These diseases are considered rare: AAI/GME/Chiari/Syringomyelia. They all have similar symptoms, for the most part, but the treatment is different for each. It is extremely urgent that you go to a board certified neurologist and get the apropriate tests done (MRI, Spinal tap and others) to get the correct diagnosis and treatment for your dog. (For example:If GME: the treatment is to give very high doses of the meds, lower doses aren't effective, important to know exactly what you pup has so the apropriate meds are given).
Much of the info about these disorders on the web may be old, and these diseases did not have good prognoses not too long ago. More recently, and with more recent, frequent diagnoses, vet medicine has made advances in treating and successfully managing these previously thought of as terminal diseases.
This is the neurologist that specializes in the treatment of GME. If you can't go there, I would recommend emailing him, or calling him. He, or his assistants, will be able to tell you more about the testing that needs to be done, and may be able to recommend a B.C. Neuro Vet in your area that can work with him in evaluating your pup and getting him on the appropriate path to healing.
Allen Sisson, D.V.M., M.S.,
Diplomate ACVIM Neurology/Neurosurgery
Angell Animal Medical Center
350 South Huntington Avenue
Jamaica Plain, MA 02130
Tel: (617) 522-7282 (press 4, then 2 when the automated operator message begins or 6 to speak to someone)
Fax: (617) 989-1648
asisson@mspca.org