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Originally published as JCO Early Release 10.1200/JCO.2008.20.8710 on January 21 2009 © 2009 American Society of Clinical Oncology.
Why Does Levator Ani Nerve Damage Occur During Rectal Surgery?Department of Colon and Rectal Surgery, Shizuoka Cancer Center, Shizuoka, Japan
Department of Surgical Oncology, Tokyo Medical and Dental University, Tokyo, Japan To the Editor: We read with great interest the article about levator ani nerve (LAN) damage during rectal cancer surgery by Wallner et al.1 The authors concluded that perioperative damages to the LAN might cause increased risk of both urinary and fecal incontinence after total mesorectal excision (TME), on the basis of Dutch TME trial data2 and anatomic consideration. Although we agree that the LAN plays a significant role in urinary and fecal incontinence, a more important point is the surgical procedure to dissect an appropriate surgical plane in TME that is more medial to the parietal pelvic fascia covering the LAN. The anatomic study by Wallner et al clearly showed that the LAN is covered by the parietal pelvic fascia, as did our study.3 The parietal pelvic fascia covers the sacral nerves and piriformis muscles, and continues to a fascia covering the ventral surface of the levator ani muscle (Fig 1). The parietal pelvic fascia is thick and divided into several laminae extending ventrolaterally. The most medial one covers the pelvic splanchnic nerves and pelvic plexus. In addition, the prehypogastric nerve fascia and the fascia propria of the rectum are located medially to the most medial sheet of the parietal pelvic fascia. The LAN runs through a deeper layer than do the urogenital nerves (ie, pelvic splanchnic and hypogastric nerves). The appropriate dissection plane in TME is between the fascia propria of the rectum and the prehypogastric nerve fascia, located medially to the parietal pelvic fascia.3–5
In the Dutch TME trial, 33.7% of patients experienced complications of urinary incontinence. On the other hand, urinary incontinence was reported by 0% to 10% of patients after TME in Japan.6–8 High incidence of sexual dysfunction was also reported in the Dutch trial. Erectile dysfunction was reported to have occurred among 21% of patients in the Dutch trial9 and 4% to 11% of patients in Japan,6–8,10 and ejaculatory dysfunction was reported to have occurred among 60% of patients in the Dutch trial and 25% to 27% of patients in Japan. This difference in dysfunction rates may be the result of differences in how the dissection plane in TME is determined in the Netherlands and Japan. The parietal pelvic fascia—which is thick and covers the LAN and muscles—can be easily recognized under direct vision with good countertraction, especially between the posterior wall of the rectum and the sacrum, and the fascia and LAN can be easily preserved. On the basis of their anatomic study, Wallner et al stated that a high-risk point of LAN injury occurs during dissection at the most distal part of the rectum. There are some variations in the interface between the levator ani and the anorectum.11 We agree that it is difficult to separate the levator ani and anorectum where the covering fascia of the levator ani changes into smooth muscles merging into the anorectal muscle. However, this level is the most distal part of the levator ani. Therefore, we are dubious that an injury at this level would play a role in functional disorder. In dysfunctions reported in the Dutch trial,9 nerves also seemed to be injured at the upper (ie, proximal) level. AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST The author(s) indicated no potential conflicts of interest. REFERENCES
1. Wallner C, Lange MM, Bonsing BA, et al: Causes of fecal and urinary incontinence after total mesorectal excision for rectal cancer based on cadaveric surgery: A study from the Cooperative Clinical Investigators of the Dutch total mesorectal excision trial. J Clin Oncol 26:4466–4472, 2008. 2. Marijnen CA, van de Velde CJ, Putter H, et al: Impact of short-term preoperative radiotherapy on health-related quality of life and sexual functioning in primary rectal cancer: Report of a multicenter randomized trial. J Clin Oncol 23:1847–1858, 2005. 3. Kinugasa Y, Murakami G, Suzuki D, et al: Histological identification of fascial structures posterolateral to the rectum. Br J Surg 94:620–626, 2007.[CrossRef][Medline] 4. Bissett IP, Hill GL: Extrafascial excision of the rectum for cancer: A technique for the avoidance of the complications of rectal mobilization. Semin Surg Oncol 18:207–215, 2000.[CrossRef][Medline] 5. Kinugasa Y, Murakami G, Uchimoto K, et al: Operating behind Denonvilliers' fascia for reliable preservation of urogenital autonomic nerves in total mesorectal excision: A histologic study using cadaveric specimens including a surgical experiment using fresh cadaveric models. Dis Colon Rectum 49:1024–1032, 2006.[CrossRef][Medline] 6. Maeda K, Maruta M, Utsumi T, et al: Bladder and male sexual functions after autonomic nerve-sparing TME with or without lateral node dissection for rectal cancer. Tech Coloproctol 7:29–33, 2003.[CrossRef][Medline] 7. Maas CP, Moriya Y, Steup WH, et al: A prospective study on radical and nerve-preserving surgery for rectal cancer in the Netherlands. Eur J Surg Oncol 26:751–757, 2000.[CrossRef][Medline] 8. Shirouzu K, Ogata Y, Araki Y: Oncologic and functional results of total mesorectal excision and autonomic nerve-preserving operation for advanced lower rectal cancer. Dis Colon Rectum 47:1442–1447, 2004.[Medline] 9. Rees PM, Fowler CJ, Maas CP: Sexual function in men and women with neurological disorders. Lancet 369:512–525, 2007.[CrossRef][Medline] 10. Sugihara K, Moriya Y, Akasu, et al: Pelvic autonomic nerve preservation for patients with rectal carcinoma. Cancer 78:1871–1880, 1996.[CrossRef][Medline] 11. Arakawa T, Murakami G, Nakajima F, et al: Morphologies of the interfaces between the levator ani muscle and pelvic viscera, with special reference to muscle insertion into the anorectum in elderly Japanese. Anat Sci Int 79:72–81, 2004.[CrossRef][Medline]
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Copyright © 2009 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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