The Caroticoclinoid Ligament in Endoscopic Endonasal Transcavernous Surgery: Anatomical Variations, Operative Techniques, and Case Series

Objective: The caroticoclinoid ligament (CCL) suspends the medial wall of the cavernous sinus (MWCS) to the internal carotid artery (ICA) and anterior clinoid process. In endoscopic endonasal transcavernous surgery, safe transection of the CCL requires not only the knowledge of its familiar anatomy, but also the understanding of the possible variations. The aim of this study was to analyze the anatomical variations of the CCL, as well as the patterns of CCL invasion by pituitary adenomas (PA).

Methods: This study comprised an anatomical and a clinical analysis. Endonasal dissections of 20 specimens (40 sides) were performed to investigate the CCL variations. A retrospective analysis of 145 patients with PA invading the CS (160 CS sides; from 2018 to 2023) was conducted to report the incidence and patterns of CCL invasion.

Results: Anatomical analysis: The CCL was present in all investigated sides (n = 40). In the coronal plane, 1 CCL branch was found in 20 (50%), and ≥ 2 CCL branches in 20 sides (50%) ([Fig. 1]). The main CCL branch was defined as the medial continuation of the proximal dural ring, marking the transition from the cavernous to the paraclinoidal ICA. When additional accessory CCL branches were present, they attached to the paraclinoidal ICA (n=17, 53%), the horizontal segment (n = 10, 31.5%), and/or the anterior genu of the cavernous ICA (n = 5, 15.5%) ([Fig. 2A]). The CCLs attached most commonly to the upper (n = 29, 72.5%) and middle third (n = 26, 65%) of the MWCS ([Fig. 2B]). In the axial plane, the CCL was found to be a fenestrated membrane in 29 (72.5%; [Fig. 3A]), and an intact membrane in 11 sides (27.5%; [Fig. 3B]). All CCLs attached at least to the anterior third of the MWCS. Additionally, some CCLs attached also to the middle third (n = 23, 57.5%) and/or to the posterior third (n = 17, 42.5%; [Fig. 2C]). The CCL was connected to the inferior parasellar ligament in 14 sides (35%; [Fig. 4]).

Case series: Among all PA with CS invasion, the CCL was invaded in 36 cases (22.5%). Two patterns of CCL invasion were identified: (1) tumor adherent to the CCL fibers (n = 30, 83.5%) and (2) CCL thickened due to tumor growth within/along the fibers (n = 6, 16.5%).

Conclusion: This study represents a comprehensive analysis of the anatomical variations and patterns of invasion of the CCL, which is particularly relevant for the safe and effective resection of PA invading the CS.

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Artikel online veröffentlicht:
07. Februar 2025