Motor imagery ability in children with congenital hemiplegia: effect of lesion side and functional level.

In addition to motor execution problems, children with hemiplegia have motor planning deficits, which may stem from poor motor imagery ability. This study aimed to provide a greater understanding of motor imagery ability in children with hemiplegia using the hand rotation task. Three groups of children, aged 8-12 years, participated: right hemiplegia (R-HEMI; N=21), left hemiplegia (L-HEMI; N=19) and comparisons (N=21). All groups conformed to biomechanical limitations of the task, supporting the use of motor imagery, and all showed the expected response-time trade-off for angle. The general slowing of responses in the HEMI groups did not reach significance compared to their peers. The L-HEMI group were less accurate than the comparison group while the R-HEMI group were more variable in their performance. These results appeared to be linked to functional level. Using the Vineland Adaptive Behavior Composite, children were classified as low or normal functioning - of the seven classified as low function, six were in the L-HEMI group. Accuracy was lower in the low function subgroup, but this failed to reach significance with an adjusted critical value. However, there was a strong correlation between function level and mean accuracy. This indicates that motor imagery performance may be more closely linked to function level than to the neural hemisphere that has been damaged in cases of congenital hemiplegia. Function level may be linked to the site or extent of neural damage or the level of cortical reorganisation experienced and more attention should be paid to neural factors in future research.