Contribution of corticospinal drive to ankle plantar flexor muscle activation during gait in adults with cerebral palsy
- 69 Downloads
Impaired plantar flexor muscle activation during push-off in late stance contributes importantly to reduced gait ability in adults with cerebral palsy (CP). Here we used low-intensity transcranial magnetic stimulation (TMS) to suppress soleus EMG activity during push-off as an estimate of corticospinal drive in CP adults and neurologically intact (NI) adults. Ten CP adults (age 34 years, SD 14.6, GMFCS I–II) and ten NI adults (age 33 years, SD 9.8) walked on a treadmill at their preferred walking speed. TMS of the leg motor cortex was elicited just prior to push-off during gait at intensities below threshold for motor-evoked potentials. Soleus EMG from steps with and without TMS were averaged and compared. Control experiments were performed while standing and in NI adults during gait at slow speed. TMS induced a suppression at a latency of about 40 ms. This suppression was similar in the two populations when differences in control EMG and gait speed were taken into account (CP 18%, NI 16%). The threshold of the suppression was higher in CP adults. The findings suggest that corticospinal drive to ankle plantar flexors at push-off is comparable in CP and NI adults. The higher threshold of the suppression in CP adults may reflect downregulation of cortical inhibition to facilitate corticospinal drive. Interventions aiming to facilitate excitability in cortical networks may contribute to maintain or even improve efficient gait in CP adults.
KeywordsCerebral palsy Corticospinal drive Plantar flexor muscles Push-off
The study was supported by the Elsass foundation, Charlottenlund, Denmark. The foundation was not involved in the conduct or decision making regarding the work presented in the paper. We are grateful to all the participants for all their interest in the study.
Compliance with ethical standards
Conflict of interest
No conflicts of interest, financial or otherwise, are declared by the authors.
- Drew T, Jiang W, Kably B, Lavoie S (1996) Role of the motor cortex in the control of visually triggered gait modifications. Can J Physiol Pharmacol 74:426–442Google Scholar
- Lunenburger L, Colombo G, Riener R, Dietz V (2004) Biofeedback in gait training with the robotic orthosis Lokomat. Conf Proc IEEE Eng Med Biol Soc 7:4888–4891Google Scholar
- Parvin S, Taghiloo A, Irani A, Mirbagheri MM (2017) Therapeutic effects of anti-gravity treadmill (AlterG) training on reflex hyper-excitability, corticospinal tract activities, and muscle stiffness in children with cerebral palsy. IEEE Int Conf Rehabil Robot 2017:485–490Google Scholar
- Zuur AT (2013) Human locomotion and the motor cortex: drive to the motoneuron and the role of afferent input. PhD Thesis, Aalborg UniversityGoogle Scholar