Tibial Nerve Cryoneurolysis for Spastic Equinus and Equinovarus Foot.

Abstract

To quantify longitudinal electrophysiologic changes after cryoneurolysis in participants with spastic equinus and equinovarus foot (SEF). 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. 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). Cryoneurolysis elicited long-lasting electrophysiologic changes and clinical improvements indicating decreased spasticity severity.