What is neurogenic bladder?
Neurogenic bladder is a condition in which the bladder loses its normal storage or emptying function. There are two general patterns of neurogenic bladder dysfunction. The first is a large volume paralyzed bladder that does not empty well. The second is a very small, tight bladder that is spastic, which leads to high pressures within the bladder. Both patterns can lead to incontinence (urinary leakage, urinary tract infections and kidney damage but kidney damage. The high pressures caused by a contracted bladder carry a higher risk of kidney damage. The function of the urinary sphincter can also be affected. The sphincter is the valve that helps us hold our urine. The sphincter can be weak, leading to urinary leakage or it can be spastic and unable to relax, causing some patients to be dependent on catheterizing themselves in order to empty the bladder.
What causes neurogenic bladder?
Anything that damages the nerves to the bladder can result in neurogenic bladder. This includes spinal cord injury from trauma or birth defects of the spinal cord such as spina bifida. There are many of neurologic diseases that can lead to neurogenic bladder including multiple sclerosis, transverse myelitis, cerebral palsy, diabetes, peripheral neuropathy, head injury, vertebral disk herniation, and stroke.
How is neurogenic bladder diagnosed?
A thorough discussion with the patients and a careful physical exam can reveal much about the cause of urinary symptoms. However, additional testing is often required. One of the most helpful tests in the evaluation of neurogenic bladder is called a urodynamic test. Urodynamic testing is also called a cystometrogram (CMG). In this test a very small catheter is passed into the bladder and another catheter is placed into the rectum. The bladder is filled and several measures of the bladder and sphincter function can be determined. These measures can include the cause of incontinence, the capacity of the bladder, and the pressures in the bladder during bladder contraction as well as during filling of the bladder. This test allows the urologist to tailor treatments to the individual patient, depending upon factors like the cause of incontinence and the capacity of the bladder. It also identifies patients with dangerous pressures within their bladder that might lead to progressive damage to the kidneys and kidney failure.
What are some of the treatments for neurogenic bladder?
Because patients with neurogenic bladder frequently have difficulty emptying their bladder, many require a catheter to do so. Intermittent catheterization specifically means inserting a catheter each time one needs to empty and then removing it after. It makes perfect sense that someone who has a paralyzed (flaccid) bladder would need help emptying his or her bladder. It is not so obvious why someone with a spastic bladder and urinary incontinence would need to catheterize to empty. In the latter case, we aim to reduce the number and intensity of bladder spasms and incontinence episodes using medicines or surgery (see below). Although these treatments help with the leakage symptoms they can make it more difficult to empty. Therefore, these treatments are often combined with catheterization, allowing a patient to be dry and to empty on a more convenient schedule.
The advantages of intermittent (or “in and out” catheterization) over wearing a catheter 24 hours a day (a.k.a. indwelling catheter) are several. First, intermittent catheter allows a person to not have to wear a catheter all the time. Second, infection risk is lower with intermittent catheterization. Third, intermittent catheterization puts the bladder through its normal cycle of filling an emptying which promotes bladder health, whereas wearing a catheter all the time causes the bladder to shrivel up from disuse over time. Finally, bladder cancer, bladder stones and urethral erosion are all consequences of wearing a catheter all the time.
Intermittent catheterization is done by the patient or his/her caregiver. It is not a sterile process. Some use a new catheter each time whereas others wash the catheters and re-use them for a week or more. Catheters are covered by insurance.
Often the first line therapy for patients that have urgency of urination, urinary frequency and leakage from neurogenic bladder is anti-cholinergic medicines. These medicines act to relax the bladder and decrease leakage and urgency of urination from bladder spasms or overactivity. Anti-cholinergic medicines are notorious for causing side effects and often patients need to change from one medicine to another to find one that is tolerated well. Treatment with anti-cholinergic medicines may be all that is required for patients that do not have severely contracted bladders with high pressures in the bladder.
Botulinum toxin injection (Botox)
Botulinum toxin is a drug that is used to paralyze the bladder muscle. This drug has been used in many applications and recently has been used for overactive bladder and neurogenic bladders. The medicine is injected into the muscle of the bladder in a scope procedure done in clinic or the operating room. By calming the muscle down, botulinum toxin can decrease the amount of leakage from bladder spasms and decrease dangerous pressures in the bladder. Unfortunately, the medicine only lasts between 6-9 months and then must be injected again into the bladder. The bladder muscle can become completely paralyzed and unable to empty on its own. This is temporary and generally not a concern for people with neurogenic bladder in whom our goal is to completely paralyze the bladder and place them on intermittent catheterization (see above). Botulinum toxin can also be used to treat patients with overactive sphincters and is injected at the level of the sphincter to allow unobstructed passage of urine.
When the bladder is severely contracted and has pressures that may lead to kidney failure, surgery to expand the bladder volume is often the best method of treatment. This surgery is known as bladder augmentation. In this surgery, a patch of bowel is brought down to the bladder and used to dramatically increase the volume of the bladder. This eliminates problems with bladder spasms and urinary incontinence and creates a large capacity low-pressure reservoir for urine. Think of it like a large dome added to a building where the bladder is the building. Patients need to perform intermittent catheterization to drain these bladders via the urethra. If patients are unable to catheterize the urethra due to scarring, pain or difficulty in localizing the urethra because they are in a wheelchair or for other reasons, then a small caliber tube of bowel can be created for catheterization that comes out to the belly button or the lower abdomen. This bowel tube is called a Monti tube or a Mitrofanoff tube. This is like a new urethra and like the urethra it has a valve where it enters the bladder. When successful, it should not leak urine and the valve can only be opened by passing a catheter through the tube into the bladder. Usually this tube is created at the time of bladder augmentation. Patients catheterize this small stoma to drain the bladder 4-6 times per day. The bladder capacity after augmentation is usually about 500 ml.
In some cases the bladder cannot be saved with augmentation surgery. Some bladders are so contracted (or shriveled up) that augmentation of their volume is not practical. Also other patients may have problems like fistula out of the bladder, tumors in the bladder or radiation damage that is so severe that the bladder is not suitable to be used for reconstruction. In these cases the bladder needs to be bypassed and patients need to undergo urinary diversion. There are many types of urinary diversion that range from creation of a new bladder out of a sphere of bowel to creation of a simple conduit to conduct urine from the kidneys to a bowel stoma at the skin.
What are the goals of treatment for neurogenic bladder?
The goals for the treatment of neurogenic bladder is to eliminate bothersome leakage and create a low-pressure reservoir that will preserve kidney function. In many cases this involves conservative management with medical therapy or the use of botulinum toxin, but in other cases surgery may be indicated.