Comparisons of immediate efficacy of cryoneurolysis and phenol neurolysis in spasticity reduction using Modified Ashworth Scale after brain injury: A retrospective cohort study

BACKGROUND: Phenol neurolysis and cryoneurolysis are nerve block procedures used to manage localized spasticity through different mechanisms, chemical and cold-induced nerve blocks, respectively. Both procedures can cause immediate reduction in spasticity. OBJECTIVE: To compare the immediate efficacy of cryoneurolysis versus phenol neurolysis in reducing spasticity severity as measured by the Modified Ashworth Scale (MAS) in patients with brain injury-related spasticity across multiple muscle groups. DESIGN: A retrospective chart review. SETTING: A free-standing rehabilitation hospital. PARTICIPANTS: Thirty-five patients who received either cryoneurolysis or phenol neurolysis. Twenty-two patients received phenol neurolysis (mean age 36.0 ± 14.8 years) with a total of 82 nerve blocks and 13 underwent cryoneurolysis (mean age 47.8 ± 19.8 years) with a total of 35 nerve blocks. MAIN OUTCOME MEASUREMENTS: Spasticity assessment using the MAS was performed before and immediately after each treatment session. RESULTS: Both cryoneurolysis and phenol neurolysis resulted in a significant immediate reduction in spasticity. For cryoneurolysis, MAS scores improved from 3.7 ± 0.7 to 1.1 ± 0.6 (p < .01), and for phenol neurolysis, from 3.8 ± 0.6 to 1.2 ± 0.5 (p < .01). However, there was no statistically significant difference in MAS reduction between the two treatment modalities. Additionally, no significant differences were observed between groups in MAS reduction across specific muscle groups in both upper and lower limbs. CONCLUSIONS: Cryoneurolysis and phenol neurolysis both produced significant immediate reductions in spasticity as measured by the MAS in patients with brain injury. Cryoneurolysis and phenol neurolysis demonstrated comparable effectiveness for acute spasticity management in a rehabilitation setting. Future prospective studies should assess longer-term outcomes, tolerability profiles, and cost-effectiveness to guide optimal technique selection.