Are White Matter Tract Integrities Different in Multiple Sclerosis Women With Voiding Dysfunction?

Abstract

Objectives: Two white matter tracts (WMTs) are proposed to be involved in bladder function: anterior thalamic radiation and superior longitudinal fasciculus. Multiple sclerosis (MS) patients with voiding dysfunction (VD) may have distinct changes in these 2 WMTs. This study aims to compare the fractional anisotropy (FA) and mean diffusivity (MD) from diffusion tensor imaging of MS females with and without VD versus healthy controls (HCs).

Methods: Prospective observational cohorts of 28 female MS patients and 11 HCs were recruited. Multiple sclerosis patients were divided into 2 groups: voiders (patients without VD, n = 14) and VD (patients with VD, n = 14). Diffusion tensor imaging of each subject was obtained, from which FA and MD maps were generated. The mean FA and MD of each WMT on both sides were analyzed using one-way analysis of variance and pairwise comparison with adjusted P values.

Results: Overall MS patients had significantly lower mean FA (loss of coherence) and significantly higher mean MD (increased free diffusion) than HCs in both WMTs, indicating more damage. Furthermore, VD showed a trend of loss of integrity in both WMTs when compared with voiders with lower FA and higher MD.

Conclusions: There is damage reflected by lower FA and higher MD values in the proposed WMTs involved in bladder function in MS women. Voiding dysfunction in this patient population can be attributed to these damages considering women with VD demonstrated a trend of deterioration in these WMTs compared with women without VD. Future studies with larger sample sizes should be done to further confirm this correlation.

Conflict of interest statement

The authors have declared they have no conflicts of interest.

Copyright © 2020 American Urogynecologic Society. All rights reserved.

Figures

FIGURE 1.

Anatomy of the WMTs of interest (demonstrated on subject 18). A, axial and B, Sagittal ATR views. Axial (C) and sagittal (D) SLF views. Colors indicate direction of fiber tracts (red = transverse, blue = craniocaudal, green = anterior posterior).

FIGURE 2.

Fractional anisotropy value comparison of the left ATR, right ATR, left SLF, and right SLF among voiders, VD, all MS patients, and HC groups. Pairwise comparisons with an adjusted P value using the Benjamini-Hochberg method (α = 0.05) were performed on voiders, VD, and HC groups, and 2-sample t tests (α = 0.05) were performed on all MS and HC groups. Bars indicate standard deviation, and asterisks indicate significant difference between groups (P < 0.05). Fractional anisotropy values of all tracts in VD group were lower than those in voiders group.

FIGURE 3.

Mean diffusivity value comparison of the left ATR, right ATR, left SLF, and right SLF among voiders, VD, all MS patients, and HC groups. Pairwise comparisons with an adjusted P value using the Benjamini-Hochberg method (α = 0.05) were performed on voiders, VD, and HC groups, and 2-sample t tests (α = 0.05) were performed on all MS and HC groups. Bars indicate standard deviation, and asterisks indicate significant difference between groups (P < 0.05). Mean diffusivity values of all tracts in VD group were higher than those in voiders group. Voiding dysfunction versus voiders also showed significant difference approaching significant difference (P = 0.054) in the left ATR.