Actress/comedienne Whoopi Goldberg uses a light approach toward the topic of urinary incontinence (UI) in her ads for urine leakage pads; however, millions of women find nothing funny about their experience with this problem. Although UI can be a minor annoyance, consisting of occasional slight leakage of urine, for some women, it represents a much more bothersome problem. The author discusses the role of sacral neuromodulation in treating UI and overactive bladder.

The term urinary incontinence (UI) is sometimes used interchangeably with overactive bladder (OAB), but the definitions are slightly different. The most common types of UI are stress, urge, and mixed. Stress incontinence is the involuntary loss of urine during effort or exertion (eg, lifting, laughing, brisk walking) or when sneezing or coughing. A woman with urge incontinence experiences a sudden feeling of bladder fullness or spasm and a compelling desire to urinate that is difficult to postpone.

This feeling occurs immediately before or during an involuntary loss of urine. As the name suggests, mixed incontinence has features of both stress and urge incontinence.^1,2 As defined by the International Continence Society, OAB is a syndrome characterized by urinary urgency, with or without incontinence; increased frequency and nocturia are usually present.³

Prevalence and Costs of UI/OAB in Women

Urinary incontinence is a common problem in women. Estimates of prevalence vary, depending on the source of the statistics. Data on UI in 2875 adult women from the National Health and Nutrition Examination Survey 2001–2002 showed the overall prevalence of stress UI, urge UI, mixed UI, and any UI to be 23.7%, 9.9%, 14.5%, and 49.2%, respectively.⁴ These estimates may be low because fewer than half of women suffering from UI are diagnosed and seek treatment. For example, a survey of 875 women aged 25-80 years without a previous genitourinary diagnosis who were enrolled in Kaiser Permanente Northwest, combined with a retrospective chart review of those who reported moderate or severe UI, found the prevalence of undiagnosed UI to have been 53% in the preceding year and 39% in the preceding week.⁵ Coyne et al⁶ surveyed Internet-based panel members to identify the prevalence of OAB in the United States. In a sample of 10,584 female respondents aged 40-94 years, OAB symptoms occurred “sometimes” in 43.1% and “often” in 32.6%. Of women who often had OAB symptoms, 73.0% were bothered “somewhat” and 47.1% were bothered “quite a bit” by them.⁶

Data from a population-based, cross-sectional Internet survey were used to examine the impact of OAB symptoms on work productivity in persons aged 40-65 years.⁷ In the group of 2820 women who met the age criterion, 39.9% had incontinent OAB, 18.5% had continent OAB, and 41.6% had no/minimal lower urinary tract symptoms. Mean urinary-specific work impairment scores were highest for women with incontinent OAB (12.6%), followed by continent OAB (10.8%). When asked if they always worried about interrupting meetings with frequent bathroom trips, 36.4% of women with incontinent OAB were completely/somewhat in agreement.

A population-based survey of US community-dwelling adults found that 18.6% (42.2 million) “often” and 28.7% (65.1 million) “sometimes” experienced OAB symptoms.⁸ Annual costs for women “often” and “sometimes” experiencing OAB were $18.8 billion and $26.5 billion, respectively; costs were higher for women than for men. UI has other costs in that it has been associated with increased social isolation, falls, fractures, and admission to long-term care facilities.¹

Risk Factors for UI

In a recent review article, Goode et al1 summarized the major risk factors for UI in women. Prevalence of UI increases with age until about age 50, stabilizes until about age 65, and then again increases with age. Prevalence of stress incontinence is higher in whites than in African Americans or Asians. The risk for UI increases with vaginal delivery, greater maternal age, and higher fetal weight. In one study, each 5-unit increase in body mass index increased the risk for daily UI by as much as 60%;⁹ UI is improved by even small weight reduction.¹

Sacral Neuromodulation in the Treatment of UI/OAB

Therapies for UI/OAB include behavioral treatment (eg, pelvic floor muscle training and exercise, behavioral training for stress and urge incontinence and related symptoms, behavioral lifestyle changes), medication (eg, antimuscarinic medications), and other approaches such as pessaries (if prolapse occurs), percutaneous tibial nerve stimulation, botulinum toxin, a midurethral sling, and sacral neuromodulation (SNM).¹ This article focuses on the last of these options—SNM. Although the exact mechanism of action of SNM is unknown, Baxter and Kim¹⁰ suggested that this therapy may alter a pathologic imbalance of sacral reflexes that control bladder storage and emptying. The only SNM device approved by the FDA for treatment of urge incontinence, urgency-frequency, and nonobstructive urinary retention, alone or in combination, is InterStim® Therapy by Medtronic (Minneapolis, MN); SNM is not indicated for stress incontinence.¹¹ InterStim Therapy involves a small pacemaker-like implantable pulse generator (IPG) attached by way of a lead extension to an implanted tined quadripolar lead wire that mildly stimulates the S3 sacral nerve root.^1,12

Patient Selection, Test Phase, and Placement—SNM is appropriate for patients who have failed conservative treatments or who cannot tolerate them. For example, some patients are unable to use anticholinergic drugs because of the associated effects of dry mouth, constipation, dry eyes, memory loss, and/or heart palpitations.¹² Preliminary testing allows selection of patients most likely to be treated successfully with SNM. Percutaneous/peripheral nerve evaluation (PNE), an office-based procedure, allows practitioners to assess the clinical efficacy of stimulating the sacral nerves prior to full implantation of an SNM device. Placement of a temporary monopolar lead wire allows a patient to ascertain the effect of using an external pulse generator (EPG) to stimulate the sacral nerve over 3-7 days;^10,12,13 like a pager, the EPG can be attached to a belt. A PNE test result is positive when symptoms improve at least 50% over baseline.¹² The temporary lead is removed at the end of the PNE.

