Petrous Carotid Exposure with Eustachian Tube Preservation: A Morphometric Elucidation

Abstract

Inadvertent injury to eustachian tube leading to cerebrospinal fluid rhinorrhea is a known complication associated with drilling of Glasscock's triangle to expose the horizontal petrous internal carotid artery (ICA) for management of difficult tumors (especially malignant) or aneurysms at the cranial base. Contrary to the usual approach, we hypothesize that a ''medial-to-lateral'' approach to Glasscock's triangle drilling will minimize eustachian tube injury. Four formalin-fixed human cadaveric heads were dissected, and underwent appropriate morphometric analysis; yielding a total of eight datasets. The diameter of the horizontal petrous ICA exposed was 4.7 AE 0.9 mm (range, 3.8 to 5.6 mm).The mean distance from the medial carotid wall midpoint to the medialmost point on the eustachian tube was 6.35 AE 0.58 mm (range, 5.4 to 7.1 mm), yielding a ''safety zone'' for eustachian tube, ranging 0.2 to 1.9 mm lateral to the lateral carotid wall. With the medial-to-lateral approach, the eustachian tube remained preserved in all the specimens. The results of our study provide a practical, consistent, and safe method of maximizing horizontal petrous carotid artery exposure while minimizing the eustachian tube injury. KEYWORDS: Petrous, carotid, eustachian tube, morphometricThe last two decades have seen tremendous evolution in skull base surgery. Even though skull base surgical techniques have evolved over time, the postoperative morbidity and mortality associated with them are a major area of concern for the surgeon considering quality of life as an important outcome parameter gauging the operative success.Surgical management of complex aneurysms, vascular lesions, and tumors encasing or invading the internal carotid artery (ICA) located at the skull base necessitates the exposure of the horizontal segment of the ICA located in the petrous bone. The most popular approach described to achieve the latter is the middle fossa approach or its variants. [1][2][3][4][5] The complex anatomy * These authors have contributed equally in this study.

Low-flow and high-flow neurosurgical bypass and anastomosis training models using human and bovine placental vessels: a histological analysis and validation study

“…The diameters of the second-division segments approximated that of the M 1 (range 2.7-4.9 mm), 33 petrous ICA (range 3.8-5.6 mm), 3 and vertebral artery (range 2.5-4.0 mm). The diameters of the third-division segments were close to those of the ACA (range 1.0-3.0 mm), 34 M 2 -M 4 segments (range 0.8-3.5 mm), 34 STA (range 1.0-2.7 mm), 27 posterior inferior cerebellar artery (PICA) (range 0.6-1.8 mm), 34 and maxillary artery (mean ± standard deviation 2.8 ± 0.1 mm).…”

Maximizing the Petroclival Region Exposure Via a Suboccipital Retrosigmoid Approach

“…The complex anatomy of this area led to the definition of geometrical landmarks such as the Glasscock triangle and the middle fossa rhomboid for guiding the approach to these lesions while minimizing possible neurovascular complications. [3][4][5][7][8][9][10][11]20,24,26,27,[36][37][38][39] However, only scant information may be gathered from these studies on the topographic anatomy of the IICA through a suboccipital retrosigmoid approach; its deep position inside the petrous pyramid and the great variability in size and orientation of the petrous pyramid itself make its location challenging. In addition, IICA anatomy may be distorted by the pathology.…”

Fresh Cadaver Simulation Model with Continuous Extracorporeal Circulation as a Training Platform for Intracranial High-Flow Bypass: Technical Note and Rheologic Feasibility Evaluation

“…10 Risk of damage to the ET can be minimized by drilling from medial to lateral, that is, from the rhomboid area toward Glasscock's triangle. [11][12][13] We emphasize the importance of drilling the entire medial wall of the carotid canal to allow some mobilization of the petrous ICA and thus proper placement of both the temporary and permanent clips. We avoided drilling the lateral wall of the carotid canal: not only is the maneuver unnecessary, but it also poses high risk of injury to the ET and TTM.…”