Objective: 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.
Results: 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.
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