What are the Causes, Diagnosis and Treatment of Overactive Bladder?
May 27, 2019
Bob, a 53-year-old executive, realized he was waking up two or three times a night to go to the bathroom. During the day, he frequently ran to the men’s room, to avoid embarrassing accidents. Bob was diagnosed with benign prostatic hyperplasia (BPH), an enlarged prostate condition, which was now obstructing the urine flow from his bladder. Initially, his doctor prescribed a medication to relax the prostate, with only minimal success. Further testing confirmed that his prostate enlargement had caused the bladder to become overactive, giving him the frequent urges to urinate. Bob had a prostate procedure to open the obstruction, and the urine flow improved greatly. Still, the frequent urges occurred. Bob’s doctor now prescribed different pills to calm the overactive bladder, but they caused him constipation and a very dry mouth. The doctor then prescribed mirabegron, a new class of drug for overactive bladder. Bob’s frequent urination resolved, he stopped getting up at night to urinate, and best of all, he had no unwanted side effects. With one pill daily, Bob was finally back to normal.
Bob’s story is typical. Thousands of men and women are diagnosed with overactive bladder (OAB) every year. Frequency and urgency of urination usually occurs gradually. People continue to suffer with the symptoms of OAB, because it usually develops later in life and becomes slowly worse over many years.
What is OAB?
The urinary bladder is essentially a storage bag with a muscular coating called the detrusor. OAB is caused by an unwanted contraction of the detrusor muscle. The detrusor is connected to the brain by the nervous system, with many nerves running throughout the pelvis, connecting to the spinal cord, and right up to the brain stem and then the cortex, the “thinking” part of the brain. Through this connection, we are warned about detrusor contractions. Usually our brain is able to communicate to the bladder to “hold on” until we get to a toilet. When OAB becomes very severe, the brain may not be able to overcome the urges, and leakage may occur.
Typically OAB occurs when either the detrusor grows too strong, as in Bob’s story, or when the brain—bladder connection is somehow interrupted. In Bob’s case, the obstruction of the bladder from the enlarged prostate caused the detrusor to grow stronger to push the urine out. As the detrusor grows stronger, it becomes thicker, and less elastic, limiting its ability to hold the same amount of urine it previously held. Because bladder capacity is reduced, there is less time to store urine, and more frequent urges occur. When the urges happen, the strong detrusor contraction may leave little time to find a toilet, resulting in leakage.
The brain—bladder connection is essential to urinary control. Some neurological conditions may cause interference or a loss of this connection at any point along the pathway. What does that mean and how does it happen?
In dementia or multiple sclerosis, the cortex of the brain is affected, and may not be able to suppress urgency signals coming from the detrusor. The same can happen with a stroke or with Parkinson’s disease. With a spinal cord injury, the brain—bladder connection is lost, and the bladder will contract without “permission” from the brain.
People may also develop OAB from an infection, or less commonly, from bladder cancer. It is always very important to get an evaluation from a urologist, a doctor specializing in urinary control problems.
Evaluation of the OAB can include a look inside the bladder (cystoscopy) and a checkup on the motor functionality of the bladder (Urodynamics). Physical causes such as obstruction, stones, or tumor can be assessed. Motor and sensory function will be documented by the Urodynamics test, allowing the urologist to correctly diagnose, and thus, treat the problem.
Treatment of OAB may come in the form of a pill, an injection, or by neurological stimulation. Let us first consider pills. Oral medications for bladder control have been around for decades in the form of “anticholinergics.” These medications, including oxybutynin, work at the level of the bladder muscle (detrusor) to reduce the signals coming from the nerves. The nerves to the bladder send a chemical (acetylcholine) to a receptor on the bladder muscle to tell it to contract. Oxybutynin, and its fellow anticholinergic medications compete for those receptors, and help keep the bladder muscle relaxed. Side effects from this class of medications may occur because many other parts of the body use the same nerve connection for communication. Nerves to the salivary glands, the eyes, and the bowels may become affected, resulting in dry mouth, dry eyes, and constipation. Oxybutynin may also cause confusion, or worsen glaucoma.
A newer pill, mirabegron, works by a different mechanism. It, too, affects the bladder muscle, but it communicates with a different cellular receptor (Beta 3 receptor), which directly relaxes the muscle cell. Best of all, this drug, given at the proper dose, has little effect elsewhere in the body. Because it works by a different mechanism, it can also be given in combination with the anticholinergic medications. In some patients, the mirabegron may worsen high blood pressure. If blood pressure is a concern, periodic monitoring by your doctor is important. Mirabegron is FDA approved, and is safe for both men and women.
Some patients with OAB may benefit from Botox for the bladder. The detrusor can be directly injected by a safe office procedure to give up to six months of detrusor relaxation, and relief from OAB symptoms. Other patients may benefit from neuromodulation of the bladder, which can be achieved with an implantable device (Interstim) or by needle stimulation to the nerve of the ankle (PTNS). These options are best discussed with a urologist.
Overactive bladder (OAB) is a common problem, yet very treatable. If you are suffering from urinary frequency, urgency, incontinence, or waking too many times to urinate, then don’t hesitate to ask your doctor about treatment for OAB.
Please do not hesitate to contact our practice for an appointment. We look forward to treating you.
Wishing you the best in health,
Clifford Gluck M.D. FACS