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Complex Regional Pain Syndrome May Lead to Movement Disorders in Some Patients

Patients with complex regional pain syndrome (CRPS) may also experience movement disorders, such as tremors and seizure-like movements in the arms and/or legs. These movement disorders (MDs) seem to be more common than originally thought, with as many as 9 percent to 49 percent of patients with CRPS developing them.

Up to now, researchers haven't known very much about the onset of MDs, how to determine if they will happen to a particular patient, and how it spreads in the body. Because it is important to understand the onset of MDs and the time frame after onset of CRPS, researchers in this study describe the characteristics of MDs in patients with CRPS, and factors that might affect the onset and outcome of MDs.

The researchers studied 185 patients with CRPS, the majority of whom were female (86.5 percent). Ninety six patients had more than one limb affected by the CRPS. For the most part, the patients had been treated with medications such as relaxants, antidepressants, antiseizure medications, and pain killers. None were effective in treating the MDs, or they were stopped because of the side effects they were causing. Most of the MDs were tight, flexed postures of the wrists or ankles, although in some patients, the MDs also affected the elbows, shoulders, knees, and/or hips. The majority of patients (89.1 percent) had dystonia, or muscle spasms and twitches, so the researchers compared patients with dystonia and patients without.

The patients with dystonia had CRPS longer than those who did not have dystonia (7.4 years compared with 4 years), and had CRPS in more than one limb. Patients with dystonia were also an average of 10 years younger than patients without.

Although the timing of MDs after onset of CRPS isn't known, in this study, 56 percent of the patients developed MDs more than 1 month after developing CRPS. Researchers have many theories as to what causes the MDs, but nothing has been proven yet. What they have found is that once a patient has dystonia in one part of the body, there is a higher risk of developing it elsewhere.

The authors conclude that, although the mechanisms aren't yet known, there does seem to be a connection to the brain's ability to recover from an injury at the neuron, or brain cell, level after it has been damaged from CRPS.

References: Monique A. van Rijn et al. Onset and progression of dystonia in Complex Regional Pain Syndrome. In Pain. July 2007. Vol. 130. Pp. 287-293.

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