Article

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.

Langue : ANGLAIS

Tiré à part : OUI