Article

People with Hereditary and Sporadic Spastic Parapresis (SP) walk with
a stiff legged gait characterised by a lack of knee flexion. OBJECTIVE: We
investigated the relationship between lower limb strength and stiffness and knee
flexion during swing phase while walking in 20 people with SP and 18 matched
controls. METHODS: Maximal isometric strength was measured using a dynamometer.
Passive stiffness and spasticity was assessed during motor-driven slow (5 degrees
/s) and fast (60 degrees /s) stretches at the ankle and knee while the subject
was relaxed or preactivating the muscle. Walking was assessed using 3D motion
analysis. RESULTS: Isometric muscle strength was decreased in people with SP with
over a 50% reduction in strength being found in the ankle dorsiflexors. Passive
stiffness, assessed during slow stretches, was 35% higher in the plantarflexors
in people with SP (P<0.05). Faster stretches induced large stretch evoked muscle
activity and over a 110% increase in stiffness at the ankle and knee in people
with SP reflecting the presence of spasticity (P<0.05). However, stretch reflex
size and stiffness was similar between the groups following identical stretches
of the pre-activated muscle (P>0.05). Lower knee flexion during swing phase was
associated with reduced knee flexion velocity at the end of stance phase which in
turn was associated with reduced plantarflexor strength and increased passive
stiffness in the knee extensors. CONCLUSIONS: The relative importance of muscle
paresis and passive stiffness in limiting walking in SP suggests that these
impairments should be the target of future therapies.
CI - Copyright (c) 2011 Elsevier B.V. All rights reserved.

Langue : ANGLAIS