Comparative Neuroexcitation Patterns Using fNIRS in Women With Overactive Bladder

Functional near-infrared spectroscopy (fNIRS) is a noninvasive technique used to quantify prefrontal cortex (PFC) neuroexcitation. The PFC is involved in the decision to void, and dysfunction in the region has been associated with overactive bladder (OAB). This study demonstrates neuroexcitation differences in the brain region associated with the decision to void (prefrontal cortex) using noninvasive fNIRS.

The objective of this study was to compare PFC neuroexcitation during natural filling in female participants with and without OAB.

Female participants with OAB were cross-sectionally compared with controls without urinary urgency. The fNIRS signals were continuously recorded during an oral hydration protocol. Simultaneously, recordings of real-time bladder sensation of fullness were completed. A period of "high sensation" was defined as the time from first desire to 100% sensation. Signal analysis included removal of motion artifact, low pass filtering, and interpolated to standardize reporting bladder filling time.

A total of 25 female participants were enrolled and had complete analyzable data, including 14 with OAB and 11 controls without OAB. Change in O2Hb during the high sensation period was significantly lower in all PFC regions in the OAB group compared with controls (P < 0.001). The majority of OAB participants had a constant or decreasing neuroexcitation pattern, which differenced in comparison to normal controls who displayed an increasing pattern.

This study demonstrates that fNIRS PFC excitation during a period of high sensation is consistently lower in women with OAB as compared with controls. These data support the hypothesis that the PFC plays an inhibitory role in voiding function and that there may be a lack of inhibitory control in women with OAB.