To explore alterations in the brain function of patients with interstitial cystitis /bladder pain syndrome (IC/BPS) during the resting state.

This study prospectively recruited 7 patients with IC/BPS who were admitted to the Urology Department of Beijing Hospital from December 2023 to May 2024 as the experimental group, and concurrently selected 12 healthy individuals as the control group. After enrollment, each subject underwent an rs-fMRI scan. General clinical data such as age and gender, as well as data from the ICSI, ICPI, VAS, SAS, and SDS questionnaires were collected. The data were processed with Matlab. The present study employed a paired sample t-test to analyze the discrepancies in gray matter volume among the two groups of subjects. The brain functional activities of the subjects were analyzed by regional homogeneity (ReHo) and low-frequency amplitude (ALFF) algorithms. Grounded on the acquired abnormal brain regions, further functional connectivity (FC) analysis was carried out to explore the connectivity patterns among the functional brain regions.

No significant differences were observed in age (T = -0.68, P = 0.536) or gender (c2 = 0.019, P = 0.891) between the experimental group and the control group. The scores of SAS and SDS in the experimental group were significantly higher than those in the control group (P < 0.001). After undergoing dual GRF correction analysis at both the voxel and cluster levels, no significant difference was found in the volume of whole-brain gray matter (P > 0.01). In contrast to the control group, the ALFF value of the left superior parietal lobe (MNI: x, y, z= -21, -66, 60；T=12.5305) was elevated in IC/BPS patients, and the ReHo value of the left precuneus (MNI: x, y, z= -9, -54, 63；T=9.4103) was also increased. Through FC analysis, it was revealed that IC/BPS patients exhibited significantly lower FC values between the left superior parietal lobule and the central sulcus (MNI: x, y, z=21, 15, 3; T=-27.8356 ) , as well as between the left anterior cingulate and the left posterior cingulate gyrus (MNI: x, y, z= -12, 0, 42; T=-8.7389 ) in comparison with the control group.

In contrast to normal individuals, IC/BPS patients demonstrate functional aberrations in the left superior parietal lobule and the left precuneus. Moreover, a decrease in functional connectivity is observed between the left superior parietal lobule and the central sulcus, as well as between the left precuneus and the left posterior cingulate gyrus. These abnormal functional alterations in the brain might be implicated in the maintenance and development of symptoms in IC/BPS patients. This study carried out research from the perspective of central nervous system regulation, presenting possible directions for further exploration of the pathophysiological mechanisms of IC/BPS.