Usefulness of the Attic Reconstruction Using the Tragal Cartilage and Perichondrium for Prevention of a Retraction Pocket.

Park,  Moon Il; Kim,  Chang Woo; Park,  Sun Min; Lee,  Jong Joo; Kim,  Hyeon Seong

Original Article

Auditory and vestibular disorders

Korean Journal of Audiology 2011;15(3):124-128.

Usefulness of the Attic Reconstruction Using the Tragal Cartilage and Perichondrium for Prevention of a Retraction Pocket.

Moon Il Park, Chang Woo Kim, Sun Min Park, Jong Joo Lee, Hyeon Seong Kim

Department of Otorhinolaryngology-Head and Neck Surgery, Hallym University College of Medicine, Seoul, Korea. kcw5088@dreamwiz.com

Abstract

BACKGROUND AND OBJECTIVES
Bone defect of the attic wall is a critical cause of the postoperative retraction pocket after canal wall up mastoidectomy. So, proper treatment of the attic defect is important and attic reconstruction is an acceptable procedure but it is controversial when the attic is reconstructed or not. The aim of this study is to analyze the usefulness of the attic reconstruction using tragal cartilage and perichondrium for prevention of retraction pocket and propose the indication to perform the attic reconstruction. SUBJECTS AND METHODS: We retrospectively reviewed the medical records of 46 consecutive patients who underwent tympanomastoidectomy and attic reconstruction using tragal cartilage between January 2005 and January 2009. The follow-up period varied from 12 to 65 months, with the average period of 34 months. We analyzed postoperative status of the scutum and the tympanic membrane, and development of the residual or recurrent cholesteatomas and evaluate development of the retraction pocket according to the preoperative size of the bony defect of the scutum and status of the ossicular chain.
RESULTS
Retraction pocket was developed in the 13% of the operations and most of the cases had large attic destruction more than 3 mm and destructed ossicular chain.
CONCLUSIONS
Attic reconstruction using tragal cartilage is a simple method to repair the bony defect of the external ear canal and effective in preventing postoperative retraction pocket if the size of destructed scutum is less than 3 mm.

Keywords: Reconstructive surgical procedure;Cholesteatoma;Ear canal;Cartilage

Address for correspondence : Chang Woo Kim, MD, Department of Otorhinolaryngology-Head and Neck Surgery, Hallym University College of Medicine, 150 Seongan-ro, Gangdong-gu, Seoul 134-701, Korea
Tel : +82-2-2224-2279, Fax : +82-2-482-2279, E-mail : kcw5088@dreamwiz.com

Introduction

Canal wall up mastoidectomy surgery is performed to preserve the external auditory canal posterior wall in patients who have a destroyed epitympanum due to middle ear disease or other surgical procedures. One adverse side effect of this surgery is the possibility of formation of a retraction pocket in the tympanic membrane. The degree of Eustachian tube disability that may occur due to attic retraction after middle ear surgery is also an important consideration. A number of factors including defects in the external auditory canal, such as attic destruction, are major causes of retraction pockets.¹⁾ The occurrence of a retraction pocket in the attic can induce ossicle erosion, thereby causing conductive hearing loss and progression to repetitive otorrhea or cholesteatoma as the retraction pocket worsens.
Therefore, an appropriate treatment is necessary to prevent bone loss in the epitympanum and the formation of a postoperative retraction pocket. The tympanic attic is typically reconstructed using bone fragments²⁾ or cavum conchae cartilage,^3,⁴⁾ or defects are treated with tragal cartilage⁵⁾ or artificial implants.⁶⁾ However, if maintenance of the normal structure of the attic fails after reconstruction, then canal down mastoidectomy surgery should be performed, which involves removal of the posterior external auditory canal posterior wall. Therefore, the choice of the appropriate method is important in handling bone defects of the epitympanum during the initial surgery.
In this study, the epitympanum was reconstructed using tragal cartilage and perichondrium in patients with attic destruction due to cholesteatoma. The effectiveness at preventing the formation of a retraction pocket was evaluated by observing and analyzing these patients postoperatively for more than a year. The findings reported here will help in the choice of an appropriate treatment method for attic destruction during the initial surgery.

Subjects and Methods

Subjects
Attic reconstruction was performed using tragal cartilage from January 2005 to January 2009. Patients' medical records and surgical findings were reviewed retrospectively for 46 patients who were available for follow-up for more than one year. The patients were 27 men and 19 women aged 12 to 72 years old (average age 43.1 years).
Attic reconstruction was only performed when bone destruction by the attic cholesteatoma was confined to the epitympanum. Exclusion criteria included cases of adhesion or retraction pocket in the pars tensa of the tympanic membrane, cholesteatoma in the middle ear, perforation or reoperation, Eustachian tube dysfunction, or unidentified pnuematization in the middle ear [such as sclerotic pneumatization in the mastoid from temporal bone computed tomography (CT)].

