Effect of sacral neuromodulation on the rectum

Sacral neuromodulation in the treatment of defecation disorders

A large number of patients present with fecal incontinence due to idiopathic pelvic neuropathy or lesions of pelvic nerves, iatrogenic or secondary to other pelvic diseases or dysfunctions, involving sacral nerves. On the other hand, in many patients, constipation could be related to a peripheral neuropathy impairing normal defecation. Sacral neuromodulation (SNM) has been demonstrated as an effective approach in neuropathic defecation disorders. Its application is usually safe and easy, with a limited rate of complications or adverse events. The surgical procedure is made under local anesthesia. SNM effectiveness can be reliably tested during a short term period (up to 30 days) before the decision for a permanent implant. Results in most series show significant clinical improvement, with reduction in the number of incontinence episodes, decrease of incontinence score and improvement in patients' quality of life. A few reports suggest a potential and interesting application of SNM in constipation. Findings from anorectal manometry and other physiology examinations are not conclusive in order to define SNM mechanisms of actions and suggest that a multifactorial effect "modulates" the deficient neuromuscular system causing the defecation disorders.

Sacral neuromodulation; does it affect colonic transit time in patients with faecal incontinence?

OBJECTIVE

Sacral neuromodulation (SNM) has been a successful treatment in urinary voiding disorders for years. A concomitant effect on bowel function was observed leading to the treatment of faecal incontinence with SNM. In this study we describe the effect of SNM on bowel frequency and (segmental) colonic transit time.

PATIENTS AND METHODS

Fourteen patients with faecal incontinence who qualified for permanent SNM underwent a colon transit study before and one month after permanent implant. Patients completed a three-week bowel habits diary before and during stimulation.

RESULTS

Median incontinence episodes and days per week before SNM were, 8.7 and 4.2, respectively, and both decreased significantly to 0.67 (P = 0001) and 0.5 (P = 0001) during trial screening and to 0.33 (P = 0001) and 0.33 (P = 0001) after permanent implant. The median number of bowel movements per week decreased from 14.7 (6.7-41.7) to 10.0 (3.7-22.7)(P = 0005) during trial screening and to 10.0 (6.0-24.3)(P = 0008) during permanent stimulation. Resting and squeeze pressures did not change significantly during stimulation. Segmental colonic transit time before and during stimulation for right colon, left colon and recto sigmoid were, respectively, 6 (0-25) vs 5 (0-16) hours, 2 (0-29) vs 4 (0-45) hours and 7 (28) vs 8 (0-23) hours. No significant changes were found in both segmental and total colonic transit time; 17 (1-65) vs 25 (0-67) hours.

CONCLUSION

SNM in patients with fecal incontinence led to a significant decrease of bowel movements however (segmental) colonic transit time was not influenced.

Low rectal volumes in patients suffering from fecal incontinence: what does it mean?

BACKGROUND

Rectal perception and adaptation to distension are widely heterogeneous in subjects with faecal incontinence.

AIM

To quantify rectal physiology in patients with incontinence and low maximum rectal volume, according to AGA guidelines on anorectal testing techniques.

PATIENTS AND METHODS

148 patients (12 men, 136 female) with incontinence to liquid and/or solid stools were investigated. Distending isobaric procedures were carried out using an electronic barostat in order to analyse perception and adaptation of the rectum.

RESULTS

Pain during isovolumic rectal distension at a level of 100 mL or less was experienced in 21 subjects (14.2%). As defined by isobaric distensions, incontinent patients with low MTV had more frequently a hypocompliant rectum (62%) when compared with those with higher MTV (31%, P = 0.046). Perception scores tended to be higher at each step of distending rectal pressure: incontinent patients with low MTV had more frequently a hypersensitive rectum (48%) when compared with those with normal or high MTV (24%, P = 0.035). Only four of 21 incontinent subjects with low MTV had an isolated hypersensitive rectum.

CONCLUSION

Both sensitivity and compliance are altered in patients with low MTV. A more extensive study of the role of sensory and compliance aspects of subjects with incontinence is warranted.