Abstract
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.
