Tibial Nerve Cryoneurolysis for Spastic Equinus and Equinovarus Foot

OBJECTIVE: To quantify longitudinal electrophysiologic changes after cryoneurolysis in participants with spastic equinus and equinovarus foot (SEF). DESIGN: In this prospective, observational cohort study (NCT049072010), 44 adults with SEF due to upper motor neuron disorder for ≥6 months and a positive response to diagnostic nerve block were enrolled (February 2021-October 2022; 40 completed 1-year follow-up) and received cryoneurolysis of the tibial nerve trunk or selected tibial motor nerve branches to individual muscles. Hoffmann reflex (H-reflex) amplitude and latency, H-reflex amplitude/motor response (M-wave) amplitude (H/M) ratio, spasticity severity, catch angle with fast movement (V3), and maximum passive range of motion (V1) for ankle dorsiflexion were assessed. RESULTS: From baseline to 1 year, H-reflex amplitude changed significantly (95% confidence interval [CI], -3.11, -0.44; P =0.01), H/M ratio significantly decreased (95% CI, -0.38, -0.14; P <0.001), mean V1 for ankle dorsiflexion increased with knee extension (-9.7° vs. 1.8°; P <0.001) and flexion (-1.8° vs. 8.6°; P <0.001), mean V3 improved during knee extension (-20.0° vs -11.7°; P =0.01), and median Modified Ashworth Scale score for ankle dorsiflexion decreased significantly during knee extension (4 vs. 2; P <0.001) and flexion (3 vs. 2; P <0.001). CONCLUSION: Cryoneurolysis elicited long-lasting electrophysiologic changes and clinical improvements indicating decreased spasticity severity.