Muscle physiology and the science of tone agents

Cerebral Palsy (CP) encompasses a spectrum of permanent motor disorders stemming from early insults to the developing brain, resulting in alterations in muscle tone. While spasticity and dystonia are common motor disorders in CP, non-neural factors such as changes in muscle architecture contribute to muscle stiffness. Muscle stiffness in CP involves changes in muscle morphology and structure. Current treatments, such as botulinum toxin, have limitations, leading to exploration of alternative techniques like cryoneurolysis, hyaluronidase, and extracorporeal shockwave therapy. This brief review advocates for a comprehensive approach that considers both muscular and neurologic components of hypertonia, emphasizing the need for further research on cellular-level changes contributing to muscle stiffness. IMPACT: This review highlights the gap in current literature regarding the complex interplay between neural and non-neural factors in muscle stiffness and hypertonia in children with cerebral palsy (CP). While spasticity and dystonia are well studied, the review emphasizes the need for interventions addressing muscle morphology and extracellular matrix stiffness. It introduces emerging therapies like cryoneurolysis, hyaluronidase, and extracorporeal shockwave therapy, calling for more research on their long-term efficacy and safety.