Combining strength training and botulinum neurotoxin intervention in children with cerebral palsy: the impact on muscle morphology and strength

Abstract

Purpose: Investigate the combination effects of strength training and Botulinum Toxin Type-A (BoNT-A) on muscle strength and morphology in children with Cerebral Palsy (CP). Methods: Fifteen children receiving BoNT-A, classified as Spastic Diplegic CP, GMFCS I-II, and aged 5–12 years were recruited for this study. Randomly allocated to 10 weeks of strength training either before or after BoNT-A, children were assessed over 6 months. Eight of the 15 children also completed a control period. The Modified Ashworth Scale measured spasticity. The Goal Attainment Scale (GAS) assessed achievement of functional goals. Magnetic Resonance Imaging assessed muscle volume (MV). Instrumented dynamometry assessed strength. Results: Spasticity was significantly reduced following BoNT-A injection (p = 0.033). Children made significant isokinetic strength gains (mean p = 0.022, ES = 0.57) in the intervention period compared to the control period (mean p = 0.15, ES = 0.56). Irrespective of timing, significant strength improvements were seen immediately (10 weeks) and over 6 months for all children. This was also the case for improvements in the GAS (immediately: mean p = 0.007, ES = 4.17, 6 months: mean p = 0.029, ES = 0.99), and improvements in MV in all assessed muscles. Conclusion: The simultaneous use of BoNT-A and strength training was successful in spasticity reduction, improving strength and achieving functional goals, over and above treatment with BoNT-A alone. Muscles targeted for BoNT-A injection should be included in strength training.

Implications for Rehabilitation

Cerebral Palsy

• Botulinum toxin type-A (BoNT-A) and strength training are available interventions that, on their own have found success in managing spasticity and muscle weakness (both significant motor impairments), respectively in children with Cerebral Palsy (CP).

• This study has demonstrated that the concurrent treatment of BoNT-A and strength training can achieve positive outcomes in terms of strength, spasticity and for the achievement of set functional goals.

• The results of this study show that the improved muscle strength can be associated with hypertrophy, which could indicate the potential role of strength training in altering the rate of muscle growth, in an aim to improve the failure of muscle growth associated with CP.

• Home based strength training, based on a child’s individual goals is shown to be successful in improving strength and goal attainment for children with CP.

Keywords::

• Botulinum neurotoxin
• cerebral palsy
• children
• muscle weakness
• muscle volume
• spasticity

Acknowledgements

The authors would like to thank the Department of Paediatric Rehabilitation, PMH for their support and assistance with recruitment, the Department of Diagnostic Imaging, PMH for their assistance and knowledge in data collection and the contribution of the School of Sport Science, Exercise & Health at UWA for the use of equipment and facilities. Sincere thanks to Tania Shillington, Bree Dwyer and Martin Spits for their role with data collection, Nadine Williams for her input, and the children and families who volunteered to participate in this study.

Declaration of Interest: This project was supported by Princess Margaret Hospital (PMH) Foundation Grant as well as by the University of Western Australia’s (UWA) Research and Development Awards. The first draft was written by the first author, Sian Williams, and there was no form of payment given to her or any of the authors for the production of this paper. The authors report no conflicts of interest in this study.