Quantification of cerebral blood flow during bladder filling in healthy subjects
Urine storage is a complex physiologic process that is under central nervous system control. It is unclear how brain activity changes as bladder volume and bladder sensations change. In this study, we quantify cerebral perfusion and the change in brain activity in healthy subjects during bladder filling.
We performed a prospective study of 8 women without bladder pathology. Participants were asked to undergo an fMRI exam while their bladders were filled via a catheter at a rate of 50ml/minute. Images were obtained at bladder volumes of 0, 50, 100, 200, 350, and 500mL. Subjects were instructed to indicate when they experienced the first sensation of bladder filling, first desire to void, and strong desire to void. For this exam, we used arterial spin labeling fMRI, which quantifies cerebral blood flow (CBF), which serves as a proxy for brain activity.
On average, participants experienced first and strong desire to void after 112 and 284mL filling, respectively. During bladder filling, there was a steady increase in CBF followed by a steep decrease in CBF (Table 1). The insula exhibited significantly increased perfusion at first desire to void compared to baseline (Figure 1,2), while the sensorimotor cortex exhibited decreased perfusion for the same comparison.
Our study results suggest that suppression of the desire to void results in deactivation of the regions that are initially activated by initial desire to void.
Funding: SUFU Neuromodulation grant