Fig 1.
Degrees of mastoid pneumatization with reference to the sigmoid sinus.
At the axial section where the malleoincudal complex (white arrow) appeared as an ice cream cone shape and the internal acoustic canal (black arrows) was identified clearly, three parallel lines angled at 45° to the anteroposterior axis (dotted line) were drawn. (A) Poor pneumatization: pneumatization remains anteromedial to the anterior line (passing the most anterior point). (B) Moderate pneumatization: pneumatization is between the anterior and middle (passing the most lateral point) lines. (C) Good pneumatization: pneumatization is between the middle and posterior (passing the most posterior point) lines. (D) Very good pneumatization: pneumatization is extended posterolaterally beyond the posterior line.
Fig 2.
Degrees of petrous apex pneumatization with reference to the carotid canal.
(A) None: no pneumatization present in the petrous apex. (B) Mild pneumatization: focal pneumatization is found either medial or lateral to the carotid canal. (C) Complete pneumatization: pneumatization is surrounding the carotid canal.
Fig 3.
Proportion of temporal bone fractures with otic-capsule violation.
Temporal bones with the reduced pneumatization were more likely to have OCV fractures than those with good pneumatization. TBF, temporal bone fracture; OCV, otic-capsule violating; OCS, otic-capsule sparing; asterisk, statistically significant (P< 0.05).
Fig 4.
Proportion of temporal bone fractures with sensorineural hearing loss (SNHL).
The less pneumatized temporal bone tended to have the greater the possibility of SNHL and the more severe degree of SNHL. The severity of SNHL was stratified using the average bone conduction thresholds at 0.5, 1, 2, and 4 kHz. TBF, temporal bone fracture; asterisk, statistically significant (P< 0.05).
Table 1.
Complication rate by the mastoid and petrous apex pneumatization degree.