Windmill-task as a new quantitative and objective assessment for mirror movements in unilateral cerebral palsy: a pilot study

Objective To introduce the Windmill-task, a new objective assessment tool to quantify the presence of mirror movements (MMs) in children with unilateral cerebral palsy (UCP), which are typically assessed with the observation-based Woods and Teuber scale (W&T). Design Prospective, observational, cohort pilot study. Setting Children’s hospital. Participants Prospective cohort of children (N=23) with UCP (age range, 6–15y, mean age, 10.5±2.7y). Interventions Not applicable. Main Outcome Measures The concurrent validity of the Windmill-task is assessed, and the sensitivity and specificity for MM detection are compared between both assessments. To assess the concurrent validity, Windmill-task data are compared with W&T data using Spearman rank correlations (ρ) for 2 conditions: affected hand moving vs less affected hand moving. Sensitivity and specificity are compared by measuring the mean percentage of children being assessed inconsistently across both assessments. Results Outcomes of both assessments correlated significantly (affected hand moving: ρ=.520; P=.005; less affected hand moving: ρ=.488; P=.009). However, many children displayed MMs on the Windmill-task, but not on the W&T (sensitivity: affected hand moving: 27.5%; less affected hand moving: 40.6%). Only 2 children displayed MMs on the W&T, but not on the Windmill-task (specificity: affected hand moving: 2.9%; less affected hand moving: 1.4%). Conclusions The Windmill-task seems to be a valid tool to assess MMs in children with UCP and has an additional advantage of sensitivity to detect MMs