Multiple sclerosis is a central nervous system disease characterized by an autoimmune mediated inflammatory demyelination, marked by lesions separated by time and space. It is a disease that results in severe disability due to the wide range of comorbid problems that occur as the disease progresses.
The two major functions of the bladder are storage and emptying of urine. Bladder control is complex and requires coordination of function of the cerebral cortex, peripheral nervous system, and pontine and sacral micturition centers. Demyelinating lesions may impair both sensory and motor function.
Patients with multiple sclerosis may often have motor impairment in their lower extremities, and this impairment may be accompanied by bladder sphincter dysfunction. As the lesions of multiple sclerosis progress to demyelination of the sacral spinal nerves, patients may experience neurogenic bladder and the sequelae, which include infections, renal calculi, renal failure, and vesicoureteral reflux.
Patients commonly complain of urinary urgency resulting from uncontrolled contraction of the detrusor muscle as a result of a suprasegmental lesion. This can produce bladder spasms, urgency, frequency, and incontinence. Hyperactivity of the bladder sphincter may impair the patient’s ability to empty the bladder completely. A lack of coordination between the actions of the detrusor and sphincter, known as detrusor sphincter dyssynergia, may lead to contractions of the bladder against a closed sphincter, elevating pressure within the bladder and resulting in vesicoureteral reflux.
With disease progression and increased involvement of the sacral segments of the spinal cord, patients may experience bladder hypoactivity, including decreased urinary flow, interruption of micturition, and incomplete voiding. The resulting atonic bladder becomes dilated and empties by overflow as a result of loss of the sensation of fullness. At the same time, sensory deficits in the sacral dermatomes are not uncommon, nor is hypesthesia in urethral, anal, and genital regions.
Bladder symptoms self-reported in one study of 297 patients with multiple sclerosis did not correlate with post-micturition residual bladder volume, and the authors of that study suggest ultrasound scanning for residual urinary volume in all patients with multiple sclerosis, whether or not they have subject urinary symptoms. 1
Other clinicians recommend post-void residual scanning in patients who are symptomatic before the initiation of therapy with an anticholinergic medication.2
As with any management strategy for bladder problems associated with lesions of the central nervous system, the goal of treatment is to avoid complications, including retention and infection, and to enable the patient to minimize episodes of incontinence. Before proceeding with treatment of urinary symptoms in patients with multiple sclerosis, infection and other causes of urinary urgency and incontinence should be ruled out. Urodynamic studies may be in order to assess the pathophysiology of any urinary tract dysfunction.3
Treatment strategies for bladder dysfunction in patients with MS should target the suppression of urgency and the continued effectiveness of urinary drainage. A stepwise approach to treatment of the problems associated with sphincter dysfunction includes fluid restriction to less than 2 liters per day, coupled with timed voiding. Medical therapies have long consisted primarily of anticholinergic and antimuscarinic drugs.4
Oxybutynin is the first-line medication for bladder dysfunction, given in doses of 2.5 to 5 milligrams one to three times daily. It may also be given as an extended-release preparation or as a transdermal patch. Tolterodine is another first-line anticholinergic therapy, and is also available in a long-term preparation.
Clean technique intermittent catheterization can be performed at regular intervals to achieve a bladder volume of less than 500 cc of urine. This technique has a lower rate of infection when compared to long-term catheterization. However, voluntary voiding in response to a sensation of fullness is encouraged.
Botulinum toxin injection is one treatment option for neurogenic bladder detrusor overactivity in patients for whom anticholinergic or antimuscarinic therapy is intolerable or ineffective. Several trials that have included patients with MS or spinal cord injury utilizing onabotulinumtoxinA injections into the detrusor muscle have shown that this therapy is more effective than placebo for reduction of urinary incontinence and for improvement in measures of quality of life.5 A side effect may be urinary retention, requiring clean technique intermittent catheterization.
Despite these therapeutic measures, there will still be intermittent urinary incontinence, and condom catheters or adult diapers are necessary short-term interventions.