<qa>  What is one of the main problems in the study of musicians dystonias?Clinical rating scales, even those that have been validated, do not detect subtle motor dysfunction or small changes after treatment 15 and certainly cannot determine improvement in musical performance. Metabolic imaging studies using positron emission tomography PET studies are emerging as helpful ancillary tests, but these are invasive and expensive. Furthermore, while PET studies have implicated that primary dystonia may be associated with relative hypermetabolism in the putamen 16, there have been conflicting reports 17. Another major difficulty in the study of musicians dystonias has been lack of objective, quantifiable methods to assess degrees of dystonia severity or measure of treatment effects. Subjective and objective clinical rating scales with varying degrees of sophistication. Some subjective methods that have been used include subjective quantification usually using percentage improvement, also different various subjective rating scales using surveys. 