Microsurgical anatomy of the perigeniculate ganglion area as seen from a translabyrinthine approach.

Detailed anatomic knowledge of the microsurgical anatomy of the perigeniculate ganglion area is essential to probing adjacent to the facial nerve by a translabyrinthine approach. This study was designed to investigate the surgical anatomy of the perigeniculate ganglion area of the facial nerve from a translabyrinthine point of view. We dissected 15 human temporal bones under a microscope, measured the lengths of the tympanic segment and the labyrinthine segment by a middle cranial fossa approach, and measured the angle between the tympanic and labyrinthine segments by a translabyrinthine approach. The distance of the facial nerve from the cochleariform process to the geniculate ganglion was 3.8+/-0.7 mm. The length of the labyrinthine segment of the facial nerve was 4 +/-0.8 mm. The angle between the tympanic and labyrinthine segments from a translabyrinthine point of view was 26 degrees +/-5 degrees. Precise knowledge about the microsurgical anatomy of the perigeniculate ganglion area of the facial nerve from a translabyrinthine viewpoint is imperative for facial nerve decompression by a translabyrinthine approach.