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[Comparative evaluation of over-under myringoplasty and underlay myringoplasty for repairing tympanic membrane perforation].

OBJECTIVE
To evaluate the effect of over-under myringoplasty technique on repairing tympanic membrane perforation regarding with the rate of perforation closure, the frequency of postoperative complications occurrence and the level of hearing improvement.


METHOD
In this retrospective study, a total of 74 patients (77 ears) underwent myringoplasty and had been followed up for over 6 months, which was performed by means of the underlay technique in 44 patients (45 ears) and over-under technique in 30 patients (32 ears) from Jan 2002 to Jan 2007. In the underlay group, the grafted membrane was placed medial to the remaining drum and the manubrium of the malleus. In the over-under group, the grafted membrane was placed under the remaining drum and over the malleus. Comparatively evaluate the effect of the underlay technique and that of the over-underlay technique on repairing tympanic membrane perforation.


RESULT
The rate of perforation closure and hearing improvement in the underlay group of 45 ears was 89.0% and 57.5% respectively, while that in the over-under group of 32 ears were 87.5% and 71.9% respectively. The air-bone gap decreased by 4.9 dB in the underlay group, while it decreased by 9.7 dB in over-under group. After more than 6 months of following-up, the frequency of postoperative atelectasis of the underlay group and the over-under group was 17.8% and 6.25% respectively. Meanwhile, the frequency of postoperative reperforation of these two groups was 5.9% and 6.25% respectively. Blunting of the anterior angle of the tympanic membrane occurred in 3 ears in the over-under group. Lateralization of the graft was not observed in either group.


CONCLUSION
Over-under technique could reduce the occurrence of the adhesions between the grafted membrane and promontorium tympani by placing the grafted membrane between the remaining drum and the malleus. Furthermore, the level of hearing improvement in over-under group was higher than that in underlay group. Over-under myringoplasty is a more effective technique as comparison to underlay myringoplasty for repairing middle to large tympanic membrane perforations.