Analgesia by Cryotherapy in Patients with Chronic Pain with Analysis of Pain-Modulating and Pro-Inflammatory...

Background/Objectives: Whole-body cryotherapy (WBC) is increasingly utilized as a physical modality for managing chronic pain, although its mechanism of action remains incompletely understood. This study evaluated whether WBC influences serum levels of substance P, calprotectin, β-nerve growth factor (β-NGF), and calcitonin gene-related peptide (CGRP), which are implicated in pain modulation. Methods: Serum samples from 61 participants-37 undergoing WBC and 24 not receiving WBC-were collected at the start and end of a multimodal inpatient pain treatment program. Pain intensity was assessed using a numerical rating scale (NRS). Biomarker concentrations were measured by enzyme-linked immunosorbent assay (ELISA). Results: Both groups reported an average significant pain reduction of more than 1.39 points on the NRS. Of the biomarkers analyzed, only calprotectin showed a statistically significant reduction in the overall cohort (p = 0.007) and in the WBC subgroup (p = 0.032). Among patients who did not experience significant pain reduction, those in the WBC group exhibited a greater decline in calprotectin compared to controls (p = 0.042), especially among those without medication changes (p = 0.016). No significant differences were detected for the other serum parameters. Conclusions: The analgesic effects of WBC could not be attributed to changes in the neuromodulatory peptides measured. However, the significant reduction in calprotectin suggests a potential anti-inflammatory effect of WBC on the innate immune response.