Paraclival or Cavernous Internal Carotid Artery: One Segment but Two Names.

BACKGROUND The anatomy of the carotid artery has traditionally been understood into segments that correspond to the surrounding relevant anatomy. Transcranial surgery favors the seven segments classification initially posited by our group in 1996. With the advent of endoscopic approaches a new term has been added to the carotid anatomy lexicon "the paraclival internal carotid artery (ICA)." This "paraclival" carotid is a very familiar segment for all endoscopically trained skull base surgeons but a clear correlate to the transcranial anatomy has not been described. The purpose of our study is to improve the communication between endoscopic and open trained skull base surgeons by correlating the endoscopic paraclival ICA to the transcranial segments of the ICA. METHODS Two cadaveric specimens underwent both endoscopic and transcranial dissection. Aneurysm clips were placed in the proximal and the distal extent of the paraclival ICA as described in previous literature. The clip positions were visualized and correlated to open anatomical landmarks. RESULTS The proximal clip was located just medial to the origin of the petrolingual ligament, while the distal clip was placed just inferior to the posterior genu of the cavernous ICA. CONCLUSION The paraclival ICA corresponds to lacerum segment of ICA and vertical cavernous ICA.