July 6, 2012
Dear Mayo Clinic:
What are the causes of detrusor instability? I often have the urge to urinate but then can only go in small amounts. Is there a way to treat it?
Detrusor instability — meaning that the bladder is contracting even when it shouldn't be — is a diagnosis made from a complex urodynamic study. Likely, what you are referring to is an overactive bladder (OAB). Urgency and frequency of urination are the symptoms of an overactive bladder. Having a "stable" or "unstable" bladder muscle on urodynamic testing does not necessarily mean you have the symptoms of an overactive bladder. It is your symptoms that make the call of OAB, not the term detrusor instability. So let's talk about OAB.
With OAB can come a sudden intense urge to urinate that is difficult to suppress and can result in incontinence of urine. Patients with this condition may find that they have to urinate often. Others may not have frequency, but could still have incontinence as the bladder "fires off" very rapidly. For many, especially men, this intense urge is just a bothersome sensation, and no leakage occurs.
Urgency and frequency symptoms can have many causes. The most common is a urinary tract infection. So, the first step is a urine sample to rule out infection, blood in the urine or tumor. If that test is normal, your doctor likely will obtain a history and perform a brief physical to ensure that the bladder is emptying. If potential causes of OAB are ruled out, the next step is treating the symptoms of OAB. If the urine is abnormal, evaluation by a urologist is likely the next step.
For men, women and children with simple OAB, the best treatment is usually behavioral. A diary of your fluid intake and voiding habits is very helpful in planning your treatment. Often, a combination of treatment strategies is effective and may include timed voiding, fluid consumption schedules, and pelvic floor muscle exercises. Within two to three months, these measures may allow you to suppress your symptoms. About 60 to 75 percent of patients see a definite improvement in their quality of life. Many are cured.
Your doctor may suggest trying a medication to relax the bladder to help alleviate symptoms. A number of medications are available. Because they are from the same class of drugs, all are associated with side effects, including the possibility of dry eyes and mouth, a feeling of thick-headedness or constipation. Your doctor may have you try several different medications to determine which has the fewest side effects and still control your symptoms.
If behavioral interventions combined with medication is not effective, neuromodulation — typically sacral nerve stimulation (InterStim) — might be an option for some people. Thin electrodes are inserted close to the sacral nerves to deliver low level electrical impulses to your pelvic floor.
Another treatment option that may be available in the future is onabotulinum toxin A or Botox injections into the bladder muscle to prevent the bladder from firing off on its own. Onabotulinum toxin A is an effective treatment but it is important to note that is not approved by the Food and Drug Administration (FDA) for this indication and must be repeated about every 6 to 9 months if it is successful.Bladder onabotulinum toxin A injections are sometimes associated with an inability to pass urine and with urinary tract infections.
Neither bladder injections with onabotulinum toxin A or neuromodulation will reduce urinary tract infections or help with bladder pain. They are expensive and can have annoying complications. Although most patients' symptoms can be improved without surgery, the last resort is invasive surgery to enlarge the bladder using a section of theirbowel. Many who have this surgery need to intermittently catheterize their bladders for the rest of their life. Artificial bladder creation by substitution with other materials or bladder transplants is not yet a reality for sufferers of intractable OAB.
Some people cannot hold their urine because of declining cognitive function. Their bladders are fine, but their brains can no longer tell the bladder not to fire. If the incontinence bothers the caregivers but not the patient, none of the medications, biofeedback, injections or neuromodulators will be successful. For the frail and very elderly, conservative treatment is best, taking the person to the bathroom on a schedule rather than when the bladder is full. And many people in this situation are best treated with absorbent garments.
Have a conversation with your care provider about your symptoms. Many options to improve your symptoms can be tailored to your specific situation.
— Deborah Lightner, M.D., Urology, Mayo Clinic, Rochester, Minn.