Scales for hyperkinetic disorders: a systematic review

Hyperkinetic movement disorders represent a heterogeneous group of disorders in which involuntary movements are the prevalent clinical symptoms. The five main categories of hyperkinetic disorders are tremor, dystonia, tics, myoclonus and drug-induced dyskinesia.The severity of hyperkinetic disorders is assessed by all clinicians when they examine a patient; quantifying the severity also provides a means of studying the natural history of a given disorder and the possible effect of new therapeutic interventions. This means that good rating instruments are required in both everyday practice and experimental settings. Unfortunately, the clinical evaluation of these disorders is complicated by the inherent nature and variability over time of involuntary movements. A number of scales have been proposed over the years to study the various hyperkinetic disorders. The aim of this review is to systematically identify all the clinical scales that have been proposed and to classify them according to the criteria developed by the Movement Disorder Society (MDS) task force for rating scales in Parkinson's disease. On the basis of this methodology, a scale may be defined as 'Recommended', 'Suggested' or 'Listed' in decreasing order of value.We found that, although numerous scales aimed at assessing hyperkinetic disorders have been published, their variability in terms of clinimetric properties, availability and effort required to administer them is high. In this evaluation, we identified scales defined as 'Recommended' for the assessment of all forms of hyperkinetic disorders. The situation highlighted by our analysis varies considerably, with several 'Recommended' scales being available for some conditions such as tics or dystonia, but only one being available for myoclonus. This gap needs to be filled by the scientific community through both the development of new clinical tools and the refinement of existing ones.