The beneficial antispasticity effect of botulinum toxin type A is maintained after repeated treatment cycles

Abstract

Objective: To study the efficacy, safety, and incidence of BtxA antibody formation with repeated treatments with BtxA in post-stroke upper limb muscle spasticity. Methods: The study was a prospective open label trial. Patients with established post-stroke upper limb spasticity received 1000 units of BtxA (Dysport) into five muscles of the affected arm on study entry. Treatment was repeated every 12, 16, or 20 weeks as clinically indicated. Each patient received a total of three treatment cycles. Efficacy of treatment was assessed using the Modified Ashworth Scale. Patients were assessed on study entry and on week 4 and 12 of each treatment cycle for all safety and efficacy parameters. Blood samples for BtxA antibody assay were taken at baseline and on completion of the trial. Results: Fifty one patients were recruited and 41 of them completed the study. Improvement from the cycle one baseline was observed in all the outcome measures. Mild to moderately severe treatment related adverse events were reported in 24% of cases. There were no serious adverse events. No BtxA antibodies were detected. Conclusion: BtxA at a dose of 1000 units Dysport was efficacious in the symptomatic treatment of poststroke upper limb spasticity. The study suggests that this effect can be maintained with repeated injections for up to at least three treatment cycles, with duration of effect per cycle of between 12 and 20 weeks. BtxA was safe in the dose used in this study and did not induce the formation of detectable levels of neutralising BtxA antibodies.

Botulinum neurotoxins for post‐stroke spasticity in adults: A systematic review

“…10 Another open label trial mentioned that improvement in spasticity was maintained for three consecutive BoNT/A treatments at different intervals of 3, 4, or 5 months, as clinically indicated. 39 Adequate management of patients with post-stroke spasticity requires knowledge of long-term outcomes following repeated BoNT treatments--an aspect that remains to be addressed by specific studies.…”

BoTULS: a multicentre randomised controlled trial to evaluate the clinical effectiveness and cost-effectiveness of treating upper limb spasticity due to stroke with botulinum toxin type A

“…51 Six uncontrolled studies have examined the effects of repeated injections. [57][58][59][60][61][62] These studies are summarised in Appendix 1, Table 36. Repeat injections decreased muscle tone by a similar amount after each injection and improved passive functional scores by a similar amount to the initial injection.…”

“…Repeat injections decreased muscle tone by a similar amount after each injection and improved passive functional scores by a similar amount to the initial injection. [58][59][60]62 Two studies measured active function 58,61 and one found improvement.…”

Botulinum Toxin in Poststroke Spasticity

“…These results were consistent with a study that suggested sustained antispastic effects of BTX after repeated injections for up to at least three treatment cycles. 46 Other uncontrolled trials with similar results have reported spasticity reduction in the hemiparetic upper limb without significant functional improvement in global assessment measures. [47][48][49] Interestingly, an exploratory meta-analysis, including two randomized, controlled trials, has revealed that reduction in spasticity was associated with significant improvement in arm function.…”

“…One study evaluating antibody levels in patients with poststroke spastic upper extremity has reported that repeated treatment cycles of BTX-A were not associated with detectable levels of antibody and this result was partly attributed to a shorter treatment duration compared with the results of cervical dystonia studies. 28 Another drawback for BTX therapy is high cost and the transient nature of the toxin. Although pharmacoeconomic evaluations of the available spasticity treatment alternatives are limited, BTX has been found to be cost-effective in poststroke spasticity when compared with oral anti-spastic drugs.…”