Tympanometry and CT Measurement of Middle Ear Volumes in Patients with Unilateral Chronic Otitis Media.
OBJECTIVE
The goals of the study were to compare the middle ear (ME) volumes from both normal and lesioned ears, and these ME volumes were measured by a digital image processing computed tomography (CT) program in patients with unilateral chronic otitis media, and we wanted to compare the ME volumes of the lesioned ears by comparing the ME volumes obtained by tympanometry with those ME volumes measured by the digital image processing CT program.


METHODS
Forty-four patients who had unilateral chronic otitis media (COM) and contralateral normal tympanic membranes (TM) and 100 subjects with normal TMs were included in the study. The normal volumes of the external auditory canal (EAC) were measured in the normal group. The tympanometric ME volumes in the ears with a perforated TM were calculated as the difference of the tympanometric volumes measured from the both ears in patients with unilateral COM. The CT ME volumes were measured by a digital image processing program.


RESULTS
The tympanometric volumes of the EACs in the ears with normal TMs were 1.4+/-0.3 mL. There were no significant differences according to gender, age and the side of the face the ear was on. The tympanometric volumes of the EAC in the normal-side ear of the patients with unilateral COM showed no significant differences when compared with those from the normal group. The ME volumes of the intact ears, as measured by CT, showed significantly higher values than those ME volumes of the lesioned ears. The ME volumes of the lesioned ears, as measured by tympanometry, showed a strong, significant linear correlation with those ME volumes calculated by CT; however, the ME volumes of the lesioned ears, as measured by tympanometry (1.5+/-1.4 mL), were significantly larger than those ME volumes measured by CT (1.1+/-0.8 mL).


CONCLUSIONS
Our results show that chronic otitis media causes reduced ME volumes compared to those ME volumes of the contralateral normal ears. Tympanometry can provide a valuable estimation of the ME volumes in chronic ears, although it tends to overestimate the ME volumes, and especially for the ears with a larger ME volume.
Ahn
Jae-Yoon
JY
Department of Otorhinolaryngology-Head and Neck Surgery, Konkuk University School of Medicine, Seoul, Korea.
Park
Hong Ju
HJ
Park
Ga-Hyun
GH
Jeong
Yong-Soo
YS
Kwak
Hi-Boong
HB
Lee
Yeo-Jin
YJ
Shin
Jung-Eun
JE
Moon
Won-Jin
WJ