I had decompression surgery for a condition called syringomyelia. The cyst inside my spinal cord extended over three levels. The MRI shows no change in the size of the cyst. But I feel much better. How do you explain this?
Syringomyelia is a general term that refers to a spinal cord disorder. A tube-shaped cavity (cyst) forms within the spinal cord. The cyst is also called a syrinx. Syrinx comes from a Greek word that means hollow reed. The word syringe also comes from this word.

The syrinx can expand and elongate down several levels in the spine. In the process, the spinal cord can be damaged or even destroyed. This damage may result in pain, weakness, and stiffness in the back, shoulders, arms, or legs. Some patients report headaches or temperature loss in the hands. They can't feel hot or cold sensations.

Shrinkage of the syrinx occurs after surgery in three-fourths of the patients. The remaining quarter (25 per cent) experience a change in symptoms but no change in syrinx size.

Experts suspect that location of the syrinx, not its size, is the key factor. This may explain why you got relief from your symptoms without a change in the degree of syrinx size.