**2. Intravesical treatment**

### **2.1 Dimethyl sulfoxide**

Intravesical instillation of dimethyl sulfoxide (DMSO) was approved by the FDA in 1978 as a treatment method for IC/BPS. The mechanism of action of DMSO may involve anti-inflammatory effects, nerve blockade, smooth muscle relaxation, and collagen inhibition [6]. In the American Urological Association (AUA) guidelines, intravesical DMSO may be used for symptoms refractory to conservative measures or as initial treatment to address severe symptoms as second-line treatment [7]. In contrast, the EAU guideline does not recommend the use of DMSO because of insufficient evidence. A review by Cochrane also reported that the evidence for treating IC/BPS with intravesical DMSO is limited [6]. In 1988, Perez-Marrero et al. [8] published a trial with 33 patients and found that the proportion of patients with subjective symptom improvement was 53% among DMSO-injected patients compared with 18% in the placebo group. Since then, several single-arm studies have been reported, and most studies have confirmed the 61–95% of therapeutic effect of DMSO in patients who did not respond to medication or hydrodistension.

A multicenter, randomized, placebo-controlled trial examining DMSO compared with placebo in 96 patients was recently published in Japan in 2021 [9]. The mean O'Leary-Sant Interstitial Cystitis Symptom Index (ICSI) score at week 12 decreased by −5.2 in the DMSO group compared with a decrease by −3.4 in the placebo group, with a statistically significant difference between the groups. Although the O'Leary-Sant Interstitial Cystitis Problem Index (ICPI), number of frequency,

*Management of Hunner Lesion in Interstitial Cystitis/Bladder Pain Syndrome Patients DOI: http://dx.doi.org/10.5772/intechopen.100052*

mean voided volume, and maximum voided volume showed significant improvement in the DMSO group compared with placebo group, there was no significant difference in the pain score between the two groups at 12 weeks. In this study, Hunner lesions were confirmed by cystoscopy at baseline in 86% of all patients. The authors speculated that the high incidence of Hunner lesions may have contributed to the clinical efficacy of DMSO. Although it was a small study, another study compared the efficacy of DMSO treatment between patients with and without Hunner lesion, and DMSO intravesical instillation showed a significant therapeutic effect only in IC/BPS patients with Hunner lesion. These findings suggest that IC/ BPS with Hunner lesion and IC/BPS without Hunner lesion have different characteristics, and intravesical DMSO treatment with strong anti-inflammatory effects may play a greater role in Hunner lesion type IC/BPS.
