Long-term effects of botulinum toxin A in a cerebral palsy cohort

Abstract

In a prospective cohort study we investigated the long-term effects of BTX-A treatment in children with CP, mainly if the effect on muscle tone and joint range of motion (ROM) remain after repeated injections over several years. 94 children with CP receiving BTX-A to the lower extremities were followed for a median of 562 days. The longest follow-up time was 3.6 yr and included a maximum of 8 inj./muscle. 50% of the patients had spastic diplegic, 22% hemiplegic, 25% tetraplegic and 3% dyskinetic CP. The GMFCS level was I in 29%, II in 15%, III in 16%, IV in 17% and V in 23% of the patients. Median age at first injection was 5 yr 4mo. Adductor, Hamstring and Gastrosoleus muscles were given 785 BTX-A injections. Outcome measurements were muscle tone (Modified Ashworth scale) and ROM. Assessments were made before every injection, 3–6 weeks after and then at 90-day intervals. Also, the effect before and after repeated injections to M gastrocnemius were analyzed. Non-parametric statistics were used to identify significant changes as compared to baseline. BTX-A injections induced long-term tone reduction in all muscle groups—most apparent in the gastrocnemius was that each repeated injection produced an immediate decrease. Improvement in ROM was only briefly-measured after the first injections, whereupon the ROM declined. Conclusion BTX-A can be effective in reducing muscle tone over a longer period, but not in preventing development of contractures in spastic muscles.