Please help me understand what’s happening. I broke my arm in a bicycle accident. It had to be pinned in six places. I wore an external device with pins through the skin to hold it in place. While it was immobilized, I developed something called CRPS. Now I’m in rehab. But all of a sudden, my hand is starting to jerk and tremor. What is that and will it go away with exercise?

Complex regional pain syndrome (CRPS) is triggered by a peripheral event such as a traumatic injury, burn, or bone fracture. The patient develops a wide variety of symptoms affecting sensation and movement.

Sometimes, for reasons still unknown to us, the patient also develops a movement disorder. With CRPS, there’s a loss of motion and loss of function. But with the movement disorder, suddenly they can be jerking motions or tremors of the fingers, hand, or arm.

Some people experience a movement disorder called dystonia. The fingers and wrist start to flex into a fist and won’t open up again. If the leg is affected, the foot does the same thing. The toes point downward and get stuck in a claw-like position.

The natural history (what can or will happen) remains unclear. For some patients, the problem may get worse. It can move up the limb to involve more body parts. Or it can even jump to another limb. If the arm and hand are involved, the shoulder and face can start to develop similar symptoms.

There have been isolated reports of spontaneous recovery. Most of the time, a long course of rehab is needed to maintain motion and function. Whatever triggers the CRPS and movement disorder doesn’t seem to have a means of turning off the changes.

Scientists are working very hard to identify these triggers and mechanisms. The hope is to both prevent the problem from occurring in the first place and treat it once it does occur.