In 2000, a new classification system of ossicular reconstruction was proposed by the Terminology Committee of Otological Society of Japan. We have often used this new classification to evaluate postoperative hearing after treatment by different surgical techiniques. In the present study, we assessed the postoperative outcome of Type III or IV tympanoplasty by measuring the hearing levels at various frequencies.
A total of 357 ears (189 right ears and 168 left ears) in 160 male and 197 female patients aged from 6 to 74 years who were followed up for at least six months were studied. The surgical technique was Type III-cin 125 ears, III-i in 117 ears, IV-c in 63 ears, and IV-i in 52 ears. The success rate of these techniques was 75%, 83%, 43%, and 58%, respectively. Overall, tympanoplasty was successful in 69%(248/357) of the patients. In these 248 successful cases, the improvement of hearing was examined at various frequencies. Comparison of the techniques with respect to the improvement of average hearing after surgery showed no significant differences between any pair of techniques. Then the improvement of hearing at each frequency was compared. The results showed that there were no statistical differences at 250, 500, or 1, 000 Hz, but the Type IV-i technique tended to achieve better hearing at 2, 000 Hz or higher frequencies and there was significantly better improvement than with the Type III-i technique. At 4, 000 Hz, the Type IV-i technique provided significantly better hearing than both the Type III-c and II-i techniques.