Objective: To test an age-independent video protocol in children with primary dystonia and to test the validity and utility of the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS), the Barry-Albright Dystonia Scale (BADS), and the Global Dystonia Rating Scale (GDRS).

Background: Quantification of dystonia severity is important for natural history studies of childhood-onset dystonia and for clinical trials of potential therapies. There are limited tools for use in pediatric dystonia.

Method: We developed a pediatric video examination protocol with input from the Executive Committee of the Dystonia Coalition and from experts in Pediatric Movement Disorders. We tested the protocol in 16 individuals with dystonia and normal cognition, age 4-16 years. Dystonia etiologies included genetic (DYT1, DYT4, DYT5, DYT6, or DYT11), putamen infarction, or idiopathic. However, of 16 individuals, only 10 had “isolated dystonia” (only 4 individuals had no tremor). The others had co-existing ataxia (DYT4), myoclonus (DYT11), chorea (idiopathic), or parkinsonism (DYT5) that prevented precise scoring of dystonia separate from co-existing movement disorders.

Results: Severity ranges in the sample were: BFMDRS 4-80 (Median 24.5); BADS 4-19 (Median 11); GDRS 11-78 (Median 39). The BADS had an apparent ceiling effect despite the maximum score in our sample (19) being less than the theoretical maximum of 30. A preliminary correlation analysis was performed to explore cross-validation (Figure). There was a significant positive correlation between all paired comparisons. Based on these, the BADS is unlikely to be superior to the other two scales. This may reflect the fact that the BADS was designed for use in children with dystonia in the setting of cerebral palsy. It may also reflect the high threshold (loss of function) to score a severity of “4” for any body part. Ease of use was highest for the GDRS, which is consistent with prior studies in adult-onset primary dystonia.

Conclusion: With recent advances in diagnostics, it is apparent that there is both substantial genetic heterogeneity and substantial genetic pleiotropy in childhood-onset dystonia. Furthermore, only a minority of children with dystonia that have truly isolated dystonia. Future natural history studies in childhood dystonia should focus on specific entities and should include tools that assess multiple movement disorders, discriminate among coexisting movement disorders, or a combination.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/comparison-of-dystonia-rating-scales-in-children-with-primary-isolated-dystonia/