The role of botulinum toxin injections in the management of muscle overactivity of the lower limb

Abstract

Muscle overactivity is common in patients with adult onset central nervous system damage. It can produce significant disablement in conjunction with other impairments such as adaptive soft tissue shortening and loss of muscle strength. Muscle overactivity is not evenly distributed throughout the body; across joints there is frequently imbalance between agonist and antagonist, producing abnormal joint postures and movement patterns. Due to the asymmetric nature of the abnormal activity across joints, in general we recommend local treatment targeting the more overactive of the two agonists, rather than systemic treatment. Considerable experience with the use of botulinum toxin, both serotypes A and B, in the treatment of muscle overactivity has been accumulated in the last two decades through pragmatic clinical practice and open label studies, supported by an increasing number of randomized controlled trials. In most cases, it is important to use botulinum toxin injection for treatment of muscle overactivity in the setting of wider rehabilitation goals and interventions. Focal and partial blocks with botulinum toxin should be used as a component of a general neurorehabilitation programme rather than as an alternative to other treatments. We review the evidence supporting the use of botulinum toxin to treat muscle overactivity in the lower limb, present practical guidelines on when and how to use botulinum toxin and provide direction for future research.

Efficacy of Botulinum Toxin A Treatment for Pes Varus during Gait

“…A specific and sensitive outcome measure is needed because the duration and degree of benefit of BoNTA injection vary across individuals. 22 Three-dimensional analysis can detect even small changes in motion that are impossible to identify by observational analysis, and a 3-dimensional motion analysis system is useful for objectively evaluating changes in motion after BoNTA injection. The effect on gait velocity by BoNTA injection to the calf muscles of patients with hemiplegia remains controversial.…”

Onabotulinumtoxin-A injection for disabling lower limb flexion in hemiplegic patients

“…With respect to the lower limb, most published studies have considered distal deformation (i.e. equinovarus) and, more rarely, knee deformation (or stiff knee) (Gracies, Singer, & Dunne, 2007;Bleyenheuft, Cockx, Caty, Stoquart, Lejeune, & Detrembleur, 2009). …”

Botulinum Toxin as a Neuro-Relearning Drug Tool in Motor Paralytic Disorders

“…This causes impaired smooth recruitment -derecruitment of pool/s and thus cause excitation-inhibition imbalance between synergists-antagonists [6,20]. In the paralytic patient this manifests as different degrees of spasticity / overactivity of individual limb muscles [12].…”

“…The author's recent [4,6] and this paper explain how this plasticity could be harnessed and BoTx used as a neuro-relearning tool to improve recovery in motor paralytic disorders of various etiologies. The beneficial effect of BoTx on spasticity relief is generally attributed to the altered afferent signals from muscle spindles and tendon organs of the injected muscle/s on to its synergists-antagonists and the ensuing sensory plasticity at spinal-supraspinal levels [7][8][9][10][11][12]. However, it is not sensory plasticity alone, but the far reaching plasticity effects at the motor system [4-6] that together bring these transient benefits in spastic muscles.…”