If the syrinx is small in diameter then some Dr.'s will say it can not be causing pain but through researching myself I have found there are many people that have them that do have pain so don't be afraid to get a second or third opinion. I have a 2mm diameter syrinx in my spinal cord from t3-t10 and only one neurosurgeon has said it is causing my severe pain. The websites given by the good Dr. are very informative.
A syrinx is a tube-like cavity within the spinal cord that is an abnormal enlargement of a very very tiny cavity we all have called the central canal. The need for surgical intervention depends on where it is within the spine, how wide and long it is, and whether it is the cause of the patient's symptoms. Syrinxes are an incidental finding in a small percentage of the population, meaning it's there in normal people and doesn't cause any problems. If your wife does in fact have a significant syrinx that is causing her symptoms, then they may need to do a mesh (patch-like) repair that may or may not be extensive, again depending on location and size. I would recommend a neurosurgeon who is a spine specialist. If you are nearby, Dr. Ed Benzel is a fantastic, world renowned expert in the field. Good luck.
For more info contact:
American Syringomyelia Alliance project
www.asap4sm.com
Beth Israel Med Ctr: syringomyelia
http://nyneurosurgery.org/syrinx/syringomyelia.htm
National Institute of Neuorolgical disorders and stroke
http://www.ninds.nih.gov/health_and_medical/disorders/syringomyelia_short.htm