Abstract
Spasticity is a common disabling disorder in adult subjects suffering from stroke, brain injury, multiple sclerosis (MS) and spinal cord injury (SCI). Spasticity may be a disabling symptom in people during rehabilitation and botulinum toxin type A (BTX-A) has become the first-line therapy for the local form. High BTX-A doses are often used in clinical practice. Advantages and limitations are debated and the evidence is unclear. Therefore, we analysed the efficacy, safety and evidence for BTX-A high doses. Studies published from January 1989 to February 2020 were retrieved from MEDLINE/PubMed, Embase, Cochrane Central Register. Only obabotulinumtoxinA (obaBTX-A), onabotulinumtoxinA (onaBTX-A), and incobotulinumtoxinA (incoBTX-A) were considered. The term “high dosage” indicated ≥ 600 U. Thirteen studies met the inclusion criteria. Studies had variable method designs, sample sizes and aims, with only two randomised controlled trials. IncoBTX-A and onaBTX-A were injected in three and eight studies, respectively. BTX-A high doses were used predominantly in treating post-stroke spasticity. No studies were retrieved regarding treating spasticity in MS and SCI. Dosage of BTX-A up to 840 U resulted efficacious and safety without no serious adverse events (AEs). Evidence is insufficient to recommend high BTX-A use in clinical practice, but in selected patients, the benefits of high dose BTX-A may be clinically acceptable.
Highlights
Spasticity is a common disabling disorder in adult subjects suffering from upper motor neuron syndrome (UMNS) and generally develops after lesions of the central nervous system (CNS) such as those caused by stroke, brain injury, spinal cord injury (SCI), multiple sclerosis (MS) and cerebralToxins 2020, 12, 315; doi:10.3390/toxins12050315 www.mdpi.com/journal/toxinsToxins 2020, 12, 315 palsy (CP)
The benefits of high dose botulinum toxin type A (BTX-A) may outweigh the risks of adverse events (AEs) and may be clinically acceptable
Kirshblum et al reported an increase in AEs but suggested that the benefits of high dose Botulinum neurotoxin (BTX)-A may outweigh the risks of AEs and may be clinically acceptable in certain patients [29]
Summary
Spasticity is a common disabling disorder in adult subjects suffering from upper motor neuron syndrome (UMNS) and generally develops after lesions of the central nervous system (CNS) such as those caused by stroke, brain injury, spinal cord injury (SCI), multiple sclerosis (MS) and cerebralToxins 2020, 12, 315; doi:10.3390/toxins12050315 www.mdpi.com/journal/toxinsToxins 2020, 12, 315 palsy (CP). Spasticity is a motor disorder characterised by a velocity-dependent increased resistance to passive limb movement with increased muscle tone and hyperactive reflexes [1]. To reduce its negative impact and to improve functional limitations, several therapeutic strategies, including non-pharmacological and pharmacological strategies, have been proposed. Spasticity can occur among the spectrum of UMNS symptoms that include weakness, fatigue, spasms and clonus and, the clinical picture can be variable depending on the sites involved and extension or neuronal tissue damage. Spasticity can be segmental, involving limited sites of the body, or generalised, involving both the upper and lower limbs. Botulinum toxin type A (BTX-A), by inhibiting the release of pre-synaptic acetylcholine at neuromuscular junctions, has become the first-line therapy for treating focal or segmental spasticity. Current clinical recommendations for muscle-specific dosing, sites of injection, dosage and dilution as well as the formulation of BTX and adjunct treatments to boost effects are based on the injector’s decision [3]
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