Abstract
Purpose
Circumferential elevation of the anullus away from its bony seat and extension of the graft onto the anterior bony canal increase the bed of the graft anteriorly but may be associated with anterior blunting, and so, a significant conductive hearing loss may result. The purpose of this study was to compare the surgical and audiologic success rates of circumferential subannular grafting with the conventional underlay tympanoplasty.
Materials and Methods
A randomized clinical study was conducted from September 2007 to December 2010 at a tertiary referral center. Thirty-eight patients underwent circumferential subannular grafting (group A), and 25 patients underwent conventional underlay tympanoplasty with extension of the anterior edge of the graft forward against the lateral wall of the Eustachian tube, and therefore, the anterior sharp tympanomeatal angle remained unbroken (group B). All patients underwent preoperative and postoperative audiogram. Blunting and lateralization of the graft were evaluated 6 months after the surgery.
Results
The surgical success rate was 97% in group A and 100% in group B patients. Improvement of the air conduction thresholds in all frequencies and closure of the mean air-bone gap were significant and similar among the 2 groups. There were no cases of significant blunting and tympanic membrane lateralization in the 2 groups.
Conclusion
This study showed underlay tympanoplasty with elevation of the annulus away from the sulcus tympanicus in the anterior sharp tympanomeatal angle and placement of the graft between it and anterior bony canal is not associated with increased risk of blunting and lateralization of the graft, if that sharp angle is adequately restored.
1
Introduction
Tympanoplasty is defined as a surgical procedure to eradicate infection and restore the function of the middle ear. Underlay and overlay techniques refer to the placement of the graft either medial or lateral to the fibrous layer of the tympanic membrane (TM) remnant, first described by House and Shea , respectively.
The underlay technique, as the most common and easiest technique, is typically used for posterior perforations, whereas the overlay technique is more technically challenging and particularly suited for large or anterior perforations .
If the perforation is in the anterior half of the TM or if the perforation has a subtotal or total nature, then underlay tympanoplasty may fail because the anterior edge of the graft falls away from and fails to adhere to the anterior remnant of the TM. Although the lateral graft technique has a higher success rate for the reconstruction of anterior or subtotal TM perforations, serious complications including severe lateralization, blunting, and cholesteatoma formation may occur .
If the graft is positioned between the fibrous annulus and its bony annular seat and extended onto the anterior bony canal wall, then the risk of falling away of the graft from the anterior remnant of the TM and failure of grafting are minimized, but elevation of the annulus away from the sulcus tympanicus in the anterior sharp tympanomeatal angle and circumferential subannular grafting may be associated with blunting and remaining of the conductive hearing loss.
In the present study, we have compared the graft-take success rate, hearing results, and postoperative blunting and TM lateralization of circumferential subannular grafting with conventional underlay tympanoplasty.
2
Materials and methods
The present study is a randomized clinical study of patients with chronic otitis media (COM). Two groups of patients with COM were selected with random allocation. The sample size was determined to be at least 25 in each group. Thirty-eight patients in group A underwent a circumferential subannular grafting, and 25 patients in group B underwent conventional underlay tympanoplasty with extension of the anterior edge of the graft forward against the lateral wall of the Eustachian tube, and therefore, anterior sharp tympanomeatal angle remained unbroken. The study was conducted at a tertiary care referral center (Al’zahra hospital of Isfahan, Iran) from September 2007 to December 2010 on patients with COM and TM perforation in any size and location. Cases were excluded if the ossicular chain pathology, cholesteatoma or any acquired and congenital conditions associated with conductive hearing loss other than the TM perforation were documented, and if the maximum follow-up period was less than 6 months.
All patients underwent preoperative and postoperative audiograms. The perforation size (percentage of the TM) and location were obtained from sketches and intraoperative descriptions.
The senior author (FM) performed all surgeries in group B and junior author (SO) in group A patients.
Postoperative follow-up was performed 1 week, 1 month, 3 months, and 6 months after the surgery. First postoperative audiogram was obtained 3 months after the surgery. Postoperative complications including persistent perforation, TM lateralization, anterior blunting, and persistent hearing loss were assessed 6 months after the surgery (based on microscopic examination and second postoperative audiogram).
