Medial gastrocnemius muscle properties of children with cerebral palsy after different tone treatments - a pilot study.

OBJECTIVE: Spasticity in children with cerebral palsy (CP) can be managed by a spectrum of approaches, from conservative therapy to temporary botulinum toxin A (BoNT-A) injections, to permanent transection of sensory nerves with a selective dorsal rhizotomy (SDR). 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 CP undergoing gastrocnemius lengthening surgery were enrolled. Intraoperative biopsies were obtained from three individuals (1 each: minimal tone treatment; frequent gastrocnemius BoNT-A injections; prior SDR). All individuals had plantarflexor contractures, weakness, and impaired motor control prior to 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 BoNT-A participant (52%) compared to the others (3-5%). Capillary density, collagen area and content, and muscle protein content were similar across participants.

CONCLUSIONS: Several muscle properties appeared to deviate from reported norms, though 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.