Role of Pudendal Sensory Nerve in Patients with or without Fecal Incontinence after Low Anterior Resection for Lower Rectal Cancer

To clarify the pudendal sensory nerve(PSN)play in preventing fecal incontinence(FI)after low anterior resection(LAR) for lower rectal cancer, the PSN function was studied at 6 months after LAR. A total of 36 patients aged 42.0 to 79.0 years (23 males and 13 females with a mean age of 62.0 years)who underwent LAR for laparoscopic radical cystectomy(LRC) were enrolled in the present study. Based on postoperative F1, these patients were divided into 2 groups[group A; patients with FI(n=12), group B; patients without FI(continence, n=24)]. These were compared with group C(n=32, control subjects, 18 males and 14 females aged 40.0 to 76.0 years with a mean age of 61.8 years). Anal mucosal electric sensitivity (AMES)threshold was measured [at the upper 1 cm oral side from dentate line(DL); a, DL; b, and lower zones 1 cm anal side from DL; c]. FI after LAR was also evaluated by the Wexner score(WS). All patients were pathological Stage Ⅰ(25 patients: T1, N0, M0; 11 patients: T2, N0, M0). Group A had a significantly larger proportion of males than group B(p< 0.05). The distance of anastomosis from anal verge(DAAV)in group A(2.4±1.8 cm)was significantly shorter than in group B(4.4±0.9 cm)(p<0.001). WS from 6 to 10 comprised 25.0% of group A, 11 to 15 comprised 50.0%, and 16 to 20 comprised 25.0%. All patients in group A(WS; 8 or more)were incontinent. In contrast, all patients in group B(WS; 0) and C(WS; 0)were continent. Patients in pre-operative defecation(WS; 0)were also continent. On the AMES(a, b, c), sensitivity of patients in group A(6.4±1.1, 5.1±0.5, 4.9±0.6 mA)was significantly higher than in groups B(2.6±0.5, 2.4 ±0.4, 2.5±0.6 mA)and C(2.3±0.4, 2.1±0.4, 2.3±0.5 mA)at all zones(p<0.001). FI after LAR with a short DAAV, especially male, may be PSN dysfunction due to operative damage of PSN.