Multiple sclerosis (MS) is the most common neuro-inflammatory disease of the central nervous system and is a leading cause for lower urinary tract (LUT) dysfunction in neurological patients. Neurogenic overactive bladder (nOAB), defined as presence of urinary urgency usually accompanied by increased daytime  frequency with or without urinary incontinence(1), is common in MS patients; a voiding dysfunction (VD), defined by the ICS in female patients as “abnormally slow and/or incomplete micturition, based on abnormally slow urine flow rates and or abnormally high post-void residuals”(2), may also be present in these patients. The aim of this retrospective epidemiological study was to understand the prevalence of storage and voiding symptoms, nOAB and VD in MS patients and to investigate their prevalence in male and female patients separately.

Patients with a diagnosis of MS at their first visit in a single neuro-urology centre were evaluated. Age, sex, type of symptoms were recorded; data related to clean intermittent catheterisation (CIC) regime were also recorded. Uroflowmetry and post-void residual (PVR) evaluation were performed and collected. nOAB was defined according to the previously cited definition; VD was defined as the presence of at least one voiding symptom plus a reduced urinary flow (defined as Qmax <13 ml/s or  <10 ml/s in males older than 65 years) or elevated PVR (defined as ≥100 ml). Basing on these findings, patients were divided in three groups: nOAB, VD, and OAB+VD. The prevalence of these three conditions was also analysed separately in male (M) and female (F) patients. Statistical analysis and use of chi-squared test were applied.

A total of 114 patients (age range 22-77 years; average age 48,7 years; M=49, F=65) were included. Of them, 104 (91%) reported to be bothered by LUTS: 42/49 M (86%) and 62/65 F (95%). nOAB and VD were found in 91 (80%) and 64 (56%) patients, respectively. Table 1 reports the prevalence of the difference storage and voiding symptoms as reported by patients. Basing on the symptoms and on uroflowmetry data and PVR evaluation, patients were categorised as nOAB only (53/114), DU only (8/114), and OAB+DU (38/114); in particular 38/91 patients (41,8%) of patients with nOAB showed also a VD. Comparing the distribution of nOAB and VD among sexes, it was observed that while the prevalence of VD was similar (M vs F: 41% vs 40%), OAB was found in 89% of F and in 67% of M. Also, an elevated PVR was slightly more common among women than men (18% vs. 10%), whilst the opposite was observed for low urine stream (F vs. M: 26% vs. 35%). Interestingly, the presence of VD alone was significantly higher in M than in F (M:F = 7:1, pvalue < 0.05).

According to this study, urgency and frequency are the most common urinary symptoms (68%), followed by urge incontinence (55%) and nocturia (48%). Voiding symptoms are reported by 61% of MS population, especially feeling of incomplete emptying (34%) and weak urine flow (32%).
The most common urological syndrome in MS patients seems to be nOAB, especially for women (M 67%, F 89%). According to our data, even though VD barely occur alone, this condition is present in around 44% and voiding symptoms are reported by more than 60% of our cohort. In particular, VD is quite common in nOAB patients, with a prevalence of around 42%. Analysing the distribution of OAB and VD, data show that LUTS in 1/3 of the patients are due to a combination of nOAB and VD, with insignificant differences between males and females (M vs. F: 27% vs 38%). Nevertheless, signs of VD alone seems to be significantly higher in M than in F.

This epidemiological retrospective study confirms that nOAB is the most common LUT syndrome among the MS population; in particular, OAB symptoms are reported by almost 90% of women. According to our data, VD symptoms are also common, being present in around 40% of MS patients; regardless the sex, and 1/3 of our patients presents signs of both OAB and DU. Around 42% of nOAB show also VD. We believe that it is important to underline that, even if nOAB is more prevalent, VD is common in MS patients and may be present in 42% on nOAB patients, thus conditioning the following therapeutic strategy.

Gazewski JB, Schurch B, Hamid R, Averbeck M, Sakakibara R, Finazzi Agro E, Dickinson T, Payne C, Drake MJ, Haylen BT. An International Continence Society (ICS) Report on the Terminology for Adult Neurogenic Lower Urinary Tract Dysfunction (ANLUTD) Neurourol Urodyn 2017 Nov 17 DOI: 10.1002/nau.23397
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