Operation (Fig. 1)
A posterior auricular skin incision was made and a musculoperiosteal flap (an anterior based flap) was formed. An external auditory canal skin incision was made in the direction of 5 o'clock to 10 o'clock for the right ear (2 o'clock to 7 o'clock direction for the left ear) at a distance of about 3 mm from tympanic ring. This incision was designed to pass the lateral portion of the bone destruction in the epitympanum area. A tympanomeatal flap was made to separate the tympanic membrane from the manubrium and to expose the destroyed bone area of the epitympanum. Mastoidectomy surgery and posterior tympanotomy was performed, and both cholesteatoma and granulation tissues were removed by removing the incus and malleus head, depending on the state of the cholesteatoma erosion. Cartilage was harvested from the ipsilateral tragus together with perichondrium. The harvested tissue was trimmed so that the perichondrium extended 2 mm beyond the cartilage border on one side, when designing cartilage to fit the size of the destroyed epitympanum. This tissue was placed between the bony portion of the external auditory canal and the temporalis fascia, for tympanic membrane insertion. The tympanomeatal flap was replaced to its original position and packed with Gelfoam. Surgery was complete after musculoperiosteal flap and posterior auricle skin suture.

Analysis
The size of the area of bone destruction was defined as the square root of multiplying two measurements: the anteroposterior diameter of bone destruction and the depth from neck of malleus (determined in 1 mm measurements by a micro-scale rater through the external auditory canal). Canal wall up mastoidectomy surgery and tympanoplasty were performed for removal of the cholesteatoma. Ossiculoplasty was performed depending on the state of the ossicle.
Outpatient follow-up after surgery was performed at 1, 3, 6, 9, and 12 months, and then every six months afterwards. Analysis of post-operative state was examined through a surgical microscope, and by ear endoscopy and temporal bone CT for the occurrence of a retraction pocket and the recurrence of cholesteatoma. The differences in air-bone gap were also investigated through audiometry performed pre and post-operation.
Attic retraction pocket was defined as discontinuity of the bony portion of the external auditory canal with a reconstructed epitympanum and medial displacement. Temporal bone CT was examined at one year and four year after surgery and pure tone audiometry test results were analyzed by calculating the arithmetic mean of pure tone hearing thresholds at 500 Hz, and 1, 2, and 3 kHz. A paired t-test and Chi-square test were used for statistical analysis, with a p value less than 0.05 considered significant.

Results

The postoperative follow-up period was 12 to 65 months, with an average of 34 months. The tympanic membrane for all cases recovered without any perforation and no recurrences of cholesteatoma were encountered (Fig. 2).
Postoperative temporal bone CT was performed on 34 patients and soft tissue density was observed on the epitympanum and mastoid cavity in 16 patients. In these 16 patients, a retraction pocket occurred in the epitympanum in six cases and canal wall down mastoidectomy was performed due to retraction progression (Table 1). The remaining 10 cases had no findings of eardrum abnormality based on ear endoscopy. No abnormalities were observed except for cicatricial tissue in 3 cases with experimental mastoidectomy. Attic destruction greater than 5 mm before surgery was seen in 4 cases. Only one case gave rise to a retraction pocket from these cases. Three cases gave rise to a retraction pocket from 15 cases with more than 4 mm and less than 5 mm destruction and 2 cases arose from 12 cases with more than 3 mm and less than 4 mm destruction.
No occurrences of retraction pockets were found in 15 cases with size of bone destruction less than 3 mm (Table 2). No statistically significant differences were found (p=0.068) for the occurrence of retraction pockets with respect to the size of the area of bone destruction. No occurrence of retraction pockets were found in 8 cases with a preserved malleus. Retraction pockets occurred in 5 cases out of 29 cases with removed malleus and in 1 case out of 9 cases with a removed malleus head (p=0.228).
Ossiculoplasty was performed in 21 out of 38 cases due to incus removal and 2 of these cases developed a retraction pocket. A retraction pocket developed in 4 of the 17 cases that did not undergo ossiculoplasty. The first appearances of retraction pockets were at 6 months in 2 patients and in one patient at 8 months and 9 months. The remaining 2 cases did not visit for check-ups after three months, but abnormalities were observed when they visited at 18 month and 22 months due to the development of otorrhea. A statistically significant difference (p=0.029)(Fig. 3) was found for the average air-bone gap in the pure tone audiometry test results for 13.7 dB postoperation compared to 17.2 dB preoperation in the 21 cases with ossiculoplasty.

