Overactive Bladder

The overactive bladder is defined as a bladder storage / filling disorder, where involuntary bladder contractions occur, causing patient’s symptoms. It is most commonly due to idiopathic detrusor overactivity; but in the presence of neurological diseases, it is known as neurogenic detrusor overactivity.

Prevalence

The overall prevalence in the general population is 10%. It increases with age; especially after the age of 30 years. It is much higher in menopausal, elderly, hospitalized or nursing home patients.

The typical clinical presentation includes urgency and/or urge incontinence, frequency and nocturia, with urgency being the commonest symptom. Any one or a combination of these symptoms can occur. The less common is the symptom of bed wetting (nocturnal enuresis). Abdominal pain and pain during urination (dysuria) are not common symptoms of OAB.

Causes of Overactive Bladder

In 90% of women with OAB, no recognizable cause can be found – Idiopathic detrusor overactivity. Other known causes include neurologic disease, inflammation, previous pelvic surgery, pelvic organ prolapse, psychosomatic diseases and orgasm.

Physical Examination

General physical and neurological examinations should be performed. It is unusual, however, for a neurological examination to reveal unsuspected neurological dysfunction.

Investigations

An initial evaluation should include an assessment of the patient's symptoms, detailed physical examination and urinalysis.

Once urinary tract infection has been excluded, it is possible to establish a working diagnosis based on the patient's description of symptoms. In cases where there is uncertainty regarding the diagnosis, more advanced investigations should be carried out.

These include:

• Urine cytology - To detect bladder tumour
• Frequency Volume Chart - A chart of the timing and volume of output to indicate the severity of the problem. Follow-up charts are also useful to provide evidence of a response to treatment
• Filling and Voiding Cystometry - Cystometry is the mainstay of investigation and is the only method of objective assessment of overactive bladder
• Ambulatory Urodynamics - Only for patients in whom a routine cystometry in a laboratory setting cannot elicit detrusor contractions
• Cystoscopy - To look for bladder stone, tumour or inflammation

Management of Overactive Bladder

Bladder Retraining

It constitutes a program of scheduled voiding with progressive increase in the interval between each void. The cure rate of 80% has been reported. A 12-week program is anticipated.

Electrical Stimulation

It stimulates the pelvic floor and urethral muscles, and inhibits detrusor muscle contractility. A 50% cure rate has been reported. The main difficulty is with patient acceptance.

Drug Therapy

It is the most popular mode of treatment in patients with overactive bladder. However, the response is often dose-related and side effects are common at effective doses. In general, drugs improve detrusor instability by inhibiting the contractile activity of the bladder.

The maximum dose is usually determined by patient tolerance to the side effects.

Anticholinergic Agents

• Oxybutynin chloride: It is the probably the most effective drug. The side effects are common and include dry mouth, constipation, blurred vision, dizziness that can be unbearable and cause some patients to discontinue its use. Symptomatic improvement can be seen in about two-thirds of patients.
• Tolterodine: It causes a 20% or more reduction of frequency of micturition and a 45% reduction in incontinence episodes. Because of bladder selectivity, it has less systemic side effects, particularly dry mouth as compared to oxybutyin.

Tricyclic Antidepressant

Imipramine hydrochloride: It improves bladder storage significantly. It appears to improve bladder hypertonicity or compliance rather than uninhibited contractions. It is useful in patients with enuresis. The side effects are anticholinergic, as well as tremor and fatigue. It can also cause orthostatic hypotension.

Synthetic Vasopressin

DDAVP: It decreases urine production. It is helpful in patients with troublesome nocturnal urinary symptoms. However, its use in the elderly and patients with heart problem is limited.

Important Points To Remember In Drug Therapy

• Each drug should be given for at least 6 weeks before deeming it a failure, as the onset of benefit may be delayed
• Each drug must be titrated, based on subjective response and its side effects
• If one drug is not beneficial, it is worth trying other drugs with different modes of action or combining drugs
• Overactive bladder is a relapsing and remitting condition

Surgical Treatment

It is only used as a last resort in the management of overactive bladder.

Mixed Incontinence

Overactive bladder can co-exist with stress urinary incontinence / urodynamics stress incontinence in up to 30% of patients. Medical management of the overactive bladder reduces the need for bladder continence surgery. If patients fail medical treatment, bladder neck surgery may be recommended. However, patients should understand that the post-operative course of detrusor instability is somewhat unpredictable. They may need to continue medical treatment for their overactive bladder.