Altered bladder-related brain network in multiple sclerosis women with voiding dysfunction

Abstract

Objectives: A number of neurourology imaging studies have mainly focused on investigating the brain activations during micturition in healthy and neuropathic patients. It is, however, also necessary to study brain functional connectivity (FC) within bladder-related regions to understand the brain organization during the execution of bladder function. This study aims to identify the altered brain network associated with bladder function in multiple sclerosis (MS) women with voiding dysfunction through comparisons with healthy subjects via concurrent urodynamic study (UDS)/functional magnetic resonance imaging (fMRI).

Materials and methods: Ten healthy adult women and nine adult ambulatory women with clinically stable MS for ≥6 months and symptomatic voiding phase neurogenic lower urinary tract dysfunction (NLUTD) underwent UDS/fMRI evaluation with a task of bladder filling/emptying that was repeated three to five times. We quantitatively compared their FC within 17 bladder-related brain regions during two UDS phases: "strong desire to void" and "(attempt at) voiding initiation."

Results: At "strong desire to void," the healthy group showed significantly stronger FC in regions involved in bladder filling and suppression of voiding compared to the patient group. These regions included the bilateral anterior cingulate cortex, right supplementary motor area, and right middle frontal gyrus. During "(attempt at) voiding initiation," healthy subjects exhibited stronger FC in the right inferior frontal gyrus compared to MS patients.

Conclusion: Our study offers a new way to identify alterations in the neural mechanisms underlying NLUTD and provides potential targets for clinical interventions (such as cortical neuromodulation) aimed at restoring bladder functions in MS patients.

Keywords: brain connectivity; functional magnetic resonance imaging; micturition; multiple sclerosis; neurogenic bladder; urinary retention; urodynamic study; voiding dysfunction.

Figure 1

Concurrent UDS and MRI procedures

Figure 2

The list and location of regions of interest (ROIs)

Figure 3

Brain functional connectivity maps at ‘strong desire to void/full bladder capacity’ and ‘(attempt at) voiding initiation’ averaged across ten healthy women and nine MS women, respectively. The size of the spheres and the color bar represent correlation values ranging from 0 to 1.

Figure 4

A. Group average map of the functional connectivity difference between healthy and MS patients (healthy subjects minus MS patients) during ‘strong desire to void’. B. Average map of the functional connectivity within ten healthy women transitioning from ‘strong desire to void’ to ‘voiding initiation’. C. Average map of the functional connectivity within nine MS women transitioning from ‘strong desire to void’ to ‘(attempt at) voiding initiation’. The size of the spheres and the color bar represent correlation values ranging from −1 to 1. VI: voiding initiation; SDTV: strong desire to void.