Assessing corticospinal tract (re)organization in unilateral cerebral palsy based on mirror movement characteristics and diffusion measures

Introduction Structural reorganization of the corticospinal tract (CST) forms a primary source of variability amongst children with unilateral cerebral palsy (uCP). However, the CST-wiring pattern is not immediately apparent from the child’s clinical presentation. Here we test the value of mirror movements (MM) in the paretic hand with respect to CST wiring, and whether diffusion measures of CST structural integrity aid further classification. Patients and methods We assessed MM, CST-wiring and structural integrity in 26 children with uCP (age 5-22 years; 15 boys; 13 right-sided; MACS I=7, II=9, III=10). MM in the paretic hand were quantified using a repetitive squeezing task with force handles. MM characteristics and CST diffusion measures were used to classify children into 3 MM-groups (k-means clustering), which were compared against their individual CST-wiring pattern (based on transcranial magnetic stimulation, TMS). Results Contralateral, ipsilateral, and bilateral CST-wiring was seen in 8, 11, and 7 children respectively. The k-means clustering based on MM-strength and MM-synchronization grouped the children into ‘low’ (n=10), ‘moderate’ (n=11) and ‘strong’ (n=5) MM. Comparison against the individual child’s wiring pattern showed high sensitivity (100%), specificity (89%) and accuracy (92%). However, within the ‘moderate’ and ‘strong’ MM-groups, classification accuracy was only 61% for ipsilateral vs. bilateral CST-wiring. This might be further improved based on CST diffusion measures. Conclusion We provide first evidence of the value of MM-strength and MM-synchronization in the paretic hand with respect to unraveling CST-(re)organization. Knowledge of structural integrity of the CST might help to further dissociate ipsilateral vs. bilateral CST-wiring patterns.status: accepte