Anterior facial nerve rerouting in cranial base surgery: a comparison of three techniques.

Anterior rerouting of the facial nerve is a maneuver designed to enhance exposure of the jugular foramen and carotid canal during resection of cranial base tumors. Our clinical impression is that the degree of additional exposure afforded by moving the facial nerve varies considerably according to both anatomic variations and the technique used. Three possible techniques exist based on the extent of facial nerve mobilization and point of rotation: canal wall up-second genu pivot point (CWU-2G); canal wall down-second genu pivot point (CWD-2G); and canal wall down-first genu pivot point (CWD-IG). We anatomically studied 20 human cadaver heads to establish clinically relevant guidelines for the selective use of these techniques. At the level of the dome of the jugular bulb, the facial nerve mobilized anteriorly a mean of 4.2 mm for CWU-2G, 10 mm for CWD-2G, and 14 mm for CWD-1G. Detailed analysis of numerous measurements and rotation angles suggests that the typical exposure afforded by the various rerouting techniques is as follows: CWU-2G, complete exposure of the jugular bulb; CWD-2G, exposure of the jugular bulb and a mean of 6 mm of the posterior aspect of the carotid artery; and CWD-IG, exposure of the jugular bulb and entire carotid genu. Minimizing the amount of facial nerve manipulation needed to achieve sufficient surgical exposure helps optimize postoperative functional status.