Posterior Single-Window Ultrasound-Guided Cryoneurolysis for Severe Pediatric Spastic Equinovarus: Technical Feasibility and Same-Patient Comparison

Background and Clinical Significance: Severe pediatric spastic equinovarus may significantly impair positioning, orthotic tolerance, hygiene management, caregiver-assisted mobilization, and assisted standing activities. In children with severe cerebral palsy, clinically meaningful outcomes frequently include reduction in caregiver burden and facilitation of daily care rather than restoration of autonomous gait. Ultrasound-guided cryoneurolysis has recently emerged as a minimally invasive option for focal spasticity management, although procedural workflow and tolerability remain challenging in severe deforming patterns. Case Presentation: We report a CARE-compliant same-patient bilateral technical comparison in a 9-year-old child with severe spastic cerebral palsy and bilateral dynamic equinovarus refractory to intensive rehabilitation and repeated botulinum toxin treatment. Baseline severity was consistent with GMFCS level IV. One lower limb was treated using the proposed posterior single-window ultrasound-guided cryoneurolysis approach through a single posterior proximal-calf window, whereas the contralateral limb underwent a conventional multi-point supine strategy. The posterior single-window approach enabled sequential targeting of multiple motor branches through a single posterior access corridor under continuous ultrasound guidance. The procedure required approximately 1 mL of 2% lidocaine without additional sedation and was completed in approximately 4 min, whereas the conventional supine strategy required multiple access points, repeated probe repositioning, minimal conscious sedation with midazolam, and approximately 20 min. At follow-up, lower-limb spasticity improved from approximately MAS 3 toward MAS 2, passive ankle angle, measured as the tibia–foot angle with 90° corresponding to the neutral ankle position, improved from approximately 80° to 95°, and semitendinosus-related hypertonia was reduced. Clinically meaningful improvement in positioning, hygiene management, assisted standing, and rehabilitation handling was observed. Caregiver-reported satisfaction and procedural tolerability were qualitatively perceived as better with the posterior single-window approach. Conclusions: The proposed posterior single-window cryoneurolysis strategy may represent a technically simplifying and clinically relevant minimally invasive approach for severe pediatric spastic equinovarus. Further prospective studies are required to confirm reproducibility, safety, and long-term outcomes.