Doctor of Philosophy
Anatomy and Cell Biology
Allman, Brian L
Power, Nicholas E
Nerve-sparing is a well-established technique to preserve ejaculation in men undergoing retroperitoneal lymph node dissections (RPLND) for testis cancer. In the postchemotherapy setting, surgeons are faced with extensive disease, distorted anatomy, and increasingly complicated resections. As such, reports indicate that despite attempts to nerve-spare, 21-24% of patients still experience post-operative ejaculatory dysfunction. Worse yet, many institutions still do not attempt to nerve-spare, reporting ejaculatory dysfunction in 75-100% of patients. Although nerve-sparing may not always be indicated, experts conservatively estimate it is achievable in >50% of patients with advanced-stage disease in the post-chemotherapy setting. We contend that a poor understanding of the retroperitoneal sympathetic nerves has limited the efficacy, refinement and implementation of precise nerve-sparing practices during RPLND. Ultimately, success in nerve-sparing requires comfort with the normal neurovascular anatomy of the retroperitoneum; however, this is difficult to achieve because the relevant sympathetic networks (i.e., the aortic plexus) have not been comprehensively described and are often illustrated inconsistently. Therefore, the goal of the present thesis is to provide the first comprehensive characterization of the aortic plexus as it pertains to nerve-sparing RPLND. This was achieved through three specific aims: (i) to determine the organization of the aortic plexus by characterizing the anatomy of the constituent nerves and ganglia (Chapters 2 & 3), (ii) to describe the surgically-relevant variations of the lumbar splanchnic nerves adjoining the aortic plexus (Chapter 4), and (iii) to examine the neurovascular relationship between the sympathetic nerves of the aortic plexus and the lumbar vessels as it relates to RPLND (Chapter 5). Through dissection of human cadavers, the infrarenal aortic plexus was organized into two longitudinal cords, each containing two constituent ganglia. Two (range 1-4) lumbar splanchnic nerves (LSN), typically coursing anteromedial to the lumbar veins, join each cord. Despite varying in their position, 98% of LSNs originate from the lumbar sympathetic chains superior to the inferior mesenteric artery. In 85% of individuals, iv retroaortic LSNs coursed between the common iliac vessels to join the superior hypogastric plexus. Future studies should seek to determine the specific portions of the aortic plexus imperative to preserving ejaculation.
Beveridge, Tyler, "Anatomy of the Infrarenal Aortic Plexus: Implications for Nerve-Sparing Retroperitoneal Lymph Node Dissection" (2018). Electronic Thesis and Dissertation Repository. 5260.