosage, and for which patients.

Ideally, finding a way to prevent this painful condition would be the best goal. Some researchers will continue to study treatment comparisons. Others will continue to look for the key to unlock the mysteries behind the mechanisms of complex regional pain syndrome (CRPS). One way or the other, the goal is to find a better way to manage this chronic pain problem.

Reference: Sigrid G. L. Fischer, et al. Anti-Inflammatory Treatment of Complex Regional Pain Syndrome. In Pain. November 2010. Vol. 151. No. 2. Pp. 251-256.

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