Urological dysfunction in multiple sclerosis

Lower urinary tract symptoms have been recognized quite early as a serious and frequent problem in multiple sclerosis. We present a review of studies of these symptoms and of their incidence in multiple sclerosis (MS). According to the study, 46 to 78% of patients with MS will develop symptoms from the lower urinary tract at some moment during the course of the disease, but most of the studies agree at a frequency of about 75%. Symptoms seem to be more frequent in the primary progressive form of multiple sclerosis. It is not frequent however to find these symptoms as presenting features of the disease unless they are part of a spinal syndrome. Studies have shown that their presence in early phases of the disease concerns about 7 to 10% of the patients. Symptoms from the lower urinary tract have been commonly termed "irritative" and "obstructive", the terms describing the problems related to the capacity of storage of the bladder and the frequency and completeness of bladder voiding respectively. Specifically, the sudden compelling desire to pass urine, difficult to defer, is termed "urgency", "increased daytime frequency" is the complaint of voiding too often by day, associated with nocturia, which concerns nighttime frequent voiding, and "urge incontinence" is the involuntary leakage accompanied or preceded by urgency. Thus, the more frequently encountered symptoms in patients with MS are urgency (24-86%), frequency (17-82%) and urge incontinence (19-72%). Less frequent are hesitancy (difficulty in initiating micturition and delay in the onset of voiding) and retention; the latter refers either to difficulties of micturition or hesitancy and, therefore, incidence of complete retention of urine is not known. Combinations of symptoms are also frequent, the most frequent being the combination of urge incontinence with intermittent urinary flow. Symptoms may appear in the form of episodes or relapses, or progressively. They have a particularly negative impact on the patients' quality of life and they cause major concern to their family and caregivers. It has been found that the urinary problems can be severe enough to prevent the patient leaving home in 19% of cases, attending social functions in 15%, or working in 1%. Urodynamic studies allow the description of the functioning of the lower urinary tract in laboratory conditions. Most of the symptoms presented are thus explained by bladder detrusor overactivity and by incomplete bladder emptying. Detrusor overactivity, characterized by involuntary detrusor contractions during the filling phase of bladder, is the most common cystometric finding in patients with urinary symptoms and is related to urgency, frequency and urge incontinence. Detrusor sphincter dyssynergia is a detrusor contraction concurrent with an involuntary contraction of the urethral and/or periurethral striated muscle and it is due the loss of coordinated action between detrusor and external sphincter. It may produce an interrupted urinary flow and incomplete bladder emptying. The latter can result in post void residual and it may be of importance as it may be responsible for infections and related to complications from the upper urinary system. It seems however, that unlike in spinal cord injury patients, upper tract deterioration occurs infrequently in patients with multiple sclerosis; the reasons for this are unclear. Investigation of the relation between urinary symptoms and neurologic symptomatology has shown a correlation with the presence of pyramidal syndrome in the lower limbs and with the severity of motor impairment. On the other hand, investigation of the relation between bladder dysfunction and lesion site in the central nervous system in MS has shown a correlation with the presence of spinal and mesencephalic lesions. It seems that the lesion site in the central nervous system may be a major determinant of the type of bladder and urethral sphincter dysfunction. Neurologists need to look into these problems and they must know how to investigate them clinically. Urodynamic control is always necessary though most of the symptoms can be treated by conservative means.

Key words: Multiple sclerosis, bladder, urodynamics, lower urinary tract disorders.