In people with an overactive bladder (OAB), the detrusor muscle (layered smooth muscle that surrounds the bladder) contracts spastically, sometimes without a known cause, which results in sustained, high bladder pressure and the urgent need to urinate (called urgency). Normally, the detrusor muscle contracts and relaxes in response to the volume of urine in the bladder and the initiation of urination.
People with OAB often experience urgency at inconvenient and unpredictable times and sometimes lose control before reaching a toilet. Thus, overactive bladder interferes with work, daily routine, and intimacy; causes embarrassment; and can diminish self-esteem and quality of life.
Urination
Urination (micturition) involves processes within the urinary tract and the brain. The slight need to urinate is sensed when urine volume reaches about one-half of the bladder's capacity. The brain suppresses this need until a person initiates urination.
Once urination has been initiated, the nervous system signals the detrusor muscle to contract into a funnel shape and expel urine. Pressure in the bladder increases and the detrusor muscle remains contracted until the bladder empties. Once empty, pressure falls and the bladder relaxes and resumes its normal shape.
Incidence and Prevalence
Overactive bladder affects men and women equally and increase with aging. The U.S. Department of Health and Human Services has reported that approximately 13 million people in the United States suffer from OAB and other forms of incontinence, but recent estimates suggest that 16% of the US population or 33 million adults have OAB according to current ICS (International Continence Society) guidelines. Suprisingly, only 1/3 have coexisting incontinence and therefore the remaining 2/3 do not either seek or get offered treatment despite the fact that it significantly impact their quality of life, and that currently offered treatment modalities are safe and effective.
Causes
Malfunctioning detrusor muscle in the smooth muscle of the bladder causes overactive bladder. Identifiable underlying causes include the following:
-
Nerve damage caused by abdominal trauma, pelvic trauma, or surgery
-
Bladder stones
-
Drug side effects
-
Neurological disease (e.g., multiple sclerosis, Parkinson's disease, stroke, spinal cord lesions)
-
Other conditions can produce symptoms similar to those experienced with overactive bladder, the most common of which is urinary tract infection (UTI) in women.
Signs and Symptoms
Four symptoms are associated with an overactive bladder:
-
Frequency (frequent urination during the day)
-
Nocturia (frequent urination at night)
-
Urgency (urgent need to urinate)
-
Urge incontinence (strong need to urinate followed by leaking or involuntary and complete voiding
Treatment
Treatment may include one or more of the following:
Medication
Drugs such as oxybutynin chloride (Ditropan XL®) and tolterodine (Detrusitol®, Detrol LA®) are taken orally, once a day, for overactive bladder. They can improve symptoms within 2 weeks. These drugs (antimuscarinics) affect the central nervous system and muscarinic receptors in smooth muscle. They relax the smooth muscle of the bladder, which reduces detrusor contraction and subsequent wetting accidents. In a recent study, participants taking Ditropan XL had 90% fewer accidents, used fewer protective pads, and experienced 24-hour relief from urgency and loss of control.
Side effects, including dry mouth, constipation, headache, blurred vision, hypertension, drowsiness, and urinary retention occur in approximately 50% of those who use the drugs. People with glaucoma or certain types of kidney, liver, stomach, and urinary problems are advised not to take Ditropan XL. Although there is no evidence that Ditropan XL causes birth defects, pregnant women should not take it without consulting a physician.
Recently introduced, the oxybutynin transdermal system (Oxytrol™) is a thin, flexible, clear patch that is applied to the skin of the abdomen or hip, twice weekly, to treat overactive bladder. This treatment delivers oxybutynin continuously through the skin into the bloodstream and relieves symptoms for up to 4 days.
Patients who have urinary or gastric retention, uncontrolled narrow-angle glaucoma, and those with hypersensitivity to oxybutynin should not use the oxybutynin transdermal system.
Side effects are usually mild and include adverse reactions at the site of application, dry mouth, and constipation.
Sacral Nerve Stimulation
InterStim® therapy is a reversible treatment for people with urge incontinence caused by overactive bladder who do not respond to behavioral treatments or medication. InterStim is an implanted neurostimulation system that sends mild electrical pulses to the sacral nerve, the nerve near the tailbone that influences bladder control muscles. Stimulation of this nerve may relieve the symptoms related to urge incontinence.
Prior to implantation, the effectiveness of the therapy is tested on a outpatient basis with an external InterStim device. For a period of 3 to 5 days, the patient records voiding patterns that occur with stimulation. The record is compared to recorded voiding patterns without stimulation. The comparison demonstrates whether the device effectively reduces symptoms. If the test is successful, the patient may choose to have the device implanted.
The procedure can be performed under local anesthesia on an outpatient basis. A lead (a special wire with electrical contacts) is placed near the sacral nerve and is passed under the skin to a neurostimulator, which is about the size of a stopwatch. The neurostimulator is placed under the skin in the upper buttock.
Adjustments can be made at the doctor's office with a programming device that sends a radio signal through the skin to the neurostimulator. Another programming device is given to the patient to further adjust the level of stimulation, if necessary. The system can be turned off at any time.
Possible adverse effects include the following:
In addition to treatment of urge incontinence, overactive bladder symptoms, and refractory voiding dysfunction, the Interstim device has successfully been used to treat refractory interstitial cystitis, fecal incontinence, and pelvic pain-giving new hope to many women who have long suffered from these debilitating conditions despite multiple treatment attempts. Over the last six months, the technique has become minimally invasive and associated with significantly fewer complications. In addition, it has received greater widespread insurance coverage.
SANS is a form of peripheral nerve stimulation done through an acupuncture needle placed in the lower leg and attached to a small external stimulator. The treatment consists of a half-hour session electrical stimulation-neuromodulation and is done weekly for eight to 10 weeks. There are minimal risks and significant benefit to appropriately selected patients. Many patients select this form of neuromodulation prior to considering the more invasive Interstim therapy.
Send Feedback to: 
