Gait training facilitates central drive to ankle dorsiflexors in children with cerebral palsy

Abstract

Foot drop and toe walking are frequent concerns in children with cerebral palsy. The main underlying cause of these problems is early damage and lack of maturation of the corticospinal tract. In the present study we investigated whether 4 weeks of daily treadmill training with an incline may facilitate corticospinal transmission and improve the control of the ankle joint in children with cerebral palsy. Sixteen children with cerebral palsy (Gross Motor Classification System I:6, II:6, III:4) aged 5-14 years old, were recruited for the study. Evaluation of gait ability and intramuscular coherence was made twice before and twice after training with an interval of 1 month. Gait kinematics were recorded by 3D video analysis during treadmill walking with a velocity chosen by the child at the first evaluation. Foot pressure was measured by force sensitive foot soles during treadmill and over ground walking. EMG-EMG coherence was calculated from two separate electrode recordings placed over the tibialis anterior muscle. Training involved 30 min of walking daily on a treadmill with an incline for 30 days. Gait training was accompanied by significant increases in gait speed, incline on the treadmill, the maximal voluntary dorsiflexion torque, the number and amplitude of toe lifts late in the swing phase during gait and the weight exerted on the heel during the early stance phase of the gait cycle. EMG-EMG coherence in the beta and gamma frequency bands recorded from tibialis anterior muscle increased significantly when compared to coherence before training. The largest changes in coherence with training were observed for children <10 years of age. Importantly, in contrast to training-induced EMG increases, the increase in coherence was maintained at the follow-up measurement 1 month after training. Changes in the strength of coherence in the beta and gamma band were positively correlated with improvements in the subjects' ability to lift the toes in the swing phase. These data show that daily intensive gait training increases beta and gamma oscillatory drive to ankle dorsiflexor motor neurons and that it improves toe lift and heel strike in children with cerebral palsy. We propose that intensive gait training may produce plastic changes in the corticospinal tract, which are responsible for improvements in gait function.

Treadmill training with an incline reduces ankle joint stiffness and improves active range of movement during gait in adults with cerebral palsy

“…Chief among these are changes in the neural drive to the muscles and improved coordination of the muscle activity during gait. [13] Recently evidence of increased corticospinal drive to the tibialis anterior muscle following gait training has been provided, and it is likely that similar changes may contribute to the observed improvement in gait ability in our subjects. The complexity of gait requires a multifactorial analysis in order to reveal the significance of each of the possible contributing factors.…”

“…[11,12] Prior to this age, the gait pattern appears to be flexible and may also in children with CP be changed relatively easily through training. [13,14] This appears to relate to plastic changes in the central drive to the muscles and thus suggests that the central mechanisms involved in controlling gait are not so rigid despite the brain lesion that they cannot be trained. There is however also evidence that such plastic changes are less easy to induce in children older than 10 years.…”

“…There is however also evidence that such plastic changes are less easy to induce in children older than 10 years. [13] This may reflect that the central pathways are less plastic in older children and adults than in younger children. It seems likely that years of walking in a specific way make it more difficult to induce plastic changes and obtain training-induced changes in walking in adults.…”

“…Similar to our recent study in children with CP, [13,14] the adults were asked to train under supervision in their own home for 30-45 min every day. Whereas the children trained for 4 weeks, we asked the adults to train for 6 weeks.…”

EMG synchrony to assess impaired corticomotor control of locomotion after stroke

“…The same drive that elicits EEG-EMG synchrony can also lead to task-dependent synchronous activation among paired EMG recordings, such as synergistic muscles (as in the present study) or between different regions of a single muscle [Baker, Olivier, 1997, Grosse, Cassidy, 2002, Kilner, Baker, 1999, Neto, Baweja, 2010]. A number of prior studies have shown that central nervous system disease and functional deficits are linked to reduced EMG synchrony in gamma/Piper bands [Petersen et al, 2013, Willerslev-Olsen et al, 2015]. However, in the present study there was no significant group difference in EMG Piper synchrony during typical walking.…”