09/10/2009 - Articles

The Overactive Bladder

By: Robert W. Griffith, MD

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Symptoms of an overactive bladder - urgency (needing to "go" right away), incontinence (leaking of urine), and getting up 2-3 times at night to urinate - interfere with people's social activities and quality of sleep, leading to isolation and depression. Here's an overview of the situation at present.

The Overactive Bladder

Summarized by Robert W. Griffith, MD
October 29, 2004

Introduction

A telephone survey of people over 40 in Europe showed that 16% of men and 17% of women reported symptoms of an overactive bladder - urgency (needing to "go" right away), sometime accompanied by incontinence (leaking of urine), and nocturia (having to get up 2-3 times at night to urinate). Urgency and incontinence interfere with people's social activities, leading to isolation and depression, while nocturia disturbs sleep and thus decreases the quality of life.

Some physiology

The cause of an overactive bladder (which by definition means there is no disease process involving the bladder and urinary tract) is clearly due to disturbed nervous system control of the bladder, especially that involving the detrusor muscle, which normally contracts to empty the bladder during urination (voiding). Overactivity of the detrusor muscle results in urgency or urge incontinence, depending on how well the urethral sphincter is working (the urethral sphincter is the muscle that keeps the urethral closed, and prevents voiding).

A number of chemicals called neurotransmitters, which act as messengers between the nerves and the muscles they control, are involved in urinary voiding. Acetylcholine is the most important; it interacts with receptors on the detrusor muscle, which are called muscarinic receptors. There are five known subtypes of muscarinic receptors, but one known as M3 is the most relevant for urination.

In an overactive bladder, there is sometimes an increased sensation of fullness sent from the bladder to the spinal cord, which can lead to contraction of the bladder.

Before treatment starts

A full diagnostic workup must be done to ensure that the proposed treatment matches the probable cause of the symptoms. This may include a detailed history, a focused physical exam, urinalysis, and, in some cases, catheterization, an ultrasound exam, and cystoscopy (passage of a thin viewing tube into the bladder). Some experts suggest so-called urodynamic testing, in which the urinary flow rate and the residual urine after voiding are measured, but this is controversial.

Treatment of an overactive bladder

Any abnormal local conditions, such as cystitis (a bladder infection) or prostate enlargement, should be treated accordingly. Otherwise, there are non-drug and drug treatments.

Non-drug treatments involve appropriate education of the patient, avoidance of caffeine, changes in the timing of fluid intake, and the use of bedside commodes or urinals. Behavioral therapy, which consists of 'bladder training' and pelvic-muscle exercises, has a positive effect within 3 months in as many as 70% of patients with incontinence. Biofeedback1 can improve the effectiveness of pelvic-muscle exercises and timed voiding.

Other non-drug measures include the use of highly absorbent pads and undergarments, and, in selected cases, electrical stimulation or even surgery to destroy some nerves to the bladder.

Drug treatments are of three kinds: anticholinergic or anti-muscarinic drugs, estrogens for women, and 'alpha-blockers' for men (these are a type of blood pressure-lowering drugs that are also useful in prostate enlargement).

The anticholinergic drugs are the most popular treatment for overactive bladder. Oxybutynin, propiverine, tolterodine, and trospium have all been shown to be safe and effective. 'Safe' doesn't mean free of side effects; anticholinergics can cause dry mouth, constipation, gastroesophageal reflux (GERD), blurred vision, and urinary retention (blockage of urination). Oxybutynin (Ditropan®) is available in a slow-release form, and as a skin patch (Oxytrol®). It cuts urinary incontinence episodes by half in 60% to 80% of people with the problem. Tolterodine (Detrol®) is equally effective, and is also available in a long-acting form.

Estrogen is often given to postmenopausal women, either orally or as a cream or lotion, but there is little evidence that it's effective in relieving the symptoms. In men, the symptoms of overactive bladder often overlap those of prostate enlargement, which can be treated medically with an alpha-blocker. These drugs can cause very low blood pressure on standing up, so the first dose must be small, and then the doses increased very gradually. Doxazosin (Cardura®), prazosin (Minipress®), and terazosin (Hytrin®) are the most commonly prescribed alpha-blockers.

Two other drugs that are occasionally used in overactive bladder are imipramine (an antidepressant) and desmopressin - given orally or as a nasal spray, chiefly in children. Effectiveness is questionable, and side effects are considerable.

Future directions

Many drugs from different classes are in clinical trials for effectiveness and safety in people with an overactive bladder. More specific anti-M3 muscarinic blockers are in development, as well as other types of drugs attacking different points in the disrupted physiology. It is to be hoped that this distressing complaint, although not serious, will soon be easily managed with newer, specific treatments.

Source

  • Management of overactive bladder. JG. Ouslander, N Engl J Med, 2004, vol. 350, pp. 786--799
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You can read more about all this in the Health Center: Bladder Problems.

Footnotes
1. Biofeedback uses measuring devices to help make you aware of your bladder's functioning. By tracking when your bladder and urethral muscles contract, you can gain control, using timed voiding, pelvic muscle exercises, and/or electrical stimulation.

Related Links
Overactive Bladder? - There's No Miracle Cure, Yet
Bladder Problems

Created on: 10/25/2004
Reviewed on: 09/10/2009

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