Dynamic spasticity in children with Cerebral Palsy

Spasticity is defined as velocity dependent hypertonia (Lance, 1990), and is
apparent in 80% of children with Cerebral Palsy. In clinical practice,
spasticity is measured using passive muscle tests such as the (Modified)
Ashworth Scale or the (Modified) Tardieu Scale. However, it is difficult to
determine the precise effect of spasticity on gait. Crenna et al. (Crenna et
al., 1992; Crenna, 1998) introduced an interesting idea to look at spasticity
effects during gait, by looking at the relationship between muscle lengthening
velocity and muscle electromyographic (EMG) activity. They found that in
children with CP the coupling between muscle lengthening velocity and EMG
activity is often increased compared to normal. However, they did not translate
this idea into a workable algorithm, a measure that is (physiologically)
meaningful; that can be tested; and is clinically applicable. Therefore we will
set up a study to examine dynamic spasticity, i.e. the spasticity effects
during gait, in a group of children with spastic CP

To determine to what extent dynamic spasticity can be recognized and quantified
in the gait pattern of children with spastic CP and to develop a meaningful and
(clinically) applicable measure of dynamic spasticity

(Pilot) study to compare groups: CP versus normal.

All subjects will be measured twice in the same way. They will get physical
examination to measure spasticity in a standard clinical way. Then instrumented
gait analysis will be performed. Subjects will walk on a 6m walkway at
comfortable walking speed, at a slow and a fast speed. 3D kinematics, kinetics
and electromyography will be measured.

The extensive data that will be collected are expected to give a better insight
and understanding of gait deviations than regular clinical examination will do.
In the (near) future, these additional data can lead to better diagnosis and
treatment.

The additional risks of the current study for the subjects are negligible and
the burdens minimal. The measurements are non-invasive. Subjects will have to
walk on a walkway with measurement tools (EMG electrodes and kinematic markers)
attached to their bodies. More markers and cables will be used than during
standard clinical practice, this may somewhat increase the burden of the
measurements compared to regular treatment. This is also the case because it
will take some more time to attach the markers, which will ask for patients of
the subjects. It should be noted that the current experimental set-up is
comparable to standard gait analysis as applied in many gait laboratories all
over the world for standard clinical practice.

We believe the benefits clearly outweigh the risks and burdens for the
subjects.