Transoral Excision of a Huge Parapharyngeal Space Pleomorphic adenoma: A Possibility of Changing the Surgical Consideration to a Minimally Invasive Approach

Case Report

Transoral Excision of a Huge Parapharyngeal Space Pleomorphic adenoma: A Possibility of Changing the Surgical Consideration to a Minimally Invasive Approach

Corresponding authorDr. Mutlaq Al-Sihan, Consultant ORL-HNS, Reconstructive HNS & Facialplasty, Chairman of ORL-HNS Department Al-Jahra Hospital Kuwait, Tel: +965 50132311; Email: al_sihan@yahoo.com

Abstract
Two cases of external auditory canal cholesteatoma arising in the posterior wall were treated using an operative method we devised. After antrotomy with an open technique, depending on the size of the residual mucosa in the antrum, cortical bone plate was used to close the space between the posterior external canal and the antrum . Additionally, the posterior external auditory canal wall was reconstructed with the cortical bone plate and temporal fascia. The concepts of this operative method include safe operation with wide operative fields, preservation of the gas exchange function in the residual normal antrum in the middle ear and protection against postoperative retraction of the wound. In both of 2 cases treated using our operative method some volume of the mastoid cavity could be preserved and it showed no debris pooling, otorrhea or recurrence of external auditory canal cholesteatoma.

Keywords: External Auditory Canal; Cholesteatoma; Cavity Problem; Mastoidectomy Reconstruction of Posterior Wall of External Auditory Canal   

Introduction
External canal auditory cholesteatoma arising from the posterior canal wall is often treated by canal wall down mastoidectomy. The open method, which has a longer history than the closed method, is a surgical procedure that removes the canal wall and provides an opening of the mastoid cavity that extends toward the external auditory canal. This surgical procedure seems to be of value in preventing relapses of cholesteatoma otitis media. A clear operating field is maintained together with superior ease in cleaning the ear. However, patients undergoing the open-method surgery may develop cavity problems, such as otorrhea and the formation of granulation tissue [1]. Epithelization of surgically-induced wounds in the mastoid cavity extending toward the external auditory canal is retarded, and the accumulation of crust leads to repeated infection. Therefore, we treated two cases of external auditory canal cholesteatoma arising in the posterior wall using an operative method we devised. The concepts of this operative method include safe operation with wide operative fields [2], preservation of the gas exchange function in the residual normal antrum of the middle ear and protection against postoperative retraction of the wound. This paper describes how our new method contributed to a satisfactory postoperative course in 2 cases.

Methods

Two cases of external auditory canal cholesteatoma arising in the posterior wall were treated using our newly devised operative method. In this operative method, after antrotomy with an open technique, depending on the size of the residual mucosa in the antrum, the cortical bone plate is used to close the space between the posterior external auditory canal and antrum. Additionally, the posterior external auditory canal wall is reconstructed using the cortical bone plate and temporal fascia (figure 1).

Figure 1.New surgical procedure for reconstruction of the posterior .

Results

Case 1:

Preoperative CT shows an external canal cholesteatoma arising in the posterior wall of the external auditory canal, but the antrum was intact (Figure 2).

Figure 2. (Case 1). Left: external canal cholesteatoma (arrow) of the right ear.

Right: In the preoperative CT, an external canal cholesteatoma (arrow) was found in the posterior wall of the external auditory canal, but the antrum was intact.

Postoperative CT shows the cortical bone and fascia together with the reconstructed posterior wall; note the mostly preserved aeration in mastoid cells and the absence of retraction (Figure 3).
Fine-needle aspiration cytology showed pleomorphic adenoma. Surgical options were discussed with the patient, explaining the procedure, complications (including converting the transoral route to a transcervical approach,and the possibility of need for a tracheostomy and mandibulotomy), and the follow- up plan.
Figure 3 (Case 1): Postoperative CT showing the cortical bone (arrow) used to reconstruct the posterior wall, the mostly preserved aeration in mastoid cells and the absence of retraction.
Case 2:

