Clin Exp Otorhinolaryngol.  2008 Sep;1(3):139-142. 10.3342/ceo.2008.1.3.139.

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

• Ahn JY
• Park HJ
• Park GH
• Jeong YS
• Kwak HB
• Lee YJ
• Shin JE
• Moon WJ

• KMID: 1486083
• DOI: http://doi.org/10.3342/ceo.2008.1.3.139

Abstract

OBJECTIVES
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).
CONCLUSION
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.

Keyword

Mastoid; Tomography; Imaging; Three-dimensional; Acoustic impedance tests

MeSH Terms

Acoustic Impedance Tests
Aminocaproic Acids
Ear
Ear Canal
Ear, Middle
Humans
Mastoid
Otitis
Otitis Media
Tympanic Membrane
Aminocaproic Acids

Figure

• 

  Fig. 1 The distribution of external auditory canal (EAC) volumes according to age group. There was no statistically significant difference in EAC volumes between age groups. The mean values are illustrated with error bars indicating±1 SD.

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  Fig. 2 Middle-ear volimes by tympanometry and CT.

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  Fig. 3 The correlation of the middle-ear (ME) volumes measured by CT and tympanometry. The solid lines represent a best-fit linear regression line through the data points. Linear regression analysis gives a strong correlation coefficient (R-sq=0.85), and highly significant correlation (P<0.001). The dotted lines indicate a slope of 1 (CT volumes=tympanometric volumes).

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