Differential Impacts of Selective Dorsal Rhizotomy and Botulinum Toxin on Muscle Physiology in Cerebral Palsy
Cerebral palsy (CP) is a motor disorder caused by an upper motor lesion characterized by skeletal muscle weakness, tone, spasticity, and contractures, as well as poor motor control, posture, and balance. Tone control treatments target motor or sensory nerves (botulinum toxin, BoNTS or selective dorsal rhizotomy, SDR), respectively, but structural and functional differences between approaches are not well explored. Information on the impact on skeletal muscle function and quality could provide meaningful clinical information. Intraoperative-acquired biopsied medial gastrocnemius muscle from CP patients treated with SDR, repeated BoNTS, or no tone management were analyzed for nuclei, collagen abundance, fiber type, cross-sectional area, intramuscular lipid abundance, satellite cells, and capillarity, as well as biochemical abundance of collagen isoforms and total protein. Briefly, only the BoNTS participant’s muscle had an abundance of centrally located nuclei (52% of fibers), indicative of cycles of muscle degeneration and regeneration, and greater capillarity per fiber (1.26 vs. 0.21 SDR, 0.44 no tone). Contrastingly, the BoNTS participant’s myofibers had a lower intramuscular lipid content than participants with SDR or no tone. These data suggest current treatments for CP were associated with divergent histological and biochemical properties that should be considered when making clinical decisions regarding treatment.