Selecting patients for sacral nerve stimulation
Section snippets
History
The patient is a middle-aged woman who complained of urinary frequency of up to 20 voids in 24 hours. The stream was often inefficient, with small voided volumes, and a sensation of incomplete emptying. The degree of urgency was out of proportion to the voided volume, but she could hold it if she had to. She had rare episodes of incontinence. The symptoms were present for several years, and were not helped by various anticholinergic agents. She felt as though her life revolved around the
Indications for sacral nerve stimulation therapy
The US Food and Drug Administration (FDA) approved SNS for intractable urge incontinence in 1997, and for urgency-frequency and nonobstructive urinary retention in 1999. Later, the labeling was changed to include “overactive bladder” as an appropriate diagnostic category. Patients in these groups are appropriate for SNS when they have chronic symptoms that significantly affect quality of life, and conservative treatments have been unsuccessful [1], [2].
Clinical evaluation of voiding dysfunction
The tools necessary for proper evaluation of patients who have voiding dysfunction are readily available. They involve a careful history, physical examination, routine tests such as urinalysis and urine culture, simple diagnostic tests such as pelvic ultrasound and cystoscopy, and the use of diaries to objectify appropriate voiding variables. A urodynamic examination to identify abnormal pelvic floor muscle function is also of great help (Fig. 3).
Summary
Patient selection for SNS remains empiric. A key is to think of voiding dysfunctions in terms of voiding behaviors and pelvic floor muscle function, not organ-based labels. Patients who have intractable urinary frequency, urgency, urge incontinence, or idiopathic urinary retention should be considered as prime candidates. Evidence of high-tone pelvic floor muscle dysfunction also may be demonstrated on routine physical examination, as well as diagnostic studies such as pelvic-floor EMG. A
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