Vol.102 No.1 contentsPRACTICA OTO-RHINO-LARYNGOLOGICA
Vol. 102 No. 1 January 2009
The Effect of Tympanic Membrane Perforation on
Middle Ear Sound Transmission
Yoichi Matsuda, Tomoyuki Kurita, Yoshihisa Ueda,
Shinsuke Ito and Tadashi Nakashima
(Kurume University School of Medicine)
Takakazu Matsuda
(Matsuda ENT Clinic)
It is well known that the magnitude of the conductive defect is primarily related to the size of the tympanic membrane perforation. However it is difficult to measure the perforation size. Furthermore if the perforation appears spindle-shaped or irregular, it is even more difficult to measure the size. In this study, we measured the size of traumatic perforation of the tympanic membrane in 24 cases using an image analysis system. The form of the perforation was classified to round form, spindle form and irregular form. The location of the perforation was classified based on the four quadrants of the tympanic membrane. Whether the perforation interfered with malleus function was also indecated. Then we analyzed the effect of the perforation of the tympanic membrane on sound transmission. The results were as follow.
1) The size of the tympanic membrane correlated closely with conductive hearing loss, and this correlation was closer for low frequencies than for high frequencies.
2) Conductive hearing loss was significantly smaller for round perforations at all frequencies.
3) The conductive hearing loss at high frequences was significantly larger for spindle-shaped perforations, anteroinferior perforation, and malleolar perforations.
Key words :tympanic membrane perforation, sound transmission, image analysis system