It looks like you have a diagnosis. A syringomyelia is a fluid-filled cyst (syrinx) within the spinal cord.
Mayo clinic - Syringomyelia...
"Syringomyelia symptoms usually develop slowly over time. If your syringomyelia is caused by protrusion of brain tissue into your spinal canal (Chiari malformation), symptoms generally may begin between ages 25 and 40.
In some cases, coughing or straining may trigger symptoms of syringomyelia, although neither causes syringomyelia.
The following early signs and symptoms of syringomyelia may affect the back of your neck, shoulders, arms and hands first:
Muscle weakness and wasting (atrophy)
Loss of reflexes
Loss of sensitivity to pain and temperature
Other signs and symptoms of syringomyelia may include:
Stiffness in your back, shoulders, arms and legs
Pain in your neck, arms and back
Bowel and bladder function problems
Muscle weakness and spasms in your legs
Spinal curvature (scoliosis)"