Syringomyelia (sih-ring-go-my-E-lee-uh) is the development of a fluid-filled cyst (syrinx) within your spinal cord. Over time, the cyst can enlarge, damaging your spinal cord and causing pain, weakness and stiffness, among other symptoms.
https://www.mayoclinic.org/diseases-conditions/syringomyelia/symptoms-causes/syc-20354771

