Preamble to Sacral neuromodulation

Key words: sacral nerve stimulation, sacral neuromodulation, pelvic floor dysfunction, voiding dysfunction

Sacral neuromodulation provides a new option for the management of voiding dysfunction. Tanagho and Schmidt first introduced sacral nerve neuromodulation in 1981 (2,3). Tanagho and Schmidt implanted the stimulator to treat voiding disorders like urinary urge incontinence, urgency-frequency, and nonobstructive urinary retention (3). For patients with voiding disorders, this procedure has resulted in significant improvement in urinary frequency, voided volume and pelvic pain (1).
However since then, it has become increasingly popular and the indications for this procedure are growing well beyond just 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 (3).

According to Pettit & colleagues following are the recent findings (3):

1. Fecal incontinence: 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.

2. Interstitial cystitis: Intractable interstitial cystitis is defined as patients that have failed conventional therapy. Historically, the only option remaining was 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.

3. Chronic refractory pelvic pain: 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.

However there is promise in this module of treatment but much of the research is yet to come.

Sacral nerve stimulation in Pelvic floor dysfunction:

Pelvic floor dysfunction is a complex problem that can be refractory to current treatment modalities; even with surgery the out come is unsatisfactory & sub-optimal (4). According to Aboseif & colleagues sacral nerve stimulation is an effective and durable new approach to pelvic floor dysfunction with minimal complications where they recommend a test stimulation as a guide to for patient selection.

Sacral nerve stimulation in anal pain:

Chronic idiopathic anal pain is a common, benign symptom, the etiology of which remains unclear. Traditional treatments are often ineffective (5). Falletto & colleagues found in long-term relief of pain & positive improvement in quality of life in their patients. Many authors believe that SNS must be tried before adopting more aggressive surgical procedures for patients with chronic idiopathic anal pain even in whom pharmacologic and biofeedback treatments have failed to produce effective results.

References:

1. Johnson DN et al; W V Med J. 2003 May-Jun;99(3):111-3.
2. Hassouna M et al; Curr Urol Rep. 2003 Oct;4(5):391-8.
3. Pettit PD et al ; Curr Opin Obstet Gynecol. 2002 Oct;14(5):521-5.
4. Aboseif S et al; Urology. 2002 Jul;60(1):52-6.
5. Falletto E et al ; Dis Colon Rectum. 2009 Mar;52(3):456-62.