The pterygoclival ligament: a novel landmark for localization of the internal carotid artery during the endoscopic endonasal approach

Abstract

OBJECTIVE The transpterygoid extension of the endoscopic endonasal approach provides exposure of the petrous apex, Meckel's cave, paraclival area, and the infratemporal fossa. Safe and efficient localization of the lacerum segment of the internal carotid artery (ICA) is a crucial part of such exposure. The aim of this study is to introduce a novel landmark for localization of the lacerum ICA. METHODS Ten cadaveric heads were prepared for transnasal endoscopic dissection. The floor of the sphenoid sinus was drilled to expose an extension of the pharyngobasilar fascia between the sphenoid floor and the pterygoid process (the pterygoclival ligament). Several features of the pterygoclival ligament were assessed. In addition, 31 dry skulls were studied to assess features of the bony groove harboring the pterygoclival ligament. RESULTS The pterygoclival ligament was identified bilaterally during drilling of the sphenoid floor in all specimens. The ligament started a few millimeters posterior to the posterior end of the vomer alae and invariably extended posterolaterally and superiorly to blend into the fibrous tissue around the lacerum ICA. The mean length of the ligament was 10.5 ± 1.7 mm. The mean distance between the anterior end of the ligament and midline was 5.2 ± 1.2 mm. The mean distance between the posterior end of the ligament and midline was 12.3 ± 1.4 mm. The bony pterygoclival groove was identified at the confluence of the vomer, pterygoid process of the sphenoid, and basilar part of the occipital bone, running from posterolateral to anteromedial. The mean length of the groove was 7.7 ± 1.8 mm. Its posterolateral end faced the anteromedial aspect of the foramen lacerum medial to the posterior end of the vidian canal. A clinical case illustration is also provided. CONCLUSIONS The pterygoclival ligament is a consistent landmark for localization of the lacerum ICA. It may be used as an adjunct or alternative to the vidian nerve to localize the ICA during endoscopic endonasal surgery.

Staging of T2 and T3 nasopharyngeal carcinoma: Proposed modifications for improving the current AJCC staging system

“…This may be because these two bony structures are relatively close to the nasopharynx and therefore more likely to be invaded in the early stages when the tumor is small and the prognosis better. Furthermore, these two bony structures are located within the pharyngobasilar fascia, which acts as a barrier to remote metastasis 19,20 . Once the tumor extends to the bony structures located outside the pharyngobasilar fascia, the risk of remote metastasis and death increases substantially.…”

Anatomical assessment of the endoscopic endonasal approach for the treatment of paraclinoid aneurysms

“…1A). 23,40 Next, a wide exposure of the skull base dura was performed. The sagittal extent of bone removal extended from the posterior end of the cribriform plate to the anterior sellar region.…”

Comparative Analysis of Surgical Exposure among Endoscopic Endonasal Approaches to Petrosectomy: An Experimental Study in Cadavers

“…The lateral pterygoclival ligament, fused with fibrocartilage at the foramen lacerum, is an important and constant landmark to identify the lacerum segment of the ICA. 15 The pterygoclival ligament, which originates at the junction between the pterygoid process and the posterior end of the vomer, consisted of the lateral end that merged with the anteromedial part of the foramen lacerum.…”

“…Neurovascular injuries, especially injury to the ICA, are the most important and relevant complications of petrosectomy and can be fatal. 23,24 In our study, we used the vidian nerve 14,25,26 and the pterygoclival ligament 15 to identify the lacerum ICA. The vidian canal was opened at the anterolateral edge of the foramen lacerum, whereas the pterygoclival ligament is fused with the anteromedial edge of the foramen lacerum.…”