Muscle-Tendon Unit In Children with Cerebral Palsy
A child’s ability to walk, run and play can depend a lot on their muscle’s ability to work well enough to propel their body and oppose gravity. In cerebral palsy (CP) muscles are often shortened so much that they restrict joint range of motion and the muscles themselves are weak. Thus, ‘shortness’ and ‘weakness’ are two important needs that clinicians must address. To address shortness, the tendons of muscles are often lengthened surgically so that the joint can regain its normal range of motion. This can dramatically improve walking and other types of movement although it really doesn’t change the muscle. Additionally, it is often possible to paralyze muscles using injected toxins so that their overactivity does not restrict movement.
Our ability to fix weak muscles has been a bit more difficult. Because of the injury to the brain, the muscles themselves do not respond to exercise the way muscles do of typically developing children. Normally, the mechanical effects of force on muscle cause activation of stem cells that live in the muscle and these stem cells divide and develop into new muscle tissue, causing growth. In CP, for reasons we don’t yet know, there are much fewer stem cells (about 80% less) compared to typical development and the stem cells that remain divide a lot but do not develop into muscle very well. Importantly, the problem with the stem cells can be fixed, at least in a glass dish, using an already-approved drug that has been used to treat other diseases. Our future studies will attempt to ‘repurpose’ this and other drugs to decrease the amount of time and money required to offer our patients solutions to ‘short’ and ‘weak’ muscles. We hope that this will lead to treatments that don’t always require surgery.
Lieber, R.L. and Theologis, T. (2021), Muscle-tendon unit in children with cerebral palsy. Dev Med Child Neurol, 63: 908-913. https://doi.org/10.1111/dmcn.14807