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

To assess the test-retest reliability of the corticokinematic coherence (CKC), an electrophysiological marker of proprioception, in children with cerebral palsy (CP). 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 less-affected (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. 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. CKC is a robust electrophysiologic marker to study the longitudinal changes in cortical processing of proprioceptive afferences in young children with CP.