AIM To investigate ataxia rating scales in children for reliability and the effect of age and sex. METHOD Three independent neuropaediatric observers cross-sectionally scored a set of paediatric ataxia rating scales in a group of 52 healthy children (26 males, 26 females) aged 4 to 16 years (mean age 10y 5mo SD 3y 11mo). The investigated scales involved the commonly applied International Cooperative Ataxia Rating Scale (ICARS), the Scale for Assessment and Rating of Ataxia (SARA), the Brief Ataxia Rating Scale (BARS), and PEGboard tests. We investigated the interrelatedness between individual ataxia scales, the influence of age and sex, inter-and intra-observer agreement, and test-retest reliability. RESULTS Spearman's rank correlations revealed strong correlations between ICARS, SARA BARS, and PEG-board test (all p<0.001). ICARS, SARA, BARS and PEG-board test outcomes were age-dependent until 12.5, 10, 11, and 11.5 years of age respectively. Intraclass correlation coefficients (ICCs) varied between moderate and almost perfect (interobserver agreement: 0.85, 0.72, and 0.69; intraobserver agreement: 0.92, 0.94, and 0.70; and test-retest reliability: 0.95, 0.50, and 0.71; for ICARS, SARA, and BARS respectively). Interobserver variability decreased after the sixth year of life.INTERPRETATION In healthy children, ataxia rating scales are reliable, but should include agedependent interpretation in children up to 12 years of age. To enable longitudinal interpretation of quantitative ataxia rating scales in children, European paediatric normative values are necessary.

In patients with EOA, the reliability of ataxia rating scales is high. However, the discriminative validity for 'ataxia' is low. For adequate interpretation of ataxia rating scale scores, application in uniform movement disorder phenotypes is essential.

View Supplementary Video 1 Background The Burke‐Fahn‐Marsden Dystonia Rating Scale is a universally applied instrument for the quantitative assessment of dystonia in both children and adults. However, immature movements by healthy young children may also show “dystonic characteristics” as a consequence of physiologically incomplete brain maturation. This could implicate that Burke‐Fahn‐Marsden scale scores are confounded by pediatric age. Objective In healthy young children, we aimed to determine whether physiologically immature movements and postures can induce an age‐related effect on Burke‐Fahn‐Marsden movement and disability scale scores. Methods Nine assessors specializied in movement disorders (3 adult neurologists, 3 pediatric neurologists, and 3 MD/PhD students) independently scored the Burke‐Fahn‐Marsden movement scale in 52 healthy children (4–16 years of age; 2 boys and 2 girls per year of age). Independent of that, parents scored their children's functional motor development according to the Burke‐Fahn‐Marsden disability scale in another 52 healthy children (4–16 years of age; 2 boys and 2 girls per year of age). By regression analysis, we determined the association between Burke‐Fahn‐Marsden movement and disability scales outcomes and pediatric age. Results In healthy children, assessment of physiologically immature motor performances by the Burke‐Fahn‐Marsden movement and disability scales showed an association between the outcomes of both scales and age (until 16 years and 12 years of age, β = −0.72 and β = −0.60, for Burke‐Fahn‐Marsden movement and disability scale, respectively [both P < 0.001]). Conclusions The Burke‐Fahn‐Marsden movement and disability scales are influenced by the age of the child. For accurate interpretation of longitudinal Burke‐Fahn‐Marsden Dystonia Rating Scale scores in young dystonic children, consideration of pediatric age‐relatedness appears advisory.