I've had numerous tests for carpal tunnel syndrome to find the cause of my cold and numb hands. The latest tests were normal for blood flow but abnormal for vibration. What does this tell me?

Studies of adults with carpal tunnel syndrome (CTS) and another disorder called upper limb pain disorder (ULPD) have shown some surprising results. Blood flow and blood volume appear to be normal for these two groups. And changes in vibration threshold are present on both sides even when symptoms only occur in one arm or hand.

An increased vibration threshold was found in all patients with CTS or ULPD. Increased vibratory threshold means that when compared to normal, healthy adults, it took a higher amount of vibration before the patient could feel a sense of vibration.

Scientists think these results suggest that a change in the central processing of pain is occurring. They propose that anyone with chronic pain would experience the same changes. Increased vibratory threshold is not linked with local pressure on the nerves to the arm, wrist, or hand. It is a more of a global or central nervous system problem.

It's not clear yet how this information will change treatment. The focus must shift from local treatment of the painful areas to finding ways to affect global processing in the central nervous system.