Abstract: Botulinum Neurotoxin A (BoNT-A) injections have been used for the treatment of muscle contractures and spasticity. This study assessed the influence of (BoNT-A) injections on passive biomechanical properties of the muscle-tendon unit. Mouse gastrocnemius muscle (GC) was injected with BoNT-A (n = 18) or normal saline (n = 18) and passive, non-destructive, in vivo load relaxation experimentation was performed to examine how the muscle-tendon unit behaves after chemical denervation with BoNT-A. Injection of BoNT-A impaired passive muscle recovery (15% vs. 35% recovery to pre-stretching baseline, p < 0.05) and decreased GC stiffness (0.531 ± 0.061 N/mm vs. 0.780 ± 0.037 N/mm, p < 0.05) compared to saline controls. The successful use of BoNT-A injections as an adjunct to physical therapy may be in part attributed to the disruption of the stretch reflex; thereby modulating in vivo passive muscle properties. However, it is also possible that BoNT-A injection may alter the structure of skeletal muscle; thus modulating the in vivo passive biomechanical properties of the muscle-tendon unit.
Keywords: Botulinum Neurotoxin; spasticity treatment; muscle tone; passive muscle biomechanics
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Haubruck, P.; Mannava, S.; Plate, J.F.; Callahan, M.F.; Wiggins, W.F.; Schmidmaier, G.; Tuohy, C.J.; Saul, K.R.; Smith, T.L. Botulinum Neurotoxin A Injections Influence Stretching of the Gastrocnemius Muscle-Tendon Unit in an Animal Model. Toxins 2012, 4, 605-619.
Haubruck P, Mannava S, Plate JF, Callahan MF, Wiggins WF, Schmidmaier G, Tuohy CJ, Saul KR, Smith TL. Botulinum Neurotoxin A Injections Influence Stretching of the Gastrocnemius Muscle-Tendon Unit in an Animal Model. Toxins. 2012; 4(8):605-619.
Haubruck, Patrick; Mannava, Sandeep; Plate, Johannes F.; Callahan, Michael F.; Wiggins, Walter F.; Schmidmaier, Gerhard; Tuohy, Christopher J.; Saul, Katherine R.; Smith, Thomas L. 2012. "Botulinum Neurotoxin A Injections Influence Stretching of the Gastrocnemius Muscle-Tendon Unit in an Animal Model." Toxins 4, no. 8: 605-619.