Overview

Sexual dysfunction is a long-term complication of rectal cancer treatment, affecting both men and women. Sexual dysfunction is described as symptoms that may include the inability to achieve orgasm, retrograde ejaculation erectile dysfunction, decreased libido, dyspareunia, and diminished vaginal lubrication.[1] Autonomic nerve injuries during rectal resection are major contributing factors that can cause urinary and sexual dysfunction. After rectal resection, erectile dysfunction is often the most common autonomic nerve-related complication in men while dyspareunia and decreased vaginal lubrication are the most common complications in women.[2]

Both sympathetic and parasympathetic nerve injury may occur during total mesorectal excision (TME).[3]

As the sympathetic fibers arise from L1, L2, and L3, they pass through the sympathetic chains to join the preaortic plexus (Figure 1). From this plexus, these fibers continue just dorsal to the inferior mesenteric artery (IMA) as the mesenteric plexus and innervate the upper rectum. The presacral nerves from the hypogastric plexus innervate the lower rectum. On each side of the rectum, the hypogastric nerve carries the sympathetic information from the hypogastric plexus to the pelvic plexus. The pelvic plexus lies laterally at the level of the lower third of the rectum, adjacent to the lateral stalks.[4]

Figure 1. Autonomic Nerves

The superior hypogastric nerves arise from the T12–L2 spinal level to deliver the sympathetic innervation to the pelvic viscera, as shown in Figure 2.[5]

Figure 2. Superior Hypogastric Plexus

Arrows are on hypogastric nerves; box is on the ureter, and star is on the inferior mesenteric artery.

There are four operative sites at particular risk for nerve injury.[3] Figure 3 shows an illustration of some of the sites discussed below.

1. Origin of the IMA. Injury to the superior hypogastric sympathetic nerve plexus above the sacral promontory and near the IMA origin causes ejaculatory dysfunction, which often manifests as retrograde ejaculation. This complication can be avoided by 1) preserving the sympathetic superior hypogastric plexus nerve fibers near the origin of the IMA as well as the more distal hypogastric nerve trunks, 2) minimizing traction on the IMA origin, and 3) leaving a 1-cm pedicle at the root of the IMA during division (as show above in Figure 2).
2. Posterior rectal TME dissection. TME starts at the sacral promontory where the left and right hypogastric nerves may be visualized coursing along the sacral concavity. These nerves are sympathetic. Identification of these nerves while dissecting in the correct plane between the fascia propria of the rectum and presacral fascia allows nerve preservation.[6]
3. Lateral rectal TME dissection. Excessive traction and/or wide lateral dissection at the level of the lateral stalks may cause injury to the inferior hypogastric plexus, which contains sympathetic fibers from the hypogastric nerves and parasympathetic fibers from the sacral nerves (S2, S3, and S4). Thermal injury may occur with electrocautery. Nerve injuries of this type can be minimized by performing TME in the proper plane of dissection.[7]
   
4. Anterior rectal TME dissection. The integrity of Denonvilliers’ fascia, invested by the periprostatic plexus, should be preserved during dissection between the rectum and the prostate and seminal vesicles; the exception to this approach is when an extended radial margin of resection is necessary to achieve an R0 resection. Injury to the parasympathetic nerve supply in the nervi erigentes (pelvic splanchnic nerves) at this location is a common autonomic TME injury and may result in erectile dysfunction and dyspareunia.[8] Prior to the advent of TME, postoperative erectile dysfunction and retrograde ejaculation rates were observed in 25%–75% of patients undergoing rectal cancer surgery cases. However, careful adherence to TME mesorectal dissection planes has decreased this rate to 10%–29%.[9]

Key to avoidance of the parasympathetic and sympathetic nerves is understanding their pathways and relationship with other anatomical structures (Figure 3).[3][9]

Figure 3. Distribution of Sympathetic and Parasympathetic Nerves in the Pelvis

Used with permission of Springer-Verlag, from Runkel N, Reiser H. Nerve-oriented mesorectal excision (NOME): autonomic nerves as landmarks for laparoscopic rectal resection. Int J Colorectal Dis. 2013;28(10):1367–75; permission conveyed through Copyright Clearance Center, Inc.

Adhering to mesorectal dissection planes and identifying superior hypogastric plexus nerve fibers, left and right hypogastric nerves in the sacral concavity, and inferior hypogastric plexus nerves during lateral and anterior dissection are key to lowering the incidence of sexual dysfunction after TME. Studies evaluating the impact of neoadjuvant radiotherapy on sexual dysfunction are not conclusive, and it is uncommon for radiotherapy to be considered the only causative factor. More data may become available in future studies of sexual dysfunction in patients who have a complete clinical response after neoadjuvant therapy and who undergo nonoperative surveillance instead of TME.[3] Other risks factors for sexual dysfunction are thought to include abdominoperineal resection (APR), age over 65 years, and pelvic sepsis from postoperative anastomotic leak or abscess.[10]

Management of postoperative sexual function is multifactorial. Pilot studies of patients with neurogenic impotence after prostatectomy have shown that multidisciplinary treatment, including sexual counseling and behavioral therapy, improve symptoms within 6–12 months.[11] Following proctectomy, pharmacologic treatment with phosphodiesterase inhibitors, such as oral sildenafil, has been shown to improve sexual function in 80% of men compared with 17% of those receiving placebo.[2] Other options include intracavernous and intraurethral injections and vacuum-constriction devices.[12] Counseling can help reassure patients and their partners that there are options to improve sexual dysfunction that may result from their treatment of their rectal cancer.[13] In the event of failure of behavioral and pharmacologic therapies, placement of a penile prosthesis can be effective.[14]

The possibility of sexual dysfunction as a complication of rectal cancer treatment should be part of the pretreatment conversation with the patient. More than 50% of patients feel they do not receive satisfactory preoperative education relevant to sexual dysfunction.[3] Only 9% of women are told of the possibility of sexual dysfunction after TME, and less than 10% of men and women receive specialty consultation when sexual dysfunction occurs after TME.[3]