The Relationship between Traumatic Tympanic Membrane Perforations and Pneumatization of the Mastoid

Abstract

We evaluated the possible relationship between tympanic membrane perforations resulting from blast trauma or slap and pneumatization of the mastoid cells. A total of 25 male patients with tympanic membrane perforations resulting from blast injury (n = 7), slap (n = 17), and football hit (n = 1) and 20 healthy male volunteers without any ear problem had temporal bone computed tomographic scans in the axial plane, parallel to the infraorbitomeatal line, with 2 mm slice thickness and 2-mm intervals using bone algorithm with a ProSpeed Spiral tomography machine. The area of air cells in each slice was measured using trace and area measurement functions of the tomography machine, and by multiplying the resulting area by slice thickness, the volume of each slice was calculated. For each ear, the total of volumes of air cells was calculated by adding the volumes of each slice containing air cells. The calculated volumes of mastoid cells were evaluated by comparing microscopic findings. Both patient and control groups consisted of males, and their ages ranged from 17 to 32 (mean 24.5) years. Microscopic examinations revealed that perforations were frequently located in the lower quadrants and that most of them were less than 3 mm. There were no pars flaccida and marginal perforations. Ossicular chain destruction was noted neither in temporal bone tomographic nor during intraoperative examinations. The mean (± SD) volumes of right and left ear mastoid air cells in patient and control groups were 6.92 ± 2.45 vs. 7.00 ± 2.59 cm³ and 9.04 ± 4.55 vs. 8.95 ± 4.53 cm³, respectively, and the differences were not statistically significant. It was found that the level of mastoid pneumatization has no statistically significant effect on tympanic membrane pathologies due to blast or other injuries.

Tympanometry and CT Measurement of Middle Ear Volumes in Patients with Unilateral Chronic Otitis Media

“…It has also been reported that the average ME volumes in the normal ears, as measured using CT, were 5.6-7.9 mL, which is similar to our results (3-6). …”

Positional relationship between the facial nerve and other structures of the temporal bone

“…The method of evaluating pneumatization in this study was precise and convenient, and differed from the previous studies. [11][12][13][14][15][16][17][18] The volume of pneumatization including air cells and tympanic cavity was calculated and found to be similar to other studies. [13][14][15][16][17][18] It was found x The authors speculate that this information may be of help to surgeons that there were correlations between the pneumatization and all the measured parameters of the facial nerve.…”

Middle ear pressure change as a function of body position

“…An estimation of the ME volume change required to generate the measured postural pressure change was calculated by employing Boyle's law of gases: P 1 × V 1 = P 2 × V 2, where P is the pressure and V is the volume. The volume of ME cleft ( V 1) was taken as 8 mL, which may be considered the average normal aerated mastoid size 8–10. The initial, upright pressure ( P 1) was atmospheric pressure (10,000 mmH 2 O) + the tympanometric average upright recording.…”