People with complex regional pain syndrome (CRPS), a syndrome that causes pain usually after an injury to an arm or a leg, may also develop dystonia, or muscle spasms or twitches. More and more, researchers are finding that some patients with CRPS are developing these movement disorders (MDs).
Up to now, the number of patients affected with MDs after CRPS varies according to the study being discussed. In one study of 1,006 patients, 5 percent were reported to have some sort of MD. In another study of 145 patients, 30 percent of the patients were noted to have MDs.
There isn’t a lot of detail available for this patient group. It has been found, however, that dystonia with CRPS usually happens in the hand and causes the wrist and thumb to curl in, called flexion. In the leg, it starts in the foot, sometimes causing the toes to “claw.” Researchers also noticed that patients with CRPS and dystonia tend to be younger than patients with CRPS without dystonia, and the more extremities affected, the more can be affected. Dystonia can come on gradually or it can come on suddenly. It also usually begins on the same side as the injury before the CRPS.
There isn’t a connection between when the injury happened and when CRPS and the dystonia begins, so sometimes it is hard to tell what follows what. As well, it isn’t known if bracing or immobilizing an arm or a leg after injury makes it more likely for dystonia to develop. Researchers have also looked into the psychological aspect of CRPS and CRPS-related dystonia, but that, too, hasn’t found anything.
All the research results in there being no clear understanding of what causes some patients with CRPS to develop dystonia and not others. Because of this, no clear treatments have evolved. Medications don’t seem to help and while psychosocial interventions may help some patients, they don’t help all. Physiotherapy, tried with some patients, could make the situation worse, rather than better.
The author concludes that both CRPS and dystonia can be triggered together, but that they are two different illnesses. Studies of co-existing disorders like these two may “lead to new insights into the processes underlying each of them, and to fresh approaches to treatment.”