title: Effect of muscle activity and botulinum toxin dilution volume on muscle paralysis.
abstract: The purpose of this study was to evaluate the effects of botulinum toxin A (BTX-A, Botox) dilution volume and post-injection exercise with electrical stimulation on muscle paralysis. We injected 10 units of BTX-A diluted with 0.1 ml (B1, n=8) or 0.5 ml (B5, n=8) normal saline into both gastrocnemius muscles of 16 New Zealand white rabbits; two controls received no BTX-A. After BTX-A injection, all rabbits received calf muscle stretching exercise and electrical stimulation for 2 hours on the left leg. The compound muscle action potential (CMAP) decrease was most pronounced at 1 week and progressive recovery was observed (i.e. recovery from paralysis, increase of CMAP). There was a significant decrease of CMAP amplitudes in the B5 group compared with the B1 group at week 1 and week 4 (p<0.001). Left limbs with stretching exercise and electrical stimulation showed lower CMAP amplitudes compared with control right limbs of all rabbits. To maximize the muscle paralysis effect of BTX-A, increasing dilution volume and performing post-injection stretching exercise with electrical stimulation may be a promising strategy for increasing the beneficial effect of BTX-A treatment. Future studies are needed to investigate the clinical application of this finding.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. hskim@smc.samsung.co.kr
authors.forename: Hyeon Sook
authors.initials: HS
authors.lastname: Kim
authors.forename: Ji Hye
authors.initials: JH
authors.lastname: Hwang
authors.forename: Soon Tak
authors.initials: ST
authors.lastname: Jeong
authors.forename: Yong Taek
authors.initials: YT
authors.lastname: Lee
authors.forename: Peter K W
authors.initials: PK
authors.lastname: Lee
authors.forename: Yeon-Lim
authors.initials: YL
authors.lastname: Suh
authors.forename: Jong Sup
authors.initials: JS
authors.lastname: Shim
mesh_terms: D000818:Animals; D019274:Botulinum Toxins, Type A / Q000627:therapeutic use*; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D007273:Injections, Intramuscular; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology*; D009465:Neuromuscular Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D010243:Paralysis / Q000188:drug therapy* / Q000503:physiopathology*; D011817:Rabbits
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A