Abstract
OBJECTIVE
A cone beam 3D-CT with a flat panel, named Accuitomo, provides high-resolution images of minute bony structures such as facial canal. Here, we investigate diameter of bony facial canal to reveal pathological change due to facial palsy.
METHOD
First, in the 28 normal adult volunteers the diameters of the bony facial canals were measured at the meatal foramen, the cocleariform process, the stapes, the pyramidal eminence and emerging point of the chorda tympani in the vertical segment. Second, the same measurements were made in the 16 patients with Bell's palsy and 8 with Hunt's syndrome.
RESULTS
The facial canal had two narrow sites, one at the meatal foramen and the other at the level of the stapes. From the meatal foramen toward the geniculate ganglion the canal gradually enlarged. From here the canal again became narrower until the level of the stapes. Then it gradually enlarged toward the stylomastoid foramen. The diameters at each point of facial canal measured by a cone beam CT agreed with those previously measured in cadaver temporal bones. In the paralyzed side, significant enlargement of the facial canal distal and peripheral to the geniculate ganglion was found. The grade of enlargement correlated with grade of facial palsy and of denervation.
CONCLUSION
The results suggested that in theses diseases pathologic process involved the bony facial canal adjacent to the facial nerve.