New Pharmacologic and Minimally Invasive Therapies for the Overactive Bladder

Michael Franks, MD, Emmanuel Chartier-Kastler, MD, Michael B. Chancellor, MD

In This Article

Bladder Function

The management of incontinence is varied and depends on the exact cause. The primary causes include ineffective sphincter function, or stress incontinence; detrusor hypersensitivity with urgency, or urge incontinence; and obstruction with possible overflow incontinence.

The primary functions of the bladder and lower urinary tract are the storage and timely expulsion of urine, with maintenance of a barrier between the urine and plasma. The bladder is capable of accomplishing its storage function by painlessly accepting large volumes of urine with little or no change in intravesical pressure. The sphincters of the bladder neck (internal sphincter) and the striated muscle urethral sphincter (external sphincter) maintain continence. Micturition is a finely tuned, coordinated dance characterized by opening of the sphincters and contraction of the detrusor.

The unstable detrusor is one that is shown objectively to contract, either spontaneously or upon provocation, during the filling phase while the patient is attempting to inhibit micturition.[2] The generic term for involuntary detrusor contractions is detrusor overactivity. When involuntary detrusor contractions are caused by a neurologic abnormality, the condition is called detrusor hyperreflexia. In the absence of a neurologic lesion, the condition is termed detrusor instability.[3] When clinical information is insufficient for this distinction to be made, such as in the frail elderly, the term detrusor overactivity is preferred.

From a clinical perspective, the etiology of detrusor overactivity is diverse (Table 1). In certain neurologic disorders, the cause-effect relationship is obvious and well studied.[4] In others, such as inflammation and infection, the relationship is mere conjecture. Other causes of detrusor instability include urethral and bladder trauma, bladder outlet obstruction, aging, and anxiety neurosis.[5] Because understanding of the pathophysiology of the unstable bladder is incomplete, attempts to improve the management of this condition remain elusive.[6]


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