There can never be a guaranteed 100% resolution of your symptoms, but surgery is often indicated when all other treatment options have failed.
There is a Chiari forum on MedHelp and all of the members of that community are dealing with the symptoms and treatment options specific to this condition.
You might get further information and support from others who have had the specific surgery you are contemplating.
Just go to the home page and scroll down to the C column and you will see the Chiari Malformation forum. I think you will be able to obtain a great deal of information from them that we might not be able to provide.
Best wishes ----