Test in a private location. Use a scribe for tests, if needed. Use a reader for tests, if needed. Note that this is for the kind of situation where eye or head tics prevent the student from reading. Scheduling considerations in academic programming.
Tics tend to worsen as the day wears on, so schedule the most demanding classes for the morning.
The mental energy spent suppressing tics may fatigue the student. If a student's tics impose on others, problem solve collaboratively with the student what they can do to be considerate and protective of their peers and teachers. Well, this is your chance, because your student needs you to model acceptance. For really intense waxing cycles, the student may feel more comfortable if you allow them to go find an empty room to work in. If tics are creating problems with peers, allow the older student to leave class a few minutes early to avoid hallway crowds and situations in which they will be under more stimulation and stress.