The evaluation of dystonia requires a reliable rating scale. The widely used Fahn-Marsden Scale (F-M) has not been sufficiently tested across multiple centers and investigators. The Dystonia Study Group developed the Unified Dystonia Rating Scale (UDRS) and a Global Dystonia Rating Scale (GDS) to serve as instruments to assess dystonia severity. In this study, 25 dystonia experts evaluated the UDRS, F-M, and GDS for internal consistency and reliability. One hundred dystonia patients were videotaped using a standardized videotape protocol. Each examiner rated 20 patients using the UDRS, F-M, and GDS in random order. The examiner then assessed each scale for ease of use. Statistical analysis used Cronbach's alpha, intraclass correlation coefficients (ICC), generalized weighted kappa statistic, and Kendall's coefficient of concordance. The UDRS, F-M, and GDS showed excellent internal consistency (Cronbach's alpha 0.89-0.93) and good to excellent correlation among the raters (ICC range from 0.71-0.78). Inter-rater agreement was fair to excellent (Kendall's 0.54-0.87; kappa 0.37-0.91) being lowest for eyes, jaw, face, and larynx. The modifying ratings (Duration in the UDRS and Provoking Factor in the F-M) showed less agreement than the motor severity ratings. Among scales, the total scores correlated (Pearson's r, 0.977-0.983). Overall, 74% of raters found the GDS the easiest to apply. The GDS with its simplicity and ease of application may be the most useful dystonia rating scale.

Although dyskinesia is a frequent and important problem in Parkinson's disease (PD), a reliable assessment measure has not been thoroughly developed and tested. We modified the Obeso dyskinesia scale to create an objective rating scale for dyskinesia assessment during activities of daily living. Thirteen physicians and 15 study coordinators involved in a clinical trial independently reviewed videotape segments of PD patients performing three tasks: walking, putting on a coat, and lifting a cup to the lips for drinking. Raters evaluated the severity of worst dyskinesia seen, the types of all dyskinesias seen, and the type of dyskinesia most associated with motoric disability. For all assessments, the total group showed statistically significant inter- and intrarater reliability. Physicians had a higher consistency than did coordinators, but for most measures the difference was not statistically significant. Physicians and coordinators found the scale easy to use and especially practical for rating dyskinesia severity and for identifying the most disabling dyskinesia. Dyskinesias can be assessed in clinical trials and warrant regular documentation.

The Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) assesses the character and severity of cervical dystonia (CD). We developed a teaching tape of the TWSTRS scoring for the motor symptoms of CD. The tape provides investigators with visual representations of each component of the motor section of the TWSTRS as agreed upon by three independently scoring raters. The rate of agreement for the nondichotomous components was always significant, with a Kendall's coefficient of concordance W ranging between 0.98 and 0.76 (p < 0.01 for all measures). For the two dichotomous components, a weighted kappa coefficient was also significant at 0.86 for lateral shift and 0.89 for sagittal shift (p < 0.01 for both measures). Scale deficiencies identified by the raters were an explicit definition of midline for assessment of range of motion, the absence of a separate scoring category assessing dystonic tremor, and the specification of duration for the effect of sensory tricks. These observations should be taken into account in future revisions of the TWSTRS and in refinements of other rating scales for CD.