Hello Pamela and welcome to this forum. I am sorry you have had this diagnosis for little Isabelle. The advice you have been given is excellent and I cannot add to this.
Except, to reinforce the advice concerning the diuretic. When my dog Molly was first diagnosed, the original specialist did not prescribe the diuretic and predicted Molly would probably not survive for more than a few months. This was because she had a very large pre-syrinx on her spine (fluid ). Fortunately I went to see a neurologist who put her on diuretics immediately. Her next scan showed this had vanished completely. This was approximately 18 months ago.
It is devastating when you first find out. With the right medication and management Isabelle will probably stabilise.
I have put a website together to help people understand this disease in jargon free language. www.cavaliermatters.org
Please let us know how you and Isabelle are coping.
Tania and The Three Cavaliers!
Dotty!- A Sweet Little Tri
Molly - Pretty Tri Dougall - Gorgeous Blenheim