[Clinical rating scales for dystonia]

As long as the concept of dystonia, as currently defined and used, will encompass both a clinical syndrome, a genetic disease and a distinct clinical sign, rating scales devoted to dystonia will be facing a tremendous heterogeneity of phenomenology, including patients suffering from a very large spectrum of disease, exhibiting even contrasting features, namely, "mobile" dystonia as opposed to fixed postures. Indeed, relatively few clinical rating scales have been proposed in the evaluation of dystonia. This review constitutes an attempt to evaluate the position, in terms of reliability, pertinence, and usefulness of each of them. Since the worldwide diffusion of videotape recordings as a useful tool in the diagnosis and evaluation of Movement Disorders, scales have been developed aimed to yield a quantitative approach allowing the measurement of various therapeutic trials. In the setting of generalized dystonia, BFM and UDRS scales have been proposed, both of them being currently used. A recent study evaluating the clinimetric properties of these scales confirmed their usefulness in the setting of therapeutic trials. However, it is suggested that only a new scale, based on a two-axis analysis of dystonia, would be able to score both the "fixed posture" part and the "mobile" part of the so-called "dystonic" phenomenon.