Article

Stiffness and shortening of the calf muscle due to neural or mechanical
factors can profoundly affect motor function.
The aim of this study was to
investigate non-neurally mediated calf-muscle tightness in children with cerebral
palsy (CP) before and after botulinum toxin type A (BoNT-A) injection. Method
Sixteen children with spastic CP (seven females, nine males; eight at Gross Motor
Function Classification System level I, eight at level II; age range 4-10y) and
calf muscle spasticity were tested before and during the pharmaceutically active
phase after injection of BoNT-A. Measures of passive muscle compliance and
viscoelastic responses, hysteresis, and the gradient of the torque-angle curve
were computed and compared before and after injection. Results Although there was
a slight, but significant increase in ankle range of motion after BoNT-A
injection and a small, significant decrease in the torque required to achieve
plantigrade and 5 degrees of dorsiflexion, no significant difference in
myotendinous stiffness or hysteresis were detected after BoNT-A injection.
Interpretation Despite any effect on neurally mediated responses, the compliance
of the calf muscle was not changed and the muscle continued to offer significant
resistance to passive motion of the ankle. These findings suggest that additional
treatment approaches are required to supplement the effects of BoNT-A injections
when managing children with calf muscle spasticity.
CI - (c) The Authors. Developmental Medicine & Child Neurology (c) 2011 Mac Keith
Press.

Langue : ANGLAIS