F.D. is a neurological disorder or condition which affects the fine movements and prevents an instrumental musician from practicing and playing – anytime, constantly, because suddenly he completely loses the control over the fingers (i.e. one or more fingers) of one hand. (In classical guitar, it is virtually always the right hand.)
The fact that countless professional and non-professional musicians suffer from this devastating handicap and that almost all of the professionals are not able to resume their performing (giving concerts) in any way shows that it is an extremely complex matter. Different therapies have been offered, for decades, but an actual and full rehabilitation within a reasonable period of time (e.g. one or two years) can be achieved only rarely, by very few patients.
In most cases, focal dystonia is the final result or consequence of different circumstances and factors which occur together unnoticed and over a long period of time. The musician cannot realize he is developing it, because the hands, all the fingers – still – manage to do what he asks, demands from them. There are no alarm signals, because the damage does not happen in the hand / in the fingers. FD is not something you can feel physically.
When the musician realizes the loss of control of the finger(s) it is too late. He has become (or he has turned himself into) a dystonic musician and he can never again play in the same way he used to. Nevertheless, he may play again, depending on the extent and the will, the ability to undergo a long, persevering therapy.
99% of the teachers either have no clue about FD and its causes, or what they know is way too little to protect themselves and their pupils against it. (FD is not a subject taught thoroughly at the music schools of universities.) This is why many of them develop FD and their students are not “prepared” to protect themselves.
FD is absolutely the worst thing that can happen to any instrumental musician, because if he has developed it, suddenly he just cannot play anymore, or he can play in a very limited and hampered way, not in the least the way he used to play before. In about 90% of cases this means the end of a performing career.