By definition, Carpal Tunnel Syndrome (CTS) occurs when the nerve running through the tunnel at the end of the wrist does not have enough space and is consequently compressed. This results in pain, numbness, tingling, and/or weakness in the palm, side of the thumb, and/or index fingers, which often increases at night. These same symptoms can also be caused if the nerve is compromised higher in the arm, such as in the forearm or even the elbow. Usually, this is due to tight or scar-filled muscle tissue compressing the nerve as it passes through the arm.