Critically Appraised Topic
The patient who led me to pursue this question is a 7-year-old male with a diagnosis of cerebral palsy (CP) with spastic diplegia and bilateral hip subluxation with acetabular dysplasia and bilateral equinus contractures. Medical treatment to date has included bilateral proximal femur varus derotation osteotomies with blade plate fixation, Dega pelvic acetabuloplasties, and bilateral botulinum toxin A (BTX-A) injections of the gastrocsoleus complex. Problems identified include bilateral hip and knee flexion contractures, bilateral lower extremity strength deficits, decreased bed mobility, decreased transfers, decreased bilateral lower extremity weight bearing tolerance, and decreased ambulation quality and endurance.
Do botulinum toxin A injections in conjunction with physical therapy treatment result in improved muscle spasticity and motor function compared to physical therapy treatment alone in children with CP?
Clinical Bottom Line
Due to the significant number of major threats to the internal validity of the Williams et al. study, including lack of a well-explained study design that necessitated many assumptions regarding data analysis, the data from this article will be excluded in this overall clinical bottom line. Based on the results of the outcomes from Scholtes et al., El-Etribi et al., and Reddihough et al. with a composite number of 135 subjects, BTX-A injections to select lower extremity muscles in conjunction with a PT program resulted in only modest statistically significant improvements in muscle spasticity and motor function compared to PT alone. The amount of PT hours the intervention groups received ranged from approximately 27.8 hours to approximately 60 hours. The general principles and concepts of the PT programs can readily be applied in the clinical setting. Of the three studies, the greatest improvement in muscle spasticity was 1.04 MAS points and the greatest improvement in ankle dorsiflexion passive ROM with knee flexion was 13.7˚. However, since there is no established MCID for the MAS in children with CP, it is not known whether this change in muscle spasticity was clinically important. The amount of change in ankle dorsiflexion ROM likely exceeds the MDC for a goniometric measurement, so it is reasonable to expect that some individuals experienced a real average increase in ankle dorsiflexion ROM, though whether this was clinically significant was not determined. Since the peak BTX-A effect is typically around 6 weeks post-injection1, the majority of the assessment time points (~64%) in all of these studies are likely beyond the timeframe of peak BTX-A effect. Another possible reason why these studies did not show better improvements is suboptimal selection of outcome measures, as muscle strength and muscle volume may not have best captured the effects of the BTX-A injections. Last, due to poor data presentation and discussion, major assumptions needed to be made regarding the assessment time points of the control group in the Reddihough et al. article, as well as timing of BTX-A injections in relation to initiation of the strength training program and total number of hours of strength training in the Williams et al. article. These assumptions significantly threatened the confidence in data interpretation and conclusions drawn from these studies. Only the Reddihough et al. study included outcome measures assessing functional improvements (via the GMFM) and parent satisfaction (via the parental questionnaire). For the other studies, it would have been helpful to know if the small improvements in muscle spasticity and ROM allowed the children and/or parents to more easily perform functional ADLs or IADLs. Future studies should include the use of outcome measures that capture participation level activities. Due to the many threats to the internal validity that significantly compromise methodological quality, the results from these studies should be not be extrapolated to a larger patient population.
Yamamoto, Stephanie, "The Effects of Botulinum Toxin Type-A on Spasticity and Motor Function in Children with Cerebral Palsy" (2014). PT Critically Appraised Topics. 57.