<qa>  What is the name of the medication that may influence the central nervous system?Patients taking medication that may influence the central nervous system, such as phenytoin, phenobarbital, carbamazepine, clonazepam, and antidepressants but not limited to these for their paroxysmal dyskinesias not seizures will be asked to hold the medication prior to the study. A sufficient drug washout period will be established dependant upon the individual drug. Subjects may be admitted to the NIH if necessary. They will be asked to abstain from alcohol and caffeine 24 hours prior to the study as well. 