In a normal functioning bladder, the nervous system sends signals between the brain and the bladder. This allows the bladder to fill to capacity and the brain to know when it is time to urinate. When the brain receives the message that the bladder is full, the detrusor muscle of the bladder then contracts. This contraction forces urine out of the bladder and the urethral sphincter relaxes, allowing urination to occur.
With uncomplicated OAB, dysfunction of the nerves involved in this process can result in low bladder capacity and/or premature bladder muscle contractions. Weak pelvic floor muscles and/or a weak urethral sphincter can also contribute to urine loss in patients with OAB.
There are many other causes of OAB such as cystocele, prior sling surgery and incomplete bladder emptying. Neurologic disorders such as a prior stroke or multiple sclerosis can also cause OAB.
Proper treatment of overactive bladder requires evaluation to find the cause of symptoms. Evaluation may include physical exam, urine analysis, urodynamics and cystoscopy. During urodynamics, a tiny catheter is used to fill the bladder and takes measurements of the bladder and its muscle activity. During cystoscopy, the inside of the bladder and urethra are evaluated for abnormalities.
Behavior Therapy – Behavioral therapies are designed uniquely for each patient depending on her drinking and voiding habits and her specific OAB symptoms. If successful in controlling symptoms, no further treatment is needed.
Here are links to specific Behavioral Therapies for control of various OAB symptoms.
Medications – Medications are used when Behavioral Therapy alone does not adequately control symptoms.
Anticholinergics such as Myrbetriq work by binding to cholinergic receptors in the bladder, inhibiting involuntary bladder contractions. These cholinergic receptors also exist in other organs, and binding to them thus causes other side effects. Side effects are at times difficult to manage. Myrbetriq activates the beta-3 adrenergic receptors of the bladder and directly relaxes the bladder during filling. Most patients tolerate Myrbetriq as side effects are minimal.