Employment of higher doses of botulinum toxin type A to reduce spasticity after stroke

Spasticity is a common disabling symptom for several neurological conditions. Botulinum toxin type A injection represents the gold standard treatment for focal spasticity with efficacy, reversibility, and low prevalence of complications. Current guidelines suggest a dose up to 600 units (U) of onabotulinumtoxinA/incobotulinumtoxinA or up to 1500 U of abobotulinumtoxinA to treat post-stroke spasticity to avoid important adverse effects. However, recently, higher doses of botulinum toxin type A were employed, especially in case of upper and lower limb severe spasticity. With searches of US National Library of Medicine databases, we identified all studies published from December 1989 to July 2014 concerning the use of higher doses of this neurotoxin for spasticity treatment with at least a dose of 600 U of onabotulinumtoxinA and incobotulinumtoxinA or 1800 U of abobotulinumtoxinA. The cumulative body of evidence coming from the eight studies selected suggested that higher doses of botulinum toxin type A appeared to be efficacious in reducing spasticity of the upper and lower limbs after stroke, with adverse effects generally mild. However, further investigations are needed to determine the safety and reproducibility in larger case series or randomized clinical trials of higher doses of botulinum toxin type A also after repeated injections.