Sensory feedback to ankle plantar flexors is not exaggerated during gait in spastic children with cerebral palsy

TY - JOUR

T1 - Sensory feedback to ankle plantar flexors is not exaggerated during gait in spastic children with cerebral palsy

AU - Willerslev-Olsen, Maria

AU - Andersen, Jacob Buus

AU - Sinkjær, Thomas

AU - Nielsen, Jens Bo

N1 - CURIS 2014 NEXS 071

PY - 2014/2/15

Y1 - 2014/2/15

N2 - It is still widely believed that exaggerated stretch reflexes and increased muscle tone in ankle plantar flexors contribute to reduced ankle joint movement during gait in children with cerebral palsy (CP). However, no study has directly measured stretch reflex activity during gait in these children. We investigated sensory feedback mechanisms during walking in 20 CP children and 41 control children. Stretch responses in plantar flexor muscles evoked in stance showed an age-related decline in control but not CP children. In swing the responses were abolished in control children, but significant responses were observed in 14 CP children. This was related to reduced activation of dorsiflexors in swing. Removal of sensory feedback in stance produced a drop in soleus activity of a similar size in control and CP children. Soleus activity was observed in swing to the same extent in control and CP children. Removal of sensory feedback in swing caused a larger drop in soleus activity in control children than in CP children. The lack of age-related decline in stretch reflexes and the inability to suppress reflexes in swing is likely related to lack of maturation of corticospinal control in CP children. Since soleus activity was not seen more frequently than in control children in swing and since sensory feedback did not contribute more to their soleus activity, spasticity is unlikely to contribute to foot drop and toe walking. We propose that altered central drive to the ankle muscles and increased passive muscle stiffness are the main causes of foot drop and toe walking.

AB - It is still widely believed that exaggerated stretch reflexes and increased muscle tone in ankle plantar flexors contribute to reduced ankle joint movement during gait in children with cerebral palsy (CP). However, no study has directly measured stretch reflex activity during gait in these children. We investigated sensory feedback mechanisms during walking in 20 CP children and 41 control children. Stretch responses in plantar flexor muscles evoked in stance showed an age-related decline in control but not CP children. In swing the responses were abolished in control children, but significant responses were observed in 14 CP children. This was related to reduced activation of dorsiflexors in swing. Removal of sensory feedback in stance produced a drop in soleus activity of a similar size in control and CP children. Soleus activity was observed in swing to the same extent in control and CP children. Removal of sensory feedback in swing caused a larger drop in soleus activity in control children than in CP children. The lack of age-related decline in stretch reflexes and the inability to suppress reflexes in swing is likely related to lack of maturation of corticospinal control in CP children. Since soleus activity was not seen more frequently than in control children in swing and since sensory feedback did not contribute more to their soleus activity, spasticity is unlikely to contribute to foot drop and toe walking. We propose that altered central drive to the ankle muscles and increased passive muscle stiffness are the main causes of foot drop and toe walking.

U2 - 10.1152/jn.00372.2013

DO - 10.1152/jn.00372.2013

M3 - Journal article

C2 - 24225545

SN - 0022-3077

VL - 111

SP - 746

EP - 754

JO - Journal of Neurophysiology

JF - Journal of Neurophysiology

IS - 4

ER -