Carotid Plexus Sympathetic Nerves as a Landmark for the Abducens Nerve within the Cavernous Sinus during Endoscopic Endonasal Surgery: Cadaveric Anatomical Study and Surgical Consideration

Background and Objectives: The abducens nerve is vulnerable to injury during the endoscopic endonasal transcavernous surgery. In this study, the authors aimed to develop the surgical anatomical landmark and the relationship between the sympathetic nerves around the internal carotid artery (ICA) and abducens nerve within the cavernous sinus (CS).

Methods: The relationship and patterns between the sympathetic nerves and abducens nerve were investigated in 15 cadaveric specimens (thirty sides). Intraoperative examples of this anatomical landmark are included.

Results: The sympathetic nerves around the ICA connecting to the abducens nerve can be classified into ascending sympathetic nerves and accessory sympathetic branches. The ascending sympathetic nerves divided into 3 types: 1) Type I has a single ascending sympathetic nerve with 2 subtypes: Type IA (17/30, 56.7%) was defined as a single ascending branch that ran into the abducens nerve, and Type IB (4/30, 13.3%) was defined as a single ascending branch with a terminal bifurcation before merging into the abducens nerve or lateral cavernous sinus wall; 2) Type II (7/30, 23.3%) was defined as 2 ascending branches that extend to the abducens nerve and the lateral cavernous sinus wall, and 3) Type III (2/30, 6.7%) was defined as 3 ascending branches that connect to the abducens nerve and lateral CS wall. The accessory branches of the sympathetic nerves were defined by sympathetic branches from the posterior genu or horizontal ICA and found in 6/30 sides (20%).

Conclusion: The authors propose a classification of the relationship of paraclival internal carotid artery sympathetic nerves and the abducens nerve within the CS as approached during endoscopic endonasal surgery. The consistent relationship of ascending sympathetic nerves and the abducens nerve within CS provides a reliable anatomic landmark during the endonasal approach to the CS.

Type of ascending sympathetic nerves within lateral cavernous sinus relating to abducens nerve
Type	n (%)(n = 30)
IA (single ascending branch)	17 (56.7%)
IB (single ascending branch with terminal bifurcation)	4 (13.3%)
II (double ascending branches)	7 (23.3%)
III (triple ascending branches)	2 (6.7%)

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Artikel online veröffentlicht:
07. Februar 2025