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91 Recovery of the Rectoanal Inhibitory Reflex After Restorative Proctocolectomy [2003년 2월 DCR] 2011-11-17 3573
 
Does It Correlate With Nocturnal Continence?
 
Naoto Saigusa, M.D., Bruce M. Belin, M.D., Hong-Jo Choi, M.D.,Pascal Gervaz, M.D., Jonathan E. Efron, M.D., Eric G. Weiss, M.D.,Juan J. Nogueras, M.D., Steven D. Wexner, M.D.
 
From the Department of Colorectal Surgery, Cleveland Clinic Florida, Weston, Florida
 
PURPOSE: The rectoanal inhibitory reflex has an important role in fecal sampling and discrimination of rectal contents. The aim of this study was to determine the significance of rectoanal inhibitory reflex after restorative proctocolectomy with ileal pouch-anal anastomosis for mucosal ulcerative colitis.
METHODS: The medical records of 345 patients who underwent ileal pouch-anal anastomosis from
September 1988 to May 1999 were retrospectively reviewed. One hundred patients who underwent double-stapled ileal pouch-anal anastomosis and had anorectal physiology testing within 3 months before surgery as well as after ileostomy closure (mean, 23.1; range, 3–77 months) were analyzed. Anorectal physiology testing included detecting the presence of the rectoanal inhibitory reflex, sensory
threshold volume, and rectal or pouch capacity and compliance. Parameters to determine incontinence included daytime and nocturnal bowel movement frequency, nocturnal spotting, status of continence for solid or liquid stool, gas, use of pads, and lifestyle alteration were surveyed in 62 of the 100 patients at a mean of 3.9 (range, 1–9.1) years to determine the incontinence score.
RESULTS: Whereas the rectoanal inhibitory reflex was noted in 96 (96 percent) patients before surgery, it was found in only 53 (53 percent) after ileostomy closure (P  0.0001). Incontinence status data was available in only 62 of the 100 patients (32 RAIRpositive; 30 RAIR-negative). There were no significant differences between the rectoanal inhibitory reflex–positive and the rectoanal inhibitory reflex–negative groups relative to the interval between surgery and manometry (22 vs. 25 months), postoperative threshold sensation volume (32 vs. 31 ml), postoperative compliance (19 vs12 cm H2O/ml),postoperative capacity (85 vs. 66 ml), daytime/nighttime stool frequency (6.2/2 vs.5.5/1.5), or postoperative incontinence score (3.9 vs. 1.8). However, there were significant differences relative to the incidence of nocturnal soiling (12/30 (40 percent) vs. 23/32 (72 percent), P = 0.0012) favoring the presence of the rectoanal inhibitory reflex.
CONCLUSION: Preservation of the rectoanal inhibitory reflex correlated with a decrease in the incidence of nocturnal soiling after double-stapled ileoanal reservoir construction.
 
The rectoanal inhibitory reflex (RAIR) enables the discrimination of rectal consistency (sampling) using the upper anal canal mucosa with its rich sensory nerve endings. This reflex is based on internal
sphincter function and discrimination by the anal canal mucosa.
Although the internal sphincter is innervated by inhibitory sympathetic nerves traveling from the hypogastric nerve plexus and by excitatory parasympathetic nerves from the pelvic nerve plexus, the RAIR is retained even after total isolation of the rectum from extraneous innervation. Further demonstrating the dependence of the RAIR on the intrinsic nerves, patients with Hirschsprung’s disease and after circumferential myotomy lack this reflex. Although this mechanism is known to have a role in the fine adjustment of anal continence, its physiologic significance after ileal pouch-anal anastomosis (IPAA) remains controversial. This study aimed to determine the functional and physiologic outcome after doublestapled ileal pouch-anal anastomosis (DS-IPAA) to better understand the pertinent physiologic components and their impact on functional outcome.
 
DISCUSSION
Rectal distention initiates the RAIR, stimulating the reflexive relaxation of the internal sphincter. The external sphincter compensates during this event to prevent incontinence; however, there is passage of a miniscule amount of material that is then sensed by the anal transitional zone (ATZ). The RAIR contributes to fine fecal continence by sampling fecal material within the ATZ. Despite the insensate nature of the rectal mucosa, rectal distention is detected by the proprioceptors of the levator, puborectalis,and anal sphincter muscles, and it is transmitted via afferent fibers from the pelvic nerves that contribute to the sacral spinal cord. In contrast, the anal mucosa is exquisitely sensitive, allowing for the differentiation among solid, liquid, and gas rectal contents via the inferior rectal branch of the pudendal nerve. Whereas the ATZ provides this discriminatory information, the funnel-shaped lower rectum acts as a reservoir by increasing its volume while maintaining a low pressure. This reflex can be appreciated during manometry as a significant dip in the resting pressure curve on rapid injection of air into a rectal balloon. Although the RAIR does not play an essential role in continence, its absence may subjectively manifest with symptoms of leakage. Thus, postoperative preservation of the RAIR should confer some functional benefit as compared with its ablation.