Do skeletal muscle properties recover following repeat onabotulinum toxin A injections?

Muscle histopathology in children with spastic cerebral palsy receiving botulinum toxin type A

“…For example, Fortuna and colleagues reported data in rabbits that showed significantly decreased muscle strength and mass of the vastus lateralis, rectus femoris, and vastus medialis 1 month after initial BoNTA injections. Further, these decreases continued with repeat injections . Similar atrophy and decreases in muscle mass have also been reported in the plantaris, soleus, and gastrocnemius muscles of rats 10 weeks post‐BoNTA .…”

Recovery of neuronal and network excitability after spinal cord injury and implications for spasticity

“…Botulinum toxin produced stable improvements in upper-extremity function, hygiene and decreased pain in ~65% of individuals with SCI (Marciniak et al, 2008). However, the duration of effect is only 2–4 months, requiring repeated injections which may further increase the amount of non-contractile tissue within the target muscle (Fortuna et al, 2013). Dantrolene sodium is an oral antispastic that affects the excitation-contraction coupling in skeletal muscles by decreasing the release of calcium from the sarcoplasmic reticulum through blocking the ryanodine receptor (Britt, 1984; Krause et al, 2004; Lanner et al, 2010).…”

Muscle volume alterations after first botulinum neurotoxin A treatment in children with cerebral palsy: a 6‐month prospective cohort study

“…With muscle volume in children with CP reduced compared with their typically developing counterparts, research has focused on the potential for BoNT‐A exposure to further reduce muscle volume. Data from animal and healthy adult human studies have both found muscle atrophy (reduction in absolute muscle volume) in response to BoNT‐A exposure . Muscle atrophy may significantly affect the muscle's functional ability.…”

“…Although atrophy of the injected muscle is consistently found in the first 6 months after exposure, there is no clear consensus on the expected magnitude of this reduction. This variation may stem from multiple factors, including measurement techniques, normalization, muscles assessed, ambulation status, BoNT‐A dosage, and previous BoNT‐A exposure (which has been found to be an important factor in predicting atrophy in animal models) . While some of these factors were well described in the aforementioned studies, others were not, clouding interpretation.…”