Microsurgical Anatomy of Perigeniculate Ganglion Area of the Facial Nerve

Lee, Ho Ki; Kim, Hyun Jik; Lee, Won Sang

Abstract

BACKGROUND AND OBJECTIVES
Anatomical knowledge of microsurgical anatomy of the perigeniculate ganglion area is essential to the exploration of the facial nerve via translabyrinthine approach or middle fossa approach. This study was designed to investigate the surgical anatomy of the perigeniculate ganglion area of the facial nerve in view of translabyrinthine and middle fossa approach. MATERIALS AND METHOD: We dissected 15 human cadaveric temporal bones under a microscope and measured the lengths of the proximal part of tympanic segment, the labyrinthine segment, and the angle between the tympanic segment and the labyrinthine segment in the view of translabyrinthine approach. We dissected 20 human temporal bones under a microscope using a middle fossa approach, and measured the angle between the lines drawn from the malleus head to the vertical crest and from the malleus head to the geniculate ganglion, and the distance from the malleus head to the geniculate ganglion. RESULTS: The distance of facial nerve from the cochleariform process to the geniculate ganglion was 3.8+/-0.7 mm. The length of the labyrinthine segment of facial nerve was 4+/-0.8 mm. The angle between the tympanic segment and the labyrinthine segment in the view of translabyrinthine approach was 26+/-5degrees. The angles between the lines drawn from the malleus head to the vertical crest and from the malleus head to the geniculate ganglion, and the distance from the malleus head to the geniculate ganglion were found to be 23+/-2degreesand 6.5+/-0.3 mm, respectively. CONCLUSION: Precise knowledge about the microsurgical anatomy of the perigeniculate ganglion area of facial nerve is imperative for facial nerve decompression by a translabyrinthine and middle fossa approach.