Sacral neuromodulation: new applications in the treatment of female pelvic floor dysfunction

The first sacral nerve stimulators implanted by Tanagho and Schmidt (1981) were performed for the indications of urinary urge incontinence, urgency-frequency, and nonobstructive urinary retention. Since that time, observations have been made for benefits beyond voiding disorders. These additional benefits have included re-establishment of pelvic floor muscle awareness, resolution of pelvic floor muscle tension and pain, decrease in vestibulitis and vulvadynia, decrease in bladder pain (interstitial cystitis), and normalization of bowel function.

Therapy for fecal incontinence in patients with a structurally intact sphincter mechanism appears to be very promising. Investigators agree that there is a role for sacral nerve stimulation in patients with urge fecal incontinence that have failed conservative efforts. Objective manovolumetric testing shows an increase in resting pressure, an increase in voluntary contraction pressure, a decrease in rectal volumes which cause first urge, a decrease in rectal volume to initiate first urge to defecate, and an increase in duration of maximum squeeze pressure. Intractable interstitial cystitis is defined as patients that have failed conventional therapy. Historically, the only option remaining was extirpative surgery or diversion. Maher et al. reported on patients with intractable interstitial cystitis who had undergone sacral nerve stimulation. They found that 73% of these patients had a reduction in pelvic pain, daytime frequency, nocturnal urgency and an increase in average voided volumes. The final area of interest concerns refractory pelvic pain. Siegal et al. reported a decrease in severity, number of hours of pain, and improved quality of life measures in patients who underwent transforamenal sacral nerve stimulations. These patients had all failed conventional pain therapy.

While the data are encouraging in these new arenas of pelvic floor disorders, investigators acknowledge the need for multicenter, statistically powered studies to evaluate the validity of these findings.