Article

Botulinum toxin type A manages spasticity disorders in neurological
central diseases. Some studies have reported that it might induce muscle changes.
METHODS: We present a literature review abiding by the PRISMA statement
guidelines. The purpose was to explore the structural and passive biomechanical
muscle properties after botulinum toxin type A injections in healthy and spastic
limb muscles, on animals and humans, as well as methods for evaluating these
properties. We searched the PubMed and Cochrane Library databases using the
following keywords: "Botulinum toxin" AND ("muscle structure" OR "muscle
atrophy") and, "Botulinum toxin" AND "muscle elasticity". RESULTS: From the 228
initially identified articles, 21 articles were included. Histological analyses
were performed, especially on animals. A neurogenic atrophy systematically
occurred. In humans, one year after a single injection, the histological recovery
remained incomplete. Furthermore, 2D ultrasound analyses showed a reduction of
the gastrocnemius thickness and pennation angle. MRI volumetric analysis
evidenced muscular atrophy six months or one year after a single injection.
Passive muscle stiffness depends on these structural changes. On the short term,
the biomechanical analysis showed an elastic modulus increase in animals whereas
no change was recorded in humans. On the short term, ultrasound elastography
imaging showed a decreased elastic modulus. DISCUSSION: To date, few data are
available, but all show a structural and mechanical muscle impact post
injections, specifically muscle atrophy which can linger over time. Further
studies are necessary to validate this element, and the possibility of change
must be taken into account particularly with repeated injections. Thus, in
clinical practice, 2D ultrasound and ultrasound elastography are two non-invasive
techniques that will help physicians to develop an efficient long term
monitoring.
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Langue : ANGLAIS