[The effect of hyalinized chorda tympani nerve canal in protection of mastoid segment of facial nerve in middle ear surgery].

OBJECTIVE

To investigate the effect of hyalinized chorda tympani nerve canal in mastoid segment to landmark facial nerve in middle ear surgery by means of observing the location relationship between hyalinized chorda tympani nerve canal and facial nerve.

METHOD

118 cases of cholesteatoma otitis media in our hospital undergoing tympanoplasty from 2008 to 2011 were retrospectively analyzed. In all the cases, the position of horizontal semicircular and fossa incus as well as the hyalinized chorda tympani nerve canal were used for landmark the height of facial ridge and vertical segment of facial nerve.

RESULT

The chorda tympani nerve of 99 patients were higher than the vertical segment of the facial nerve which were not exposed, and the vertical segment of the facial nerve in 9 patients, which were exposed, were 1-2 mm lower and 2-3 mm ahead or backward than the chorda tympani nerve. The horizontal semicircular and fossa incus were broken in 9 patients, of whom the vertical segments of the facial nerve were 1-2 mm lower and 2-3 mm ahead or backward than the chorda tympani nerve. The chorda tympani nerve of 1 patient were lower than the exposed vertical segment of facial nerve.

CONCLUSION

The hyalinized chorda tympani nerve canal in mastoid segment can landmark the positon of facial ridge, and it would be the complement to the traditional method of landmarking vertical segment of facial nerve, especially for those whose horizontal semicircular canal and fossa incus had been broken.