Adverse events associated with botulinum toxin A injection in the treatment of the upper and lower limbs muscles spasticity and dystonia: a systematic review with meta-analysis

Neuromuscular block with the injection of botulinum toxin type A is one of the treatment of spastic hypertonia or dystonia. To date, this treatment is considered safe, severe adverse events are described in few cases, most of harms are minor and tolerable. In previous published reviews, authors analysed only partially the most frequent aspects related to the usual clinical setting in which our group operate (e.g. works which did not consider all the botulinum toxin type A formulations, or limited to restricted anatomical districts, or focused just on post-stroke spasticity). Specifically, the aim of this review is to add further information to the actual knowledge by searching for studies which considered all the botulinum toxin type A formulations in the management of limbs’ muscles spasticity or dystonia as positive features of upper motor neuron syndrome. At this point, to better quantify the safety and adverse events related to neuromuscular block with botulinum toxin, we consider important that the comparison should be made with placebo or other treatment. This work could represent a useful informative instrument for clinicians and patients about the safety of this therapy and any eventual peri-procedural complication.