Preoperative CT in case 1 shows an external canal cholesteatoma
(arrow) arising in the posterior wall that invaded a part of
the antrum (Figure 4).
Figure 4 (Case 2): On preoperative CT, an external canal cholesteatoma (arrow) that invaded a part of the antrum was found in the posterior wall.
Most mastoid cells and the antrum mucosa were clear after removing the external canal cholesteatoma, which had invaded the posterior external canal wall and antrum mucosa. A defect of the posterior wall was reconstructed using cortical bone and fascia (Figure 5). Postoperative CT shows the cortical bone used for reconstruction of the posterior wall, and the partially preserved aeration of the mastoid cells. In the postoperative findings, the fascia covering the cortical bone (arrow) had undergone epithelization and was dry without a retraction pocket (Figure 6).
Figure 5 (Case 2): In the operative findings, a right external canal cholesteatoma (arrow) could be observed retracting the posterior meatal skin flap (*) (Left).

Most mastoid cells and the antrum were clear after removing the external canal cholesteatoma that (Middle).
The defect of the posterior wall was reconstructed using cortical bone (arrow) (Right).

In both cases treated with our operative method we could preserve some volume of the mastoid cavity without debris pooling, otorrhea or recurrence of external auditory canal cholesteatoma.

In the follow-up visit three months postoperatively, the patient was doing well and there were no further complaints. The last radiological CT neck follow-up two years later was done and showed no recurrence (Figure 5).
Figure 6 (Case 2): Postoperative CT (Left) showing cortical bone (arrow) used to reconstruct the posterior wall, and the preserved aeration in a part of the mastoid cells.

In the postoperative findings (Right), the fascia covering the cortical bone (arrow) had undergone epithelization and was dry without a retraction pocket.

Discussion
When an external auditory canal cholesteatoma arising from the posterior canal wall is treated by canal wall down mastoidectomy, an advantage of our method is that we can check whether the cholesteatoma has invaded the antrum and confirm facial nerve runs by observing a horizontal semicircular canal. Therefore, in such cases, canal wall down mastoidectomy contribtes to safe removal of the choteasteatoma tissues in retrofacial mastoid cells. In fact, cholesteatomas of such cases nearly occupy the retrofacialmastoid cells from the posteriorcanal wall, but show an intact antrum.

Reported cavity problems include: (A) ventilatory dysfunction induced by the occurrence of retraction in the mastoid antrum, and the accumulation of debris and crust there, and (B) difficulty in obtaining a dry ear at surgically-induced wounds because of mucous production in the residual mucosa of the mastoid antrum and the mastoid air cells, which cannot be completely removed with a bar, leading to the retardation of healing. In order to eliminate the cavity problems listed in (A), a lower facial ridge is created and the opening of the external auditory meatus isenlarged at the time of operation [3]. However, these treatments seem not to be helpful in dealing with the problems listed in (B).

With our new surgical procedure, we reconstruct canal wall taking into account the size of the normal mucosa of the mastoid
antrum and the mastoid air cells and lesion. Construction of the external auditory canal is performed using the cortical plate of mastoid bone and temporal fascia, which excludes the lesion and preserves the mucosa of the intact middle with a closed mastoid cavity. Surgically-induced wounds will not be exposed to the mucous produced in the intact mastoid antrum and mastoid air cells. Therefore, our surgical procedure was helpful in minimizing the occurrence of retraction and in obtaining a dry ear without debris pooling, otorrhea or the recurrence external auditory canal cholesteatoma. The duration of healing seems to be shortened due to the limited surface area of surgically-induced wounds in the external auditory canal. In addition, the preserved mucosa of the intact mastoid antrum and mastoid air cells continues to exchange gases and the pneumatic system in the tympanic cavity is less frequently affected [4,5]. As mentioned above, in our surgical procedure the middle ear cavity is formed as a result of reconstruction of the canal wall, which is performed in proportion to the size of the preserved mucosa of the middle ear (the intact mastoid antrum and mastoid air cells). In canal reconstruction, a conventional surgical procedure, the size of the reconstructed canal wall is determined not by the size of the preserved mucosa of the middle ear but by the original size of the canal wall. This surgical procedure provides a larger middle ear cavity, but will put excessive pressure on the eustachian tube [1]. If the middle ear cavity becomes too large, the gases contained inside it cannot be completely exchanged by the preserved mucosa. Negative pressure will be created, and thus patients will have an increased incidence of retraction in the reconstructed parts, destruction loss due to the retraction and even difficulty with the sound-conducting mechanism.

The advantage of mastoid obliteration, