Several muscle properties seemed to deviate from reported norms, although age- and muscle-specific references are sparse. Prospective studies are necessary to distinguish cause and effect and to refine the risks and benefits of these treatment options.

Spasticity in children with cerebral palsy can be managed by a spectrum of approaches, from conservative therapy, to temporary botulinum toxin A injections, to permanent transection of sensory nerves with a selective dorsal rhizotomy. This pilot study investigated whether these three tone management approaches are associated with histological and biochemical properties of the medial gastrocnemius. Design: A convenience sample of children with cerebral palsy undergoing gastrocnemius lengthening surgery was enrolled. Intraoperative biopsies were obtained from three individuals (one each: minimal tone treatment; frequent gastrocnemius botulinum toxin A injections; previous selective dorsal rhizotomy). All individuals had plantarflexor contractures, weakness, and impaired motor control before the biopsy.

Differences between participants were observed for muscle fiber cross-sectional area, fiber type, lipid content, satellite cell density, and centrally located nuclei. The most pronounced difference was the abundance of centrally located nuclei in the botulinum toxin A participants (52%) compared with the others (3-5%). Capillary density, collagen area and content, and muscle protein content were similar across participants. Conclusions: Several muscle properties seemed to deviate from reported norms, although age- and muscle-specific references are sparse. Prospective studies are necessary to distinguish cause and effect and to refine the risks and benefits of these treatment options.