Pudendal nerve injury in men with fecal incontinence after radiotherapy for prostate cancer

Abstract

Background. The precise etiology of fecal incontinence (FI), which occurs frequently following external beam radiotherapy (EBRT) for prostate carcinoma is unknown. It is possibly related to pelvic nerve injury. The aim of this study was to assess the incidence of pudendal nerve dysfunction in men with FI after EBRT for prostate cancer compared to men with FI but no history of EBRT. Material and methods. Data were evaluated from 74 men with intact anal sphincters on endo-anal ultrasound (17 post-EBRT) who had been investigated for FI at a tertiary center. Wexner incontinence scores, pudendal nerve function, anorectal manometry, and rectal sensitivity were compared between the two patient groups. Results. Post-radiotherapy patients were older (77 Ϯ 6 vs. 62 Ϯ 17 years, p Ͻ 0.005) and had worse incontinence than those with no history of radiotherapy (Wexner score; 13 Ϯ 3 vs. 8 Ϯ 4; p Ͻ 0.005). Bilateral pudendal nerve terminal motor latency (PNTML) was abnormal in 87% of radiotherapy versus 22% of non-radiotherapy patients (p Ͻ 0.001) and the signifi cant difference persisted even after correction for age differences. Anal sphincter pressures and rectal sensitivity for both groups were similar. Conclusion. There is a markedly higher incidence of pudendal nerve dysfunction in men with FI after EBRT for prostate cancer compared with men with FI from other etiologies. The increased severity of incontinence in radiotherapy patients is not matched by alterations in either anal sphincter pressures or rectal sensitivity compared to FI in non-ERBT patients.

Pudendal nerve injury impairs anorectal function and health related quality of life measures ≥2 years after 3D conformal radiotherapy for prostate cancer

“…Latency was defined as the time between the stimulation of the pudendal nerve at the level of the ischial spine (the electrical pulse being recorded as a stimulus artifact) and commencement of depolarization of the anal sphincter [15]. A lack of pudendal nerve response was defined as no sphincter contraction on EMG recording in response to stimulus [11].…”

“…Organs at risk such as the rectum and anal canal were contoured as solid organs, the latter from the anal verge to the anorectal junction just below the pubo-rectalis sling around the posterior wall of the rectum [11]. The pudendal nerve from its entry in the pelvis through the sciatic notch and its exit in the perineum through the ischial spine was also contoured from the CT planning scans [11].…”

“…The median and range of the minimum (Dmin), the maximum (Dmax) and the mean (Dmean) doses of the rectum, anal canal and pudendal nerve and the % of each OAR receiving !40% (V 40 Gy) and !60% (V 60 Gy) of the prescribed EBRT doses to the prostate were derived from available CT planning data of 18 patients [11].…”

“…Our recent data suggest pudendal nerve dysfunction is important in the pathogenesis of FI 3-15 years after EBRT for prostate carcinoma [11]. However, in that study only three of the 17 patients examined were treated with 3D-CRT and radiation dose volume data of organs at risk (OAR) were based on modeling of available CT data only.…”

Contouring pudendal nerves

“…He continues to provide cutting-edge knowledge; the enclosed article shows a way to move forward. Treating the pudendal nerves as risk organs during dose planning and implementing dose constraints will decrease the occurrence and severity of the fecal-leakage syndrome in survivors who have received irradiation for a cancer in the pelvic cavity [2,3]. The fecal-leakage syndrome increases with time to follow-up and must be considered as life-long [4].…”