Definition

Urge urinary incontinence is the complaint of involuntary leakage accompanied by or immediately preceded by urgency. Urge urinary incontinence is usually associated with involuntary contractions of the bladder or detrusor contractions. Strictly speaking, detrusor instability (DI) is an urodynamic definition and term. Recent questions about the relevance and reproducibility of the role of involuntary contractions in the clinical presentation of incontinence have been raised. The literature is at times confusing concerning the methodology (catheter type, bladder filling rate, provocative maneuvers, etc) for data acquisition. The literature is filled with many different terms describing DI, such as overactive bladder (OAB), bladder dyssynergia, uninhibited detrusor, and unstable bladder. In addition, when the cause of involuntary detrusor contractions is due to an underlying neurologic lesion, DI is called detrusor hyperreflexia. OAB is a term that lends itself to encompassing all conditions related to bladder urgency, frequency with and without incontinence. Overactive bladder has become a preferred term because it comprises symptoms of urgency, urge urinary incontinence, frequency, and nocturia.

Etiology

The incidence of OAB varies depending on the population studied and the definition applied. Consequently, the reported prevalence varies widely from 8-50% in the general population, and in women over 65 years it is estimated to be at least 38%. An important concept is that involuntary detrusor contractions for bladder emptying are normally overridden by cortical inhibition of reflex bladder activity. In the majority of cases the cause of OAB symptoms is unknown. Patients with underlying neurologic disease may manifest with urinary incontinence. Although neurologic disease is not a common cause of OAB, multiple sclerosis, cerebrovascular disease, Parkinson's disease, and Alzheimer's disease are most often associated with involuntary bladder contractions.

Urinary Incontinence Urinary Incontinence Anatomy   L Introduction   L Neuroanatomy Urinary Incontinence - Overview   L Definition   L Etiology   L History   L Patient Questionnaires   L Voiding Diary   L Urinalysis   L Physical Examination   L Cotton Swab Test   L Urinary Cough Stress Test   L Neurologic Examination   L Urodynamics   L Cystourethroscopy   L Imaging Tests Stress Urinary Incontinence   L Introduction   L Treatment Urge Urinary Incontinence Mixed Incontinence   L Introduction   L Treatment Overflow Incontinence   L Definition   L Etiology   L Diagnosis   L Treatment Bypass Incontinence Diverticulum Functional and transient incontinence References

Diagnosis

Diagnosis of OAB is suggested by urinary frequency often associated with a strong urge or a sense of impending urine loss. Incontinence often occurs prior to reaching the toilet. Loss of urine may occur seconds after stress, such as a cough or strain. Physical or environmental stimuli, such as running water, cold weather, or hand washing, may elicit an urge. Patients often describe "key in lock" syndrome. This is typically characterized by an uncontrollable urge to void when unlocking the door after returning from a trip out of the house. The first thing done upon return is to immediately rush to the toilet or risk losing urine.

Urge Urinary Incontinence Treatment

Adequate therapy depends greatly on accuracy of diagnosis of OAB. History is most often suggestive, and the diagnosis can be confirmed with office cystometry or more precisely with multichannel urodynamics.

Patients with OAB first should be offered simple treatments. Behavioral modifications and medical treatment are the standard first-line therapy for urge urinary incontinence.

A. BEHAVIORAL THERAPY

Behavioral therapy includes bladder training, timed voiding, and pelvic floor muscle exercises. Bladder training is an educational program that combines written and verbal instruction to educate patients about the mechanisms of normal bladder control with the teaching of relaxation and distraction skills to resist premature signals to urinate. Creating a voiding schedule for which the patient urinates at preset intervals while attempting to ignore the urge to urinate may progressively lead to re-establishment of cortical voluntary control over the micturition reflex.

Timed voiding is a form of bladder retraining that again mandates regularly scheduled voiding and attempts to match the person's natural voiding schedule. No effort is made to motivate the patient to delay voiding by resisting the urge. This method is geared more toward elderly patients with more challenging problems who have skilled help available.

Pelvic floor exercises may aid in the treatment of OAB. Evidence supports the utility of this modality in all types of incontinence. Particularly when augmented with biofeedback, pelvic floor exercises can greatly reduce symptoms of urinary frequency and urge incontinence, by up to 54-85%.

B. PHARMACOLOGIC THERAPY

One of the most effective and popular treatments for urge urinary incontinence and OAB is drug therapy. Numerous agents for the treatment of these patients have been tried over the years, but only a few have demonstrated substantial impact on reduction of symptoms in controlled trials. One of the main difficulties in treating OAB is that the cause of OAB is still under investigation. The drugs available can be divided into classes by mechanism of action (Table 45-8).

Antimuscarinics, or anticholinergics, have become the mainstay of drug treatment of OAB. Acetylcholine is the primary neurotransmitter involved with bladder contraction. The detrusor muscle of the bladder is heavily populated with cholinergic receptors. Anticholinergic activity, therefore, is a property of most drugs used to treat OAB. The prototype medicine is propantheline. Used for many years, it has excellent results in uncontrolled case series but only modest efficacy in controlled trials, providing benefit in up to 53% of patients.

The mainstays of drug therapy for OAB include oxybutynin chloride and tolterodine. Oxybutynin chloride has been shown in randomized placebo-controlled trials to be effective in increasing bladder capacity, decreasing the frequency of detrusor contractions, and improving symptoms of urinary urgency in approximately 70% of patients. It is effective for both idiopathic and neuropathic etiologies of DI.

Tolterodine is a medication designed specifically for OAB. It also has anticholinergic activity with specificity for the bladder, and it acts through muscarinic receptors as well as smooth muscle relaxation. In a multicenter randomized controlled trial, the medication compared favorably with oxybutynin in terms of reducing the number of micturitions in 24 hours and the number of incontinent episodes. Because of its bladder specificity, tolterodine has a more favorable side effect profile than oxybutynin. It is also dosed less frequently and improves patient compliance. Both are available in immediate-release and long-acting formulations. Oxybutynin is also available for delivery in a transdermal patch. Recently, a third antimuscarinic, trospium, has become available in the United States for treatment of OAB.

A large randomized comparative trial evaluating the performance of the long-acting formulations of oxybutynin and tolterodine demonstrated similar efficacy. Both reduced weekly urge incontinence episodes, but patients randomized to oxybutynin had a significant reduction in micturition frequency compared with patients receiving tolterodine, and significantly more patients taking oxybutynin became totally dry (23% vs 16%). Adverse events were similar, but the occurrence of dry mouth was higher in the oxybutynin group.

Two new antimuscarinics are solifenacin and darifenacin. Both significantly improve OAB symptoms compared to placebo. Evidence suggests that their side effects will be similar or lower than those of currently available antimuscarinics.

Imipramine hydrochloride is a tricyclic antidepressant that acts through its anticholinergic properties to increase bladder storage. The drug improves bladder compliance rather than counteracting uninhibited detrusor contractions. It is given in doses greatly reduced from those recommended for use as an antidepressant. It also has pharmacologic activity in the blockade of postsynaptic noradrenaline uptake and thereby increases bladder outlet resistance. With its dual action, imipramine may be effective in patients with both stress incontinence and DI (mixed incontinence). It has a low rate of discontinuation because of the main side effects of tremor and fatigue, but it should be dosed in the evening because it may have a sedative effect, and it should be used with caution in elderly patients because of potential orthostatic hypotension.

Surgical measures are methods of last resort for severe intractable DI. Recently, the InterStim surgically implantable device has been found to be effective in patients with intractable urinary urgency and voiding dysfunction.