BERKELEY, CA (UroToday.com) - Overactive bladder (OAB) is a disturbance of bladder filling/storage and has been defined by the International Continence Society as “a symptom syndrome consisting of urgency with or without urge urinary incontinence, often associated with urinary frequency and nocturia.”
This problem often remains undetected and undertreated, despite its substantial impact on a woman’s quality of life.
The purpose of the lower urinary tract (LUT) is to store and release urine. This process is dependent on coordination of the activity of smooth and striated muscles in the bladder, urethra, and pelvic floor. Voiding is controlled by a complex interplay between the central nervous system (CNS) and peripheral autonomic, somatic, and sensory afferent innervations of the LUT, bladder, and urethral sphincter. Interruptions at any point in this pathway can lead to bladder control disorders.
Women with OAB often experience urinary urgency, frequency, and even leakage prior to reaching a toilet. These symptoms interfere with work, activities of daily life, intimacy, and sexual function.
Most women with urinary urgency and frequency can be evaluated and the diagnosis of OAB made utilizing standardized questionnaires, bladder diaries, a thorough history and physical examination, urinalysis, post-void residual and simple cystometry. Multi-channel urodynamics are usually reserved for complex presentations.
Once the diagnosis of OAB has been made, the combination of dietary and lifestyle modification, bladder training, pelvic floor muscle training (PFMT), and biofeedback should be recommended as the initial intervention for OAB. Behavioral therapy requires the active participation of motivated patients and a practitioner well-trained in behavioral therapy. Regular adherence and long-term compliance are needed for effectiveness.
Antimuscarinic (anticholinergic) drugs are considered the “gold standard.” There are at least 10 different antimuscarinic compounds licensed for use in OAB. There is little or no evidence to help clinicians choose between particular drugs. Antimuscarinics block, more or less selectively, muscarinic receptors on the detrusor muscle to decrease bladder contractions. Five muscarinic receptor subtypes have been identified and the M3 receptor is responsible for detrusor contractility in the normal bladder. The main difference between antimuscarinic drugs is their affinity for the M3 receptor. This selectivity is responsible for the different side effect profiles of the various drugs, although all have some of the undesirable side effects of dry mouth and constipation.
Neuromodulation devices, such as sacral nerve stimulation and percutaneous stimulation of the peripheral tibial nerve, act to inhibit detrusor contractions. The exact mechanism of action is not well understood but patients with refractory OAB have shown improvement with both therapies.
There are other therapies on the horizon such as beta adrenoreceptor agonists centrally acting drugs. The detrusor muscle contains B2 and B3-adrenoceptors. Both receptors are thought to be involved in detrusor relaxation. There are a number of [beta] 3-adrenoceptor selective agonists being evaluated as potential treatment for OAB.
First-line therapy for OAB should include conservative options such as timed voiding and behavioral modification. Antimuscarinic (anticholinergic) drugs are the cornerstones of pharmacological treatment of OAB. For patients who do not tolerate antimuscarinic (anticholinergic) therapy, sacral nerve stimulation or peripheral nerve stimulation can be considered. Most patients with OAB can be managed with a simple office workup.
Howard A. Shaw, MD, MBA, FACOG as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.