Bjs2282 1493.1494

Iatrogenic impotence and rectal dissectionI. Lindsey and N. J. McC. MortensenDepartment of Colorectal Surgery, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK(e-mail: lindseyilinz@yahoo.com and resnaith@hotmail.com) Colorectal surgeons are becoming ever more aware of the near the pelvic plexus, and during deep dissection of the details of the surgical anatomy of the rectum and anterior aspect of the rectum away from the seminal vesicles surrounding pelvic structures in the drive to improve not and prostate near the cavernous nerves.
only the oncological but also the functional outcome of Accumulating evidence suggests that most trauma to pelvic surgery. In the past, impotence after proctectomy has parasympathetic nerves occurs during deep anterior dissec- been overattributed to non-surgical factors, such as the tion. First, published impotency rates after abdomino- presence of a stoma or the fear of recurrent cancer. Higher perineal excision are consistently higher than after anterior impotence rates in ileostomists have never been demon- resection for rectal cancer, re¯ecting a deeper rectal strated1 and there is now increasing recognition of the role dissection5. Second, operations for rectal cancer that involve rather than spare the anterior rectal quadrant are Traditionally, subjective assessment methods (interview associated with a higher rate of impotence6. Third, or questionnaire) have been used to explore impotence after impotency rates after close rectal versus mesorectal excision proctectomy, but recent objective evaluation has proved for in¯ammatory bowel disease are the same when a close illuminating. Nocturnal penile tumescence monitoring, rectal dissection is used immediately behind the prostate in assuming that nocturnal erections during rapid eye move- an otherwise mesorectal technique7; this suggests the ment sleep are equivalent to sexually induced erections, importance of the anterior dissection. Finally, in the strongly supports the aetiological role of parasympathetic Singapore trial of laparoscopically assisted versus open nerve injury. Patients with impotence after proctectomy for surgery for rectal cancer, published in this edition of BJS8, rectal cancer or in¯ammatory bowel disease have a impotency rates were tenfold higher after laparoscopically signi®cantly reduced number of tumescent events when assisted surgery, yet ejaculatory and bladder dysfunction monitored for two nights, compared with matched potent were equivalent in the two groups. This indicates that nerve controls2. Intriguingly, the phosphodiesterase type 5 injury takes place distal to the origin of nerves supplying inhibitor sildena®l (Viagra; P®zer, Tadworth, UK) helps motor function to the bladder, distal to the pelvic plexus, i.e.
impotent patients with diminished nocturnal tumescent injury affects the cavernous nerves during anterior dissec- activity (and thus parasympathetic nerve damage) more tion (which is generally the most technically dif®cult point than those with preserved activity2. Sildena®l works by to obtain good retraction and vision during laparoscopic augmenting the vasodilator effect of parasympathetic neural tone on the choke arterioles governing in¯ow to In the authors' opinion, injury to the pelvic plexus is the erectile cavernous chambers of the penis. It requires uncommon unless it is tented up during ligation of the so- the presence of at least some intact and functioning called `lateral ligaments', a technique on the wane with parasympathetic nerve ®bres to exert its effect3, and is declining belief in this anatomical concept9. Urological generally less effective when profound neural injury under- studies have established the anterior cavernous nerves as lies impotence4. This ®nding supports the role of para- central to the development of erectile dysfunction after sympathetic nerve injury and, in particular, suggests that the pelvic surgery10. These small nerves are extremely close neural lesion in postproctectomy impotence is frequently during anterior dissection, yet are not visualized. They arise as branches from two discrete neurovascular bundles that sit Where does this nerve injury take place? It is dif®cult to just anterior to the lateral borders of Denonvilliers' fascia be certain about where most injuries occur, but there are between the rectum and the prostate and seminal vesicles.
four key zones of risk of autonomic nerve damage. The risk Anterior dissection deep in the pelvis can be especially of sympathetic nerve damage occurs in the abdomen during dif®cult, particularly in a male with a bulky tumour, and ligation of the inferior mesenteric artery pedicle, and high in occasionally troublesome bleeding requires diathermy the pelvis during initial posterior rectal dissection adjacent control. The mesorectal plane is also slightly less well to the large hypogastric nerves. Lower down, risk to the de®ned anteriorly than posteriorly. It is not dif®cult to parasympathetic nerves occurs while dissecting laterally imagine how these small nerves may be damaged.
