Login to Access Video or Poster Abstract: MP29-02
Sources of Funding: none

Introduction

The mechanism of action of cyclosporine (CyA) to treat bladder pain syndrome/interstitial cystitis (BPS/IC) has not been clearly elucidated. It is thought that CyA may act directly on pain sensing nerves. Therefore, we sought to determine CyA effect on various nerve fibers by measuring current perception (CPT) and pain tolerance thresholds (PTT) using the neurometer at baseline and after treatment with CyA. Additionally, we sought to compare responders versus non responders, as well as those with and without Hunner&[prime]s ulcers.

Methods

A total of 26 patients were enrolled in this NIH funded study. CPT and PTT were obtained at the index finger and suprapubic site. Neurometer measurements were taken at 5 Hz (unmyelinated C), 250 Hz (myelinated A-delta), and 2000 Hz (myelinated A-beta fibers). Specifically, C fibers sense a broad range of painful stimuli. Descriptive results were presented as means with standard deviations and medians with interquartile range (IQR) for continuous variables. Comparison between groups was made using paired Wilcoxon rank sum test for continuous variables with a p value of 0.05 considered significant. All analyses were done using the statistical software package R (version 3.3.0).

Results

Of the 26 patients, 14 were women, 7 patients had pretreatment Hunner&[prime]s ulcers, and 11 patients were considered responders (improvement in Global Response Assessment or >30% improvement in IC Symptom Index). When comparing all patients at baseline to 3-months, there was a significant decrease in PTT at 5 Hz (median of 375 vs. 250, p=0.05), meaning pain tolerance decreased during treatment with cyclosporine. However, one month after cyclosporine treatment was completed, there was no difference from baseline (median of 375 vs. 325, p=0.27). When responders only were evaluated, there was a significant decrease in PTT at 5 Hz from baseline to 3 months (median 450 vs. 262.5, p=0.037) as well from baseline to 4 months (median 450 vs. 275, p=0.015). There was no difference of CPT and PTT measurements in responders compared to non-responders or in those with or without Hunner&[prime]s ulcers.

Conclusions

While not predictive of response to CyA or baseline phenotype, a change in PTT was seen in those who responded to treatment. As pain tolerance threshold decreased in patients successfully treated with CyA, the mechanism of action and effect of CyA may be beyond its immunosuppressant effect.

Funding

none