The staged-implant test differs from the PNE in that it uses a percutaneous permanent tined quadripolar lead wire, which improves fixation of the leads and response to the test. The lead, which is placed under intravenous sedation or local or general anesthesia in an operating room (OR), can later be converted to the permanent stimulation system. This approach has the advantage over PNE of avoiding differences in lead placement.¹³ Based on a literature review, Baxter and Kim¹⁰ found that IPG implantation rates approach 40%-50% with PNE and 70%-90% with the staged-implant test.

If the PNE or staged-implant test has been successful, a surgical procedure is performed in an OR with the patient under anesthesia. When PNE is used, fluoroscopy is necessary to place the permanent lead in the same location as the temporary wire. The lead is tunneled deeply through subcutaneous fat and attached to the  IPG, which is buried in a deep subcutaneous pocket in the upper buttock. If the staged-implant test was used, the remaining procedure is much simpler. The previous incision where the temporary connector was placed is opened, the permanent IPG is connected to the lead, and the IPG is buried as previously described.¹²

Clinical Efficacy of SNM—Numerous studies have evaluated the efficacy of SNM using InterStim Therapy for urge incontinence, urgency-frequency, and nonobstructive urinary retention. Janknegt et al¹⁴ evaluated the long-term (12-60 months) efficacy of SNM for refractory urge incontinence. Following a successful PNE test, 96 patients (85 women) were treated with SNM therapy. After an average of 30.8 months, there were significant reductions from baseline in the daily frequency and severity of leaking episodes and the number of absorbent pads/diapers replaced because of leaking (P <.0001 for all measures).

Jonas et al¹⁵ evaluated SNM in 177 patients with urinary retention refractory to standard therapy. A greater than 50% improvement in baseline voiding symptoms during a 3- to 7-day PNE test qualified 68 patients for surgical implantation of a SNM system: 37 were randomly assigned to treatment and 31 to a control group with implantation delayed for 6 months. Compared with the control group, the SNM group experienced statistically and clinically significant reductions in catheter volume per catheterization (P <.0001). Among patients in the active treatment group, 69% eliminated catheterization at 6 months and an additional 14% had a ≥50% reduction in catheter volume per catheterization. Therefore, successful results were achieved in 83% of the implant group versus 9% of the control group at 6 months.

A 5-year prospective multicenter trial evaluated the long-term safety and efficacy of SNM in patients with refractory urge incontinence, urgency-frequency, and retention.¹⁶ Of the 152 patients who underwent SNM therapy, the vast majority of whom were women, 96 had urge incontinence, 25 had urgency-frequency, and 31 had retention. At 5 years post-implantation, all groups had experienced statistically significant improvements—that is, those with urge incontinence had a decrease in the mean number of leaking episodes/day, those with urgency-frequency had decreases in mean voids/day and the mean volume per void, and those with retention had a lower mean volume per catheterizations and fewer catheterizations (P <.001). In addition, 68% of patients with urge incontinence, 56% with urgency-frequency, and 71% with retention had successful outcomes.

Adverse Events—Adverse events reported in various trials of SNM therapy included pain at the implant sites, new pain, lead migration, infection, technical or device problems, adverse changes in bowel or voiding function, and undesirable stimulation or sensations, including jolting or shock sensations.¹¹ Rates of adverse events reported in the recent literature are between 11% and 22%.¹⁶

Patient Satisfaction—A survey of 49 patients (46 women and 3 men) about their satisfaction in the 12–52 months following SNM found that 79.6% of respondents said they would choose SNM therapy if they had to do it all over again, and 83.7% were satisfied.¹⁷ Of the 41 satisfied patients, 36.6% were “somewhat better” and 63.4% were “much better.”

New Indication

In April 2011, the US Food and Drug Administration approved SNM for the treatment of chronic fecal incontinence (FI) in patients who have failed or are not candidates for more conservative treatments. According to data from the National Health and Nutrition Examination Survey 2005-2006, the estimated prevalence of FI in US adults is 8.3%.¹⁸ The prevalence may actually be higher; a study including 1707 patients in a health maintenance organization found that 36.2% reported FI, but only 2.7% had a medical diagnosis.19 In a recent multi-site study, 83% of 120 patients (110 women) who underwent chronic SNM implantation achieved therapeutic success (P <.0001), and 41% achieved total continence.²⁰

Conclusion

Sacral neuromodulation is an effective treatment for many women with urge incontinence, urgency-frequency, nonobstructive urinary retention, and now fecal incontinence who are refractory to standard therapy. This approach provides an effective option that nurse practitioners can offer patients who have failed conservative therapies for these conditions.

Saundra Sturdy Seidel is a certified urology clinical nurse specialist at Urologic Specialists of Oklahoma, Inc., in Tulsa. She reports that she serves as a consultant, educator, and course instructor for Medtronic and as a consultant and speaker for Ortho-McNeil.

References

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