Data were statistically analyzed using SPSS software, version 14.0 (SPSS Inc., Chicago, IL). Patients and tympanic perforation characteristics between the 2 groups were evaluated with χ 2 test, preoperative bone and air conduction thresholds among the 2 groups with independent t test, and postoperative bone and air conduction thresholds difference of the 2 groups with analysis of covariance test. Significance was set at P < .05.
2
Materials and methods
The present study is a randomized clinical study of patients with chronic otitis media (COM). Two groups of patients with COM were selected with random allocation. The sample size was determined to be at least 25 in each group. Thirty-eight patients in group A underwent a circumferential subannular grafting, and 25 patients in group B underwent conventional underlay tympanoplasty with extension of the anterior edge of the graft forward against the lateral wall of the Eustachian tube, and therefore, anterior sharp tympanomeatal angle remained unbroken. The study was conducted at a tertiary care referral center (Al’zahra hospital of Isfahan, Iran) from September 2007 to December 2010 on patients with COM and TM perforation in any size and location. Cases were excluded if the ossicular chain pathology, cholesteatoma or any acquired and congenital conditions associated with conductive hearing loss other than the TM perforation were documented, and if the maximum follow-up period was less than 6 months.
All patients underwent preoperative and postoperative audiograms. The perforation size (percentage of the TM) and location were obtained from sketches and intraoperative descriptions.
The senior author (FM) performed all surgeries in group B and junior author (SO) in group A patients.
Postoperative follow-up was performed 1 week, 1 month, 3 months, and 6 months after the surgery. First postoperative audiogram was obtained 3 months after the surgery. Postoperative complications including persistent perforation, TM lateralization, anterior blunting, and persistent hearing loss were assessed 6 months after the surgery (based on microscopic examination and second postoperative audiogram).
Data were statistically analyzed using SPSS software, version 14.0 (SPSS Inc., Chicago, IL). Patients and tympanic perforation characteristics between the 2 groups were evaluated with χ 2 test, preoperative bone and air conduction thresholds among the 2 groups with independent t test, and postoperative bone and air conduction thresholds difference of the 2 groups with analysis of covariance test. Significance was set at P < .05.
3
Surgical technique
All procedures were performed under a general anesthesia with postauricular incision. After transaction of the canal skin and freshening of perforation margins, the tympanomeatal flap and annulus are elevated to expose the middle ear cavity and TM is released from the handle of malleus.
Placement of the graft was different between 2 groups:
- 1.
In group A, elevation of the flap and annulus continued until they became completely free from its seat. The middle ear was packed with Gelfoam (GELITA MEDICAL BV, Amsterdam) to support the graft. The graft is introduced medial to the TM remnant, and its anterior edge is positioned under the canal skin flap against the surface of the anterior bony canal wall. The remainder of the graft extended under the annulus, was draped over the short and long process of the malleus, and laid on the posterior bony canal wall. The fibrous annulus with tympanomeatal flap was then replaced into its original position but with the fascia between it and its bony annular seat. The annulus was packed against the bony sulcus tympanicus in the anterior with Gelfoam for recreating a sharp anterior tympanomeatal angle so as to prevent blunting as well as to prevent lateralization of the graft ( Fig. 1 ).
Fig. 1
Schematic illustration of circumferential subannular grafting technique.
- 2.
In group B, tympanomeatal flap and annulus were dissected until the 1-o’clock position superiorly and the 5-o’clock position inferiorly in the right ear. The graft was placed lateral to the malleus and medial to the drum remnant with extension of anterosuperior edge forward against the lateral wall of the Eustachian orifice. Then the graft was reflected anteriorly against the tympanomeatal flap for verifying of proper position of the graft, pushing it anterosuperiorly as much as possible, and filling of Eustachian tube orifice with Gelfoam. After the placement of adequate Gelfoam in the middle ear, the graft and tympanomeatal flap with annulus were replaced, and the graft was anchored between Gelfoam medially and TM remnant laterally. External auditory canal was filled with Gelfoam ( Fig. 2 ).
