Tympanic membrane perforation: size, site and hearing evaluation.

OBJECTIVE: To assess different clinical scales of TM perforation size; to evaluate the effect of the size and the site of a perforation on the hearing level and frequencies.

METHODS: Prospective study. Observers had subjectively estimated the size in millimeter and in percentage of a particular perforation; objectively computerized measures of TM perforations area were analyzed. Agreement between different measures was studied. Cases with postoperative intact TM and an air-bone gap (ABG) of 10 dB or less were studied.

RESULTS: Global mean preoperative ABG was 21.8 ± 17 dB. Preoperative ABG was different between small-large and small-total perforations (p=0.001). Difference of the preoperative ABG was statistically significant between perforations filling up the four quadrants and perforation limited to one quadrant in the postero-inferior, antero-superior and antero-inferior site. No statistically difference between perforation sites was identified for each affected frequency. Difference is statistically significant (p=0.001) between the 250 Hz and the other frequencies for the medium, large and total perforations. After myringoplasty bone conduction improvement was statistically significant for the frequencies 500 (p=0.04), 1000 (p=0.04) and 2000 Hz (p=0.011). Agreement was large enough when TM perforation size was expressed in percentage and absent when expressed in millimeter.

CONCLUSION: TM perforation can be clinically estimated quite precisely as a percentage of the TM area. Conductive hearing loss is frequency dependent; with the greatest loss occurring at the lowest sound frequencies. Hearing loss does not depend on the perforation's location.