The value of preoperative CT scan of tympanic facial nerve canal in tympanomastoid surgery.

Conclusions: The combined analysis of axial, coronal, and sagittal planes can increase the positive rate of diagnosis for dehiscence of the facial nerve canal. Objective: The aim of this study was to evaluate the diagnostic value of high resolution computed tomography (HRCT) scanning of the condition of the tympanic portion of the facial nerve canal in patients with chronic otitis media. Methods: A total of 76 ears of 72 inpatients with chronic suppurative otitis media and with cholesteatoma or granulation tissues in the attic were examined by routine HRCT. The condition (including dehiscence) of the tympanic portion of the facial nerve canal observed by CT on multi-planar images and surgical findings were recorded. Results: The condition of the tympanic portion of the facial nerve canal observed by CT could be confirmed by surgical findings in 67/76 ears, but was not confirmed in 9/76 ears. Axial-transverse images could clearly show the position and length of dehiscence on the lateral wall of the facial nerve, while coronal images were superior to axial-transverse images in showing the bony circumference of the facial nerve, and sagittal images could show the inferior wall of the facial nerve canal more clearly than images on the former planes. [ABSTRACT FROM AUTHOR]