Vol.99 No.7 contentsPRACTICA OTO-RHINO-LARYNGOLOGICA
Vol. 99 No. 7 July 2006
Image of the Facial Canal Shown by
"3DX Multi-Image Micro CT"
Kazuomi Yamada
(Takanoko Hospital)
"3DX Multi-Image Micro CT" is a new three dimensional CT method using limited cone beam x-ray CT technology. A sensitive image intensifier transmits 512 X-ray pictures of a complex bony structure such as the temporal bone in a cylindrical area with a height of 30 mm and a diameter of 40 mm to a personal computer, where the X-ray data are processed into CT images. Axial (X), coronal (Y) and sagittal (Z) CTs along a desired slice plane are simultaneously displayed on the monitor. The author was able to measure the size of the bony facial canal with an image reconstruction. In 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. The result showed that 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, and then it gradually enlarged toward the stylomastoid foramen. There were no significant differences between data of the right and left sides. The same measurements were made in 16 patients with Bell's palsy and 8 with Hunt's syndrome. Abnormal enlargement of the facial canal distal and peripheral to the geniculate ganglion was observed only in the paralyzed side. The abnormality was closely associated with the grade of palsy and denervation. The results suggested that, in these diseases, the pathologic process involved the bony facial canal beside the facial nerve.
Key words :
three dimensional CT, cone beam x-ray, enlargement of the facial canal