Bony Dehiscence of the Horizontal Petrous Internal Carotid Artery Canal: An Anatomic Study with Surgical Implications

OBJECTIVE: The cervical carotid segment is used routinely as donor site for high-flow bypass procedures. The horizontal petrous segment would offer a shorter graft distance, complete graft protection intracranially, and avoid the need for surgical neck exposure. In a morpho-metric cadaveric study, we aimed to investigate variations of the petrous carotid anatomy, especially the incidence of bony dehiscence of the roof of the horizontal petrous carotid segment canal, which may facilitate exposure of the vessel and thereby potentially lower the morbidity of high-flow bypass procedures. METHODS: A subtemporal approach was used to expose the horizontal petrous internal carotid artery (ICA) on each side of 4 alcohol-embedded, silicone-injected human cadaver heads to perform a morphometric analysis of the vessel segment and surrounding bony anatomy. RESULTS: The following measurements were obtained of the horizontal petrous ICA (millimeters): long axis mean 9.6 (standard deviation [SD] 4.4, MIN 4.2, MAX 19.5), diameter mean 4.9 (SD 0.6, MIN 4, MAX 5.7), thickness of canal roof mean 2.1 (SD 1.7, MIN 0, MAX 5), and distance from temporal squama mean 22.5 (SD 6, MIN 17, MAX 35). Dehiscence of the bony roof of the horizontal petrous carotid canal was found in 25% of specimen investigated. CONCLUSIONS: A dehiscent bony roof of the horizontal petrous carotid canal potentially facilitates exposure of the vessel for high-flow bypass procedures and was observed in 25% of specimens. This feature could be identified on preoperative high-resolution imaging and thus aid in patient selection.