title: Do skeletal muscle properties recover following repeat onabotulinum toxin A injections?
abstract: Onabotulinum toxin A (BTX-A) is a frequently used treatment modality to relax spastic muscles by preventing acetylcholine release at the motor nerve endings. Although considered safe, previous studies have shown that BTX-A injections cause muscle atrophy and deterioration in target and non-target muscles. Ideally, muscles should fully recover following BTX-A treatments, so that muscle strength and performance are not affected in the long-term. However, systematic, long-term data on the recovery of muscles exposed to BTX-A treatments are not available, thus practice guidelines on the frequency and duration of BTX-A injections, and associated recovery protocols, are based on clinical experience with little evidence-based information. Therefore, the purpose of this study was to investigate muscle recovery following a six months, monthly BTX-A injection (3.5 U/kg) protocol. Twenty seven skeletally mature NZW rabbits were divided into 5 groups: Control (n=5), zero month recovery - BTX-A+0M (n=5), one month recovery - BTX-A+1M (n=5), three months recovery - BTX-A+3M (n=5), and six months recovery - BTX-A+6M (n=7). Knee extensor strength, muscle mass and percent contractile material in injected and contralateral non-injected muscles was measured at each point of recovery. Strength and muscle mass were partially and completely recovered in injected and contralateral non-injected muscles for BTX-A+6M group animals, respectively. The percent of contractile material partially recovered in the injected, but did not recover in the contralateral non-injected muscles. We conclude from these results that neither target nor non-target muscles fully recover within six months of a BTX-A treatment protocol and that clinical studies on muscle recovery should be pursued.
authors: Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4.
authors: Rafael
authors: R
authors: Fortuna
authors: Monika
authors: M
authors: Horisberger
authors: Marco Aurélio
authors: MA
authors: Vaz
authors: Walter
authors: W
authors: Herzog
mesh_terms: D000818:Animals; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage*; D005260:Female; D005267:Femoral Nerve / Q000502:physiology; D006003:Glycogen / Q000502:physiology; D007273:Injections, Intramuscular; D018908:Muscle Weakness / Q000473:pathology / Q000503:physiopathology*; D009133:Muscular Atrophy / Q000473:pathology / Q000503:physiopathology*; D052097:Quadriceps Muscle / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D011817:Rabbits
chemical_list: D006003:Glycogen; D019274:Botulinum Toxins, Type A
keywords: Botox; Botulinum toxin; Cerebral palsy; Fibrosis; Muscle atrophy; Muscle recovery; Muscle weakness; NZW rabbits; Skeletal muscle; Spasticity