Test-retest reliability of corticokinematic coherence in young children with cerebral palsy: An observational longitudinal study

Objectives: To assess the test-retest reliability of the corticokinematic coherence (CKC), an electrophysiological marker of proprioception, in children with cerebral palsy (CP). Methods: Electroencephalography (EEG) signals from 15 children with unilateral or bilateral CP aged 23 to 53 months were recorded in two sessions 3 months apart using 128 -channel EEG caps. During each session, children's fingers were moved at 2 Hz by an experimenter, in separate recordings for the more-affected (MA) and lessaffected (LA) hands. The CKC was computed at the electrode and source levels, at movement frequency F0 (2 Hz) and its first harmonic F1 (4 Hz). A two-way mixed-effects model intraclass-correlation coefficient (ICC) was computed for the maximum CKC strength across electrodes at F0 and F1 obtained during the two sessions. Results: ICC of the CKC strength acquired from LA and MA hands pooled together were respectively 0.51 (95% CI: 0.30-0.68) at F0 and 0.96 (95% CI: 0.93-0.98) at F1. The mean distances separating the CKC peaks in the source space at the two evaluation times were in the order of a centimeter. Conclusion: CKC is a robust electrophysiologic marker to study the longitudinal changes in cortical processing of proprioceptive afferences in young children with CP.