title: Using coronary computerized tomographic images to predict the bulging second genu of the facial nerve in mastoidectomy.
abstract: The aim of the present study is to determine whether coronary CT images of the temporal bone are useful to predict a bulging second genu of the facial nerve (SGFN) in mastoidectomy by measuring and comparing the heights of the SGFN above the prominence of the lateral semicircular canal (PLSC) in medial-to-lateral dimension on coronary CT images and in mastoidectomy. The relationship between the SGFN and the PLSC in medial-to-lateral dimension, which may have big variability, can be evaluated on the coronary CT images of the temporal bone. The heights of the SGFN above the PLSC in medial-to-lateral dimension were measured on coronary CT images and in mastoidectomy in 184 patients. If the SGFN is above the PLSC in medial-to-lateral dimension, we called the SGFN a bulging SGFN. The data measured on CT images and in surgery were described in histograms and compared. The sensitivity and the specificity in the diagnosis of a bulging SGFN on CT images were calculated by comparison with surgical measurement. Cohen's kappa coefficient was calculated. The heights of the SGFN above the PLSC measured in medial-to-lateral dimension varied from -2.9 to 2.9 mm on coronary CT images and varied from -3.0 to 3.0 mm in surgery. The data measured in surgery showed that the SGFN was above the PLSC in medial-to-lateral dimension in 27.7% (51/184) patients, at least 1 mm above the PLSC in 15.8% (29/184) patients and at least 2 mm above the PLSC in 6.0% (13/184) patients. The sensitivity and the specificity for CT diagnosis of a bulging SGFN were 100% (51/51) and 91.0% (121/133), respectively. Bulging SGFN can be predicted by measuring the height of the SGFN above the PLSC on coronary CT images of the temporal bone.
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, Eye and ENT Hospital, Fudan University, 83 Fenyang Road, Shanghai, 200031, China, doctorduqiang@163.com.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Du
authors.forename: Rujian
authors.initials: R
authors.lastname: Hong
authors.forename: Wuqing
authors.initials: W
authors.lastname: Wang
mesh_terms: D005154:Facial Nerve / Q000000981:diagnostic imaging*; D020220:Facial Nerve Injuries / Q000000981:diagnostic imaging / Q000517:prevention & control*; D005158:Facial Paralysis / Q000000981:diagnostic imaging / Q000517:prevention & control*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007431:Intraoperative Complications / Q000000981:diagnostic imaging / Q000517:prevention & control*; D008416:Mastoid / Q000000981:diagnostic imaging* / Q000601:surgery*; D011856:Radiographic Image Enhancement / Q000379:methods*; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D013701:Temporal Bone / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed / Q000379:methods*