Study of the Effect of Botulinum Toxin Injection in Rectus Femoris and Triceps on the Length and the Strength During Locomotion in Chronic Hemiparetic Patients

Double Blind Randomized Controlled Study of the Effect of Botulinum Toxin Injection in Rectus Femoris and Triceps on the Length and the Strength of These Muscles During Locomotion in Chronic Hemiparetic Patients

The aim of this randomized controlled study is to quantify the modification during locomotion of chronic hemiparetic patients of the strength and the length of Rectus Femoris and Triceps Surae induced by botulinum toxin injection type A.

The main hypotheses of this study based on previous studies are that botulinum toxin injection increases on one hand the length of the muscle injected during gait and on the other hand decreased the strength of the muscles injected.

The investigators also hypothesized that botulinum toxin injection improved the strength of the antagonist muscles and normalized the pattern of strength of the muscles injected during gait.

The aim of this study is to compare versus placebo the effects of BTX-A injection on :

• the maximal length of the muscles injected during gait
• the maximal lengthening velocity of the muscles injected during gait
• the maximal strength of muscles injected during gait
• the inter-limb coordination assessed by continuous relative phase
• the kinematic parameters such as peak knee flexion during swing phase of the gait cycle and peak ankle dorsiflexion during stance phase.

To that end each patient included in the study will be assessed before injection, one month after the BTX-A injection and 3 months after BTX-A injections.

All patients will underwent a clinical examination, a 3D gait analysis and a isokinetic dynamometer analysis.

The comparison of the results in the group treated by BTX-A will permit to show that one month after BTX-A injection peak length during gait of muscles injected, maximal lengthening velocity peak knee flexion during swing phase and peak ankle dorsiflexion increase significantly.

It will also permit to show that the maximal strength of muscles injected decreases whereas the strength of antagonist increases It will also permit to demonstrate that multisite BTX-A injection improve coordination of paretic and non paretic lower limb the inter-group comparison will permit to demonstrate that these modification are mainly due to multisite BTX-A injections.

Inclusion Criteria:

• men or women aged > 18 ans
• unilateral stroke more than 6 months
• ability to walk 10 meters without assistive device
• decrease of peak knee flexion in swing phase of the gait cycle due to a spasticity of Rectus femoris muscle
• plantarflexion in swing phase of the gait cycle due to a spasticity of the triceps surae
• informed consent approved
• oral contraception

Exclusion Criteria:

• Aphasia
• anteriority of lower limb surgery less than 6 months
• underlying disease
• pre-existing neuro-muscular disorders
• pregnancy
• absence of oral contraception
• last botulinum toxin injection < 3months
• hypersensitivity reactions
• co-administration of aminoglycosides