Syringomyelia (SM) is a disorder in which a cyst forms within the spinal cord. This cyst, called a syrinx, expands and elongates over time, destroying the center of the cord. Since the spinal cord connects the brain to the nerves in the extremities, this damage may result in pain, weakness, and stiffness in the back, shoulders, arms or legs. Other symptoms may include headaches and loss of the ability to feel extremes of hot or cold, especially in the hands and disruption in body temperature. SM may also adversely affect sweating, sexual function and bladder and bowel control.