Bony Dehiscence of the Horizontal Petrous ICA Canal—An Anatomic Study with Surgical Implications

Objective: The cervical carotid segment is routinely used as donor site for high flow bypass procedures, although the horizontal petrous segment in comparison, offers a shorter graft distance, provides complete graft protection inside the skull, and avoids the need for surgical neck exposure. In our morphometric cadaveric study, we aim to investigate variations in the petrous carotid anatomy, especially the incidence of bony dehiscence of the roof of the horizontal petrous carotid segment canal, which facilitates exposure of the vessel segment and thereby potentially lowers the morbidity of high flow bypass procedures.

Methods: A subtemporal approach was utilized to expose the horizontal petrous internal carotid artery (ICA) on each side of four 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 (mm): long axis mean 9.6 (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 specimen. This feature could be identified on preoperative high-resolution imaging and thus aid patient selection.