Hi
One thing we have tried, which I believe has helped, has been to greatly reduce my son's exposure to salicylates, which are naturally occurring chemicals found in fruits and vegetables. There is alot of info on the net about it, but essentially he only eats pears, golden delicious apples, and sometimes bananas and mangoes. As for vegetables, he eats potatoes, and iceberg lettuce, with small amounts of others thrown in sometimes. It seems difficult at first, but we have gotten used to it. It can take a while for the body to rid itself of salicylates, approx 6 weeks I have read. This, together with the removal of artifical additives in his diet, has, I believe, really helped our son's tics to be 90% improved. Worth a try, at any rate!
All the best,
Karen