Key points

Introduction

Multiple sclerosis (MS) is an autoimmune inflammatory disease that results in damage to the myelin sheaths of the nerves in the central nervous system. MS is commonly diagnosed between the ages of 20 and 40 and affects women 3 times more often than men. Reportedly, 80% to 96% of all patients with MS will seek urologic care because of bothersome lower urinary tract symptoms (LUTS) at some point in their disease course, and as many as 12% may have symptoms before their actual diagnosis. For the purposes of this review, all patients are considered who have LUTS secondary to MS as having neurogenic lower urinary tract dysfunction (NLUTD). Another term that is commonly used in this population is neurogenic bladder (NGB). In the strictest of senses, patients with NGB suffer from some type of bladder dysfunction secondary to an underlying neurologic condition, although this terminology is commonly applied to a broader range of dysfunctions.

Urinary urgency, frequency, and urgency incontinence are the most common symptoms reported by patients with MS, occurring in 37% to 99% of patients. Voiding symptoms (hesitancy, feeling of incomplete emptying, and occasionally urinary retention) are also common in this population, occurring in 34% to 79% of patients. Traditionally, filling cystometry combined with pressure/flow studies (that will be now referred to as urodynamic studies or UDS) have been a cornerstone of the initial evaluation of patients with NLUTD, although recently that practice has been challenged. In this review article, the role of UDS in the diagnosis and management of patients with MS is focused on, along with data published within the past 15 years.

Introduction

Multiple sclerosis (MS) is an autoimmune inflammatory disease that results in damage to the myelin sheaths of the nerves in the central nervous system. MS is commonly diagnosed between the ages of 20 and 40 and affects women 3 times more often than men. Reportedly, 80% to 96% of all patients with MS will seek urologic care because of bothersome lower urinary tract symptoms (LUTS) at some point in their disease course, and as many as 12% may have symptoms before their actual diagnosis. For the purposes of this review, all patients are considered who have LUTS secondary to MS as having neurogenic lower urinary tract dysfunction (NLUTD). Another term that is commonly used in this population is neurogenic bladder (NGB). In the strictest of senses, patients with NGB suffer from some type of bladder dysfunction secondary to an underlying neurologic condition, although this terminology is commonly applied to a broader range of dysfunctions.

Urinary urgency, frequency, and urgency incontinence are the most common symptoms reported by patients with MS, occurring in 37% to 99% of patients. Voiding symptoms (hesitancy, feeling of incomplete emptying, and occasionally urinary retention) are also common in this population, occurring in 34% to 79% of patients. Traditionally, filling cystometry combined with pressure/flow studies (that will be now referred to as urodynamic studies or UDS) have been a cornerstone of the initial evaluation of patients with NLUTD, although recently that practice has been challenged. In this review article, the role of UDS in the diagnosis and management of patients with MS is focused on, along with data published within the past 15 years.

Urodynamic findings in patients with MS

Among patients with MS, the most common UDS finding is neurogenic detrusor overactivity (NDO) seen in up to 70% of patients, although considerable variation exists depending on the population studied. It is theorized that in patients with MS, NDO results from the loss of inhibitory cortical influence of brain stem activity. In contrast, the cause of idiopathic detrusor overactivity (IDO), which represents detrusor overactivity (DO) seen in patients without known neurologic conditions, is less clear, although myogenic, undiagnosed neurogenic, and ischemic causes have all been suggested. Data from a recent study suggest that, in-line with the above physiologic explanation, DO seen in MS differs from that seen in nonneurogenic patients. In 2006, Lemack and colleagues investigated the differences between NDO in MS patients and IDO in patients without any neurogenic cause. The authors examined amplitude of first involuntary detrusor contraction (IDC), maximal detrusor contraction, and threshold volume for the first IDC as a measure severity of DO. Patients with MS and NDO had significantly higher amplitude of first IDC (28.3 cmH ₂ O vs 20.5 cmH ₂ O, P = .003). Similarly, NDO patients had a significantly higher maximal detrusor contraction, 46.4 cmH ₂ O, as compared with IDO patients, 30.8 cmH ₂ O ( P = .002). Last, the threshold volume for DO was greater in the MS patients (186.8 mL vs 150.5 mL, P = .037), which the authors attributed to the larger postvoid residual (PVR) in the MS patients. These findings were in concert with a 1997 study by Gray and colleagues, who also noted that patients with MS had higher amplitudes of IDCs as compared with nonneurogenic controls. In addition, MS patients had higher PVRs when compared with nonneurogenic patients.

Others have similarly found DO to be the most common urodynamic finding followed by detrusor sphincter dyssynergia (DSD) (25%), although the variance in prevalence rates between this and other studies reflects the importance of recognizing the particular population surveyed, and the urodynamic definitions used. A recent meta-analysis of the evaluation and management of LUTS in MS noted NDO (25%–100%) and DSD (3%–71%) as the most common UDS findings. Detrusor underactivity or acontractility was seen in 8% to 70%, and altered compliance was found in 7% to 10% of patients.

Urinary symptoms in patients with MS

As NDO is the most common UDS finding seen in patients with MS, numerous studies have shown that storage symptoms (such as urgency, frequency, and urgency incontinence) are the most common LUTS reported by these patients. Depending on the population surveyed and the survey tool used, a prevalence of 10% to 100% for LUTS has been reported. Hennessey and colleagues investigated urinary, fecal, and sexual dysfunction in patients with MS. Of 191 patients queried, 53% reported bothersome urologic symptoms, with symptoms of urinary frequency and urgency being much more prevalent than voiding/emptying symptoms. Specifically, some degree of urinary frequency was observed in 177 of 191 (93%) patients. Overall, 145 of 191 (76%) were noted to void more than 5 times a day and 32 of 191 (17%) more than 10 times a day. Interestingly, in this group, 71% of patients reported some degree of urgency incontinence. Chronic catheter use was fairly infrequent in this group. Although 55 of 221 (25%) patients had required the use of a urinary catheter at some point in their disease process, only 6 of 221 (3%) used clean intermittent catheterization on a regular basis. A recent study of 66 patients noted storage symptoms to be more common than emptying symptoms. Specifically, urinary urgency was the most common symptom (65%), followed by frequency (44%) and urgency incontinence (42%).

Although both LUTS and UDS findings are subject to change over time, the LUTS progression does not seem to be inevitable in patients with MS. A 2001 study retrospectively evaluated 22 patients with MS and LUTS over a 14-year period. All patients underwent 2 or more UDS during this time as a means of studying their LUTS. Fourteen of the 22 (64%) patients had stable or worsening of the same symptoms at follow-up and 8 of 22 (36%) had new symptoms of incontinence, obstructive, or irritative symptoms. Six of the 14 patients who did not develop new urinary symptoms were found to have significant changes in UDS patterns, including altered compliance. The data from this small study are not sufficient to conclude that repeated urodynamic investigations are warranted in patients without change in symptoms, baseline renal or urodynamic abnormalities, or patients deemed to be at high risk.

In summary, UDS may be helpful in identifying the type of NLUTD in patients with MS. NDO is the most common UDS observation in symptomatic patients, and storage symptoms, such as urinary urgency and frequency, are the most common symptoms described. Still, the relationship between urinary symptoms and UDS findings in patients with MS requires further scrutiny.