Syringomyelia is a condition in which a cyst, called a syrinx, forms within the spinal cord. This cyst expands and elongates over time, destroying the center of the spinal cord which can result in pain, weakness, stiffness in the back, shoulders, arms, or legs, headaches, and insensitivity to temperature (especially in the hands).
https://rarediseases.info.nih.gov/diseases/7725/syringomyelia

