Introduction of the Windmill-task: A new quantitative and objective method to assess mirror movements in children with unilateral cerebral palsy

Introduction In children with unilateral cerebral palsy (uCP) mirror movements are frequently observed. They are typically assessed with the observation-based Woods and Teuber scale (W&T). However, due to its subjective nature and variable administration, interpretation of W&T data across studies of uCP is problematic. We introduce the Windmill-task, a new objective assessment to quantify the presence of mirror movements. The concurrent validity of the Windmill-task is assessed and sensitivity and specificity for mirror movement detection between both assessments (W&T and Windmill-task) is compared. Patients and method To assess the concurrent validity, Windmill-data from 23 children with uCP (Mage=10y,5m, range: 6y,4m – 14y,11m, MACS I&II) are compared to W&T-data using Spearman-rank (rho) correlations for two conditions (affected-hand-actively-moving vs. less-affected-hand-actively-moving). Sensitivity and specificity are compared by presenting the mean percentage of children being assessed inconsistently across both assessment tools. Results Outcomes of both assessments correlate significantly (affected-hand-actively-moving: rho=.520; p=.005; less-affected-hand-actively-moving: rho=.488;p=.009). However, many children display mirror movements on the Windmill-task, but not on the W&T (sensitivity: affected-hand-actively-moving: 27.5%; less-affected-hand-actively-moving: 40.6%). Only one child displays mirror movements on the W&T, but not on the Windmill-task (specificity). Conclusion The Windmill-task is a valid tool to assess mirror movements in children with uCP and shows additional advantages especially related to the sensitivity of detecting mirror movements. The latter was particularly present when assessing mirror movements in the AH (less-affected-hand-actively-moving).status: accepte