Discussion

The occurrence of a retraction pocket when a canal wall up mastoidectomy surgery is performed is usually related to the degree of disability of the Eustachian tube. A number of factors will also have effects, including attic destruction and defects in the bony portion of external auditory canal. An appropriate treatment is therefore necessary to control bone loss of the epitympanum in order to prevent a postoperative retraction pocket. A number of materials are used for attic reconstruction, and canal down mastoidectomy is performed after removing the external auditory canal posterior wall when there is a large defect.
Materials used for reconstruction can be divided into artificial and autogenous material and autogenous material can be divided into bone and cartilage. Donald, et al.⁷⁾ reported a 17% of perforation and cholesteatoma recurrence after reconstruction of temporal fascia and use of silastic sheet on the defective parts during atticotomy. Zöllner and Büsing⁶⁾ used a tricalcium phosphate ceramic to reconstruct the epitympanum and the posterior wall of the external auditory canal and found that 15 out of 27 cases required reoperation to remove the implant. As seen in these cases, implantation of artificial materials can result in various problems during the engraftment process such as maintaining ear canal structure, especially in the presence of local inflammation. Sheehy, et al.⁸⁾ cut tragal cartilage into thin pieces to reconstruct the destroyed attic and ear canal to prevent retraction pocket development, and reported a recurrence of cholesteatoma of 5%. Pappas, et al.⁹⁾ used nasal septal cartilage to reconstruct the destroyed attic and reported recurrence of cholesteatoma of 13%. Adkins¹⁰⁾ used conchal cartilage to reconstruct the epitympanum.
Results of reconstruction using cartilage were relatively satisfactory. However, a retraction pocket and perforation can occur with an implant that is not fixed but mobile. Sakai, et al.²⁾ used a fragment from the mastoid bone to reconstruct the destroyed attic and found a recurrence of cholesteatoma and retraction pocket of 9%. Hinohira, et al.¹¹⁾ used cortical bone to reconstruct the destroyed attic and found an occurrence of retraction pocket of 6%. Bacciu, et al.¹²⁾ reported that cortical bone used for reconstruction became normal osseous tissue, as determined by histological study carried out one year after surgery. Cortical bone has been reported to be effective for developing an epitympanum structure and it is safe and easy to deal with. However, maintaining the form of the reconstructed area and the process for extracting the bone fragments are both difficult. The use of cortical bone also has disadvantages of bony absorption and exposure to infection.¹³⁾
Implant material can be easily collected when using targal cartilage for reconstruction. The use of targal cartilage also has an advantage in that sizing the cartilage to fit the exact size of bony defect can be done easily. In addition, cartilage is not absorbent compared to a bone fragment and it is able to survive with a deficient blood supply. It can also be easily removed with reoperation.¹⁴⁾ In the present study, tragal cartilage was trimmed so that the perichondrium extended 2 mm beyond the cartilage border on one side when designing cartilage to fit the size of bone destruction in epitympanum. The cartilage was also placed between the skin and bony portion of the external auditory canal to ensure stability of the reconstruction. Overall, six cases (13%) developed a tympanic membrane retraction pocket due to displacement of the implant, thereby necessitating reoperation.
Although no statistical significance was determined, the size of the area of bone destruction before surgery and the status of ossicle after surgery appeared to be important factors. No retraction pocket developed when the malleus was completely preserved and the size of the area of bone destruction was less than 3 mm. When the bone destruction area was greater than 3 mm, the implant cartilage was not sufficient for fixation. In this case, the malleus appears to play a large role in supporting the implant. When the entire malleus or malleus head is removed, the implanted cartilage can be supported with ossiculoplasty. However, in this case, displacement of the implant may occur when the bone defect is greater than 3 mm. Therefore, this procedure seems to be effective in attic reconstruction when the bony defect is less than 3 mm, or greater than 3 mm with a preserved malleus.
Follow-up of 4 cases showed retraction pocket development between six to nine months. Follow-up was discontinued in 2 cases that showed no abnormalities at 3 month after surgery. However, reoperation was carried out for development of retraction pocket at 18 and 22 months. A sufficient period of time is therefore required for postoperative follow-up. Early changes occurring within one year of attic reconstruction should be monitored for retraction pocket development. More close observations are considered necessary during this time.

Conclusion

Attic reconstruction can be easily reinforced using tragal cartilage and perichondrium. This procedure is considered to be effective in preventing postoperative retraction pocket for bony defects less than 3 mm, or when the malleus is preserved to support the tragal cartilage, and the Eustachian tube is well-functioning with no irreversible changes in the middle ear mucosa.

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