Multiple Sclerosis (MS) is an autoimmune inflammatory disease affecting white matter tracts and can lead to bladder storage and/or voiding dysfunction (VD). VD refers to abnormally slow and/or incomplete micturition, based on uncharacteristically slow urine flow rates and/or excessive post-void residuals (PVR). However, the absolute values of PVR of urine are unreliable metrics in the setting of MS where bladder capacity (BC) and compliance can also be decreased. The Expanded Disability Status Scale (EDSS) allows for quantification of disability in MS and for monitoring the changes in severity of disability over time; it is the most widely accepted measure for tracking disability progression in MS patients. We hypothesize that % post-void residuals/bladder capacity (%PVR/BC) correlates strongly with both EDSS and changes in white matter integrity as seen on Diffusion Tensor Images (DTI).

Ten adult women (>18 years of age) with clinically stable MS for ≥3 months and VD defined as %PVR/BC > 40% or Liverpool nomogram percentile less than the 10th percentile were recruited from our tertiary Neuro-urology Clinic. Patients participated in a clinical Urodynamic Study (UDS) and completed several questionnaires (i.e. Urogenital Distress Inventory (UDI-6), NBSS, AUASS). DTI images were acquired using a 7-Tesla Siemens MAGNETOM Terra MRI scanner (Matrix = 158 x 158, slick thickness 1.4 mm, Field-of-View (FOV) = 220 X 220 cm2, 64 directions, b-value = 1000 s/mm2, with a total scan time of 12 minutes and 14 seconds). DTI maps were constructed, and individual patients were co-registered with the ICBM-DTI-81 white matter atlas, which is a reference coordinate system containing the probabilistic locations of 50 white matter tracts, averaged from 81 different individuals9. The open-source software Analysis of Functional NeuroImages (AFNI) was utilized to extract FA and MD values. Spearman’s correlation test was performed between each WMT and clinical parameters both objective (9 parameters from uroflow and UDS such as PVR, BC, MCC, etc.) and subjective (19 parameters from validated questionnaires). Spearman’s correlation test was also performed between clinical parameters and the EDSS score as well. P-values < 0.05 were considered statistically significant.

Clinical parameters showing correlation with the highest number of WMTs are shown in Figure 1. Of these, %PVR/BC obtained from the average of multiple un-instrumented uroflow assessments had significant correlations to the greatest number of WMTs when assessing FA and MD. Furthermore, we observed that in all recorded clinical parameters, %PVR/BC had the strongest equivalence to the EDSS score (Figure 2).

%PVR/BC seems to be a suitable metric to evaluate VD in women with MS, where the bladder capacity can be variable and the absolute value of PVR may be unreliable. However, an important limitation exists: We must confirm that the regions of the white matter locus that correlate to the severity of VD in MS patients are localized to the same areas of the greatest white matter lesion burden.

Results from this study demonstrate that %PVR/BC can be used as a reliable, objective parameter with which to gauge voiding efficacy and response to therapy in MS patients.

Karmakar D, Sharma JB. Current concepts in voiding dysfunction and dysfunctional voiding: A review from a urogynaecologist's perspective [retracted in: J Midlife Health. 2018 Jan-Mar;9(1):50]. J Midlife Health. 2014;5(3):104-110. doi:10.4103/0976-7800.141185