I don't know of any direct link between DDAVP and autonomic dysfunction and central pain - are you sure there is no other cause. DDAVP is made to replace a naturally occurring substance, which could over time suppress any remaining ability to produce it by the body theoretically.
Ask your doctors what scientific evidence (ie from the medical literature) they have to support their diagnosis
Good luck
I just wanted to ask what made your doctors think that you have central pain syndrome. May I also ask what autonomic symptoms are you experiencing? I would appreciate you explaining this to me as there is someone else I know who has complained of same thing.