Scientists continue to unravel the mystery of complex regional pain syndrome (CRPS). CRPS is a condition that develops after surgery or some other type of trauma. The patient develops exquisite pain and/or tenderness usually of one extremity (arm or leg). Symptoms of sweating, hair growth, swelling, and changes in skin color and temperature develop in that extremity. Changes in the nail growth and strength are also common symptoms of CRPS.
No one knows exactly what causes CRPS to develop — or why only certain people (usually women) are affected. There appears to be involvement of both the immune system and nervous system. A recent study using a drug called baclofen may shed some light on this condition.
Baclofen is a drug that has been used to reduce spasticity by stopping the messages that go from the muscles to the spine. They do this by inhibiting the GABA receptors in the nervous system. The result is to prevent the release of neurotransmitters. Neurotransmitters are chemicals that send and receive signals between a neuron (nerve cell) and the rest of the body.
The fact that the baclofen really helped patients who had CRPS and dystonia was proof that the nervous system (and especially GABA inhibition) is part of the underlying pathology. Dystonia is the abnormal movement of a body part. The patient experiences involuntary (not under their control) muscle contractions. The arm or leg twists, freezes into one position, or twitches repetitively.
But other studies have also shown that something goes wrong in the local immune system of the skin and/or there is inflammation of the sensory nerves. The result is a mixed up set of messages to and from the spinal cord.
Although women tend to be affected more than men, there is no convincing evidence that it’s an inherited genetic trait. More study is needed before the condition is fully understood. Like many neurologic-immune based problems, it is likely multifactorial. This means there are many variables that contribute to the development of CRPS.