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Middle ear morphology and mastoid pneumatization: a computed tomography study

Bernardo Alfonso Fernández-Reyes1, Santos Guzman-Lopez1, Francisco Javier Arrambide-Garza1, Pamela Garza-Baez2, Alejandro Quiroga-Garza1, Mario Campos-Coy2, Jose Luis Treviño-González3, Rodrigo Enrique Elizondo Omana1


Background: Mastoid pneumatization is subject to numerous influencing factors including race, sex, and surrounding structures of the middle ear. This study aims to determine the mastoid air cell system (MACS) volume and its relationship with middle ear structures, and the influence of sex.

Materials and methods: A cross-sectional study was performed analyzing computed tomography (CT) scans in which MACS volume and the Estachian tube length (ETL) were visible. MACS volume, ETL, and width and height of the aditus ad antrum were obtained.

Results: A total of 100 CT were included with a mean age of 38.5 ± 15.3 years, of which 56 were women and 44 were men. The mean right and left MACS volume were 5.43 ± 3.15 cm3 and 5.54 ± 3.43 cm3 respectively , with a ETL of 24.55 ± 3.07 mm in right side and 24.24 ± 2.60 mm on left side. A aditus ad antrum width of 2.98 ± 0.65 in right and 2.98 ± 0.58 on the left and height of  4.51 ± 1.05 and 4.32 ± 0.85, on right and left side  respectively. There were statistical differences between sexes in left ETL, and in MACS volume bilaterally. A low positive correlation between aditus ad antrum height and MACS volume was identified.

Conclusions: Mastoid pneumatization was bigger in men than women. There was a low positive correlation between mastoid volume and ETL on both sides, and a significant correlation between right mastoid volume and aditus ad antrum height. This could lead us to believe that the length of ETL does not affect the pneumatization of MACS.

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