Air pressure-sensing ability of the middle ear-Investigation of sensing regions and appropriate measurement conditions.
OBJECTIVE
To study the association between ear diseases and the ability of the middle ear to sense air pressure changes, we elucidated the appropriate conditions for measurements and confirmed the pressure-sensing regions while quantitatively assessing the pressure-sensing ability of normal ears and of ears with traumatic perforation of the tympanic membrane.


METHODS
In 318 normal ears (159 volunteers), an air pressure of 40daPas(-1) was loaded on to the external auditory canals to measure the minimum pressure sensed by subjects as a result of air pressure changes. The minimum pressure was defined as the minimum sensory threshold for air pressure loading (MSTAP; daPa). In 40 of 318 normal ears (20 volunteers), the MSTAP was measured at 10daPas(-1). Next, topical anesthesia was administered to 5 normal ears (5 volunteers), and the MSTAP was measured. In 7 ears with traumatic tympanic membrane perforation (7 cases), the MSTAP was also measured at the first medical examination. The data were analyzed using Stat View 5.0 (SAS Institute Inc., Cary, NC, USA). To test the significance of the data, the Mann-Whitney U-test and the Wilcoxon test were used.


RESULTS
The mean (+/-S.D.) MSTAP at 40daPas(-1) was -39.2+/-12.2daPa with negative pressure and 39.5+/-12.4daPa with positive pressure. At 10daPas(-1), the MSTAP was -70.3+/-25.0daPa with negative pressure and 72.5+/-22.7daPa with positive pressure, and both the mean and S.D. values were higher than those obtained at 40daPas(-1). Briefly, the MSTAP at 40daPas(-1) produced less variance than that at 10daPas(-1). The MSTAP demonstrated gender- and age-related variations. Moreover, it increased after topical anesthesia was administered to the tympanic membrane. The MSTAP in patients with traumatic tympanic membrane perforation was -205.0+/-26.3daPa with negative pressure and 206.0+/-26.7daPa with positive pressure, and was significantly higher than that observed in case of normal ears.


CONCLUSIONS
For obtaining accurate measurements while estimating the pressure-sensing ability of the middle ear, the rate of pressure loading should be considered. Although we assume that the middle ear has pressure-sensing regions other than the tympanic membrane, we conclude that the tympanic membrane is the most sensitive pressure-sensing region in the middle ear.
Sakata
Toshifumi
T
Department of Otorhinolaryngology, University of Fukuoka, School of Medicine, Nanakuma 7-45-1, Johnan-ku, Fukuoka 814-0180, Japan. sakata@fukuoka-u.ac.jp
Esaki
Yoshito
Y
Yamano
Takafumi
T
Sueta
Naoyuki
N
Nakagawa
Takashi
T
Kato
Toshihiko
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D000399:Air Pressure; D004056:Differential Threshold; D004432:Ear, Middle / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012677:Sensation; D014432:Tympanic Membrane / Q000293:injuries* / Q000503:physiopathology*; D014950:Wounds, Penetrating / Q000503:physiopathology*; D055815:Young Adult