Microsurgical anatomy of the perigeniculate ganglion area as seen from the middle cranial fossa approach.

The middle cranial fossa approach is useful for decompressing the perigeniculate ganglion area of the facial nerve in patients with serviceable hearing. The present study was designed to investigate the microsurgical anatomy of the perigeniculate ganglion area of the facial nerve from the point of view of the middle cranial fossa. 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. These were found to be 22.7 degrees +/- 2.2 degrees and 6.5 +/- 0.3 mm, respectively. Detailed knowledge about the microsurgical anatomy of the perigeniculate ganglion area of the facial nerve from the point of view of the middle cranial fossa is imperative for facial nerve decompression by a middle cranial fossa approach.