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

Abstract

Objective: To introduce the Windmill-task, a new objective assessment to quantify the presence of mirror movements (MMs) in children with unilateral cerebral palsy (uCP). In children with uCP MMs 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 data across studies is problematic. Design: Prospective, observational, cohort pilot study. Setting: Children with uCP were recruited from Monash Children’s Hospital, Melbourne, Australia as a convenience sample from a cohort of children previously recruited for a larger study. Participants: Prospective cohort of 23 children with uCP (age range:6-15y, mean age=10y5m, SD=2y7m). Inclusion criteria were diagnosis of uCP with a Manual Ability Classification System (MACS)20 level I-III. Interventions: Not applicable. Main Outcome Measure(s): The concurrent validity of the Windmill-task is assessed and sensitivity and specificity for MM detection is compared between both assessments. To assess the concurrent validity, Windmill-data are compared to W&T-data using Spearman-rank (rho) correlations for two conditions (affected-hand-moving vs. less-affected-hand-moving). Sensitivity and specificity are compared by presenting the mean percentage of children being assessed inconsistently across both assessments. Results: Outcomes of both assessments correlated significantly (affected-hand-moving: rho=.520;p=.005; less-affected-hand-moving: rho=.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 two 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 additional advantage of sensitivity to detect MMs.