"A promising new experimental brain procedure. Known as a thalamotomy, this procedure destroys the part of the thalamus involved in movement control. In 1996, Fox underwent the operation, and it helped relieve the worst of the tremors."
Some of the reading I did about this said that the medication itself, if it's l-dopa or a form of it that he is taking, can cause the same symptoms after a great length of time on it.
Don't know if that's what he's on, but it is what my grandmother took for her Parkinson's, 15+ years ago.
That was eight to ten years ago and this is now. Parkinson's is a degenerative disease. There is no cure.