[Sectional anatomical analysis of auricular and middle ear malformation in patients with microtia].

Objective: To analyze the sectional anatomical features of auricular and middle ear malformation in patients with microtia so as to improve the clinical classification and the instruction of surgery.

Methods: From Jun. to Dec. 2009, 36 cases with microtia were selected in the center of auricular reconstruction in Plastic Surgery Hospital, including 22 cases of unilateral microtia and 14 cases of bilateral microtia. 22 patients with unilateral microtia were studied with the contralateral healthy ears as controls. Spiral CT was performed for high-resolution scan of the temporal bone. The coronal, sagittal and 3D reconstruction images were created with Mimic software. Several distances and degrees were measured.

Results: The patients were classified by Max classification. The anteroposterior diameter and the vertical diameter of tympanic cavity were (7.75 +/- 1.92) mm and (14.66 +/- 4.75) mm for type I; (6.17 +/- 2.56) mm and(14.35 +/- 5.12) mm for type II; (6.31 +/- 3.40) mm and (9.97 +/- 4.36) mm for type III (P = 0.001). The mastoid pneumatization degree for type I, II, III were 13.33%, 13.64%, 30.77% in sclerotic type, 13.33%, 18.18%, 7.69% in diploe type, 0, 9.09%, 38.46% in composite type, 73.33%, 59.09%, 23.08% in pneumatic type (chi2 = 24.11, P = 0.002). The cover of fenestra vestibuli by facial nerve was 21.43%, 47.62%, 54.55% (chi2 = 23.44, P = 0.002) for type I, II, III. There was a statistical difference between the microtia group and the control group.

Conclusions: According to the Max classification, the middle ear malformation changed along the auricular malformation. The anatomical variations was complicated in type II microtia, which should be sub-classified.