Ultrasound-Guided Percutaneous Cryoneurolysis for Refractory Lower-Limb Spasticity in Upper Motor Neuron Disorders: A...

To evaluate the safety, technical feasibility, and short- to medium-term clinical effectiveness of ultrasound-guided percutaneous cryoneurolysis in patients with refractory lower-limb spasticity secondary to upper motor neuron (UMN) disorders.

This single-centre retrospective case series included consecutive patients with chronic, severe lower-limb spasticity [Modified Ashworth Scale (MAS) ≥ 3] refractory to oral antispasmodics and/or botulinum toxin injection, all of whom had prior positive diagnostic perineural blocks. Cryoneurolysis was performed under real-time ultrasound guidance using a cryoprobe cooled to a nominal probe-tip set-point of - 90 °C, with a standardised 5-min freeze/5-min thaw/5-min freeze protocol. Perineural dexamethasone (4 mg) was administered at the end of each procedure. Outcomes were assessed at baseline, 3 months, and 9 months and included the MAS, a 0-10 Visual Analogue Scale (VAS) for pain, joint range of motion, and clinician-rated functional performance. Technical success was defined a priori as accurate sonographic nerve targeting with concordant motor response. Clinical success was defined as a ≥ 1-point reduction in MAS with concurrent functional improvement.

Four patients (three men, one woman; median age 27 years, range 25-30; spinal cord injury n = 2, cerebral palsy n = 1, traumatic brain injury n = 1) underwent ten nerve-level cryoneurolysis interventions. Technical success was achieved in all procedures (10/10; 100%). Clinical success was observed in 3/4 patients (75%) and in 7/10 treated nerves (70%) at 3 months and was sustained or further improved at 9 months in all responders, with no need for re-treatment during the 3-9-month interval. Median limb-level MAS decreased from 3.3 (range 2.0-4.0) at baseline to 2.3 (range 1.0-3.5) at 3 months and to 1.5 (range 0.5-3.5) at 9 months. Two patients (P1 and P3) reported progressive pain reduction (VAS decrease of approximately 10-50% at 3 months and 35-70% at 9 months). Functional gains observed at 3 months-including improved transfers, sitting balance, mobility, and independence in activities of daily living-were sustained at 9 months. One patient did not improve at either time point; cross-sectional imaging subsequently demonstrated fixed contracture and muscle atrophy. No procedure-related complications were recorded through 9 months of follow-up.

Ultrasound-guided percutaneous cryoneurolysis was technically feasible and safe, and produced clinically meaningful short- and medium-term reductions in spasticity with associated functional gains that were sustained at 9 months in all responders without re-treatment. The technique warrants prospective, adequately powered evaluation, ideally incorporating validated patient-reported outcomes and longer follow-up.

Level 4, retrospective case series.