British Journal of Surgery 2002, 89, 1493±1494 1494 Leading article · I. Lindsey and N. J. McC. Mortensen It seems important to de®ne the principal zone of injury so Maximum preservation of the cavernous nerves, when that suitable steps may be taken to prevent postproctectomy possible, is especially important as a result of the advent of impotence. The choice of surgical plane for anterior rectal modern pharmacological agents for impotence that act by dissection is a factor within the surgeon's control; it has an amplifying otherwise suboptimal function in these nerves12.
in¯uence on impotence and should be better de®ned. A consensus has been reached regarding the anatomy of the planes of posterior and lateral rectal dissection (mesorectal plane), but this is not the case anteriorly. What planes are 1 Burnham WR, Lennard-Jones JE, Brooke BN. Sexual available anteriorly; can the surgeon easily differentiate them; problems among married ileostomists. Survey conducted by and which should be used and when? There are three planes, the Ileostomy Association of Great Britain and Ireland. Gut and dissection within them involves resection of none, some, or all of the structures lying between the anterior rectal wall and 2 Lindsey I, Cunningham C, George BD, Mortensen NJMcC.
the prostate and seminal vesicles. The planes are, respectively, Nocturnal penile tumescence is diminished but not ablated in characterized by the anterior mesorectum, the fascia propria of post-proctectomy impotence and explains response to the rectum, and Denonvilliers' fascia.
sildena®l (Viagra). Colorectal Dis 2002; 3(Suppl): 27.
3 Carrier S, Zvara P, Nunes L, Kour NW, Rehman J, Lue TF.
The close rectal dissection plane, immediately on the Regeneration of nitric oxide synthetase-containing nerves after rectal musculature within the mesorectal fat, is not a natural cavernous nerve neurotomy in the rat. J Urol 1995; 153: 1722±7.
anatomical plane. Some will favour this dissection for 4 Quinlan DM, Epstein JI, Carter BS, Walsh PC. Sexual in¯ammatory bowel disease, but it is technically dif®cult function following radical prostatectomy: in¯uence of and is probably required only behind the prostate to preservation of neurovascular bundles. J Urol 1991; 145: minimize impotence7. The mesorectal plane, immediately outside the fascia propria, is an anatomical plane that should 5 Lindsey I, Guy RJ, Warren BF, Mortensen NJMcC. Anatomy be familiar to the colorectal surgeon; it is the standard plane of Denonvilliers' fascia and pelvic nerves, impotence, and used in operations for rectal cancer. Dissection in this plane implications for the colorectal surgeon. Br J Surg 2000; 87: separates the fascia propria of the rectum from Denonvilliers' fascia, which is left intact on the prostate 6 Lindsey I, Kettlewell MGW, George BD, Mortensen NJMcC.
and seminal vesicles and not the anterior surface of the Erectile dysfunction after rectal cancer surgery: anterior rectum11. An anterior mesorectal dissection remains tumours at greater risk. Colorectal Dis 2001; 2(Suppl): 27.
posterior to Denonvilliers' fascia with the cavernous 7 Lindsey I, George BD, Kettlewell MGW, Mortensen NJMcC.
Impotence after mesorectal and close rectal dissection for bundles relatively protected by it. Use of the extrameso- in¯ammatory bowel disease. Dis Colon Rectum 2001; 44: 831±5.
rectal plane, exposing and staying immediately on the 8 Quah HM, Jayne DG, Eu KW, Seow-Choen F. Bladder and prostate and seminal vesicles, results in a resection of sexual dysfunction following laparoscopically assisted and Denonvilliers' fascia which can be identi®ed on the anterior conventional open mesorectal resection for cancer. Br J Surg surface of the extraperitoneal rectum11. As dissection is conducted in the plane anterior to Denonvilliers' fascia, the 9 Jones OM, Smeulders N, Wiseman O, Miller R. Lateral risk of damage to the cavernous nerves is theoretically ligaments of the rectum: an anatomical study. Br J Surg 1999; highest. While some surgeons recommend the routine use of this plane, in the authors' opinion it should be used only 10 Lepor H, Gregerman M, Crosby R, Mosto® FK, Walsh PC.
when the risk of leaving a tumour-positive anterior Precise localization of the autonomic nerves from the pelvic resection margin is high (when the tumour threatens the plexus to the corpora cavernosa: a detailed anatomical study of the adult male pelvis. J Urol 1985; 133: 207±12.
Sexual dysfunction in women after rectal surgery has not 11 Lindsey I, George BD, Warren BF, Mortensen NJMcC.
received much attention, and the surgical anatomy of the Denonvilliers' fascia lies anterior to the anterior plane of rectaldissection in total mesorectal excision. Colorectal Dis 2000; autonomic nerves and corresponding autonomic nerve lesions are poorly understood. This area presents consider- 12 Lindsey I, Kettlewell MGW, George BD, Mortensen NJMcC.
able opportunities for further research. In men the plane of Randomised, double-blind, placebo-controlled trial of anterior rectal dissection is now known to be critical with sildena®l (Viagra) for erectile dysfunction after proctectomy respect to sexual function; it should be de®ned relative to for rectal cancer and in¯ammatory bowel disease. Dis Colon Denonvilliers' fascia and the anterior mesorectum.
British Journal of Surgery 2002, 89, 1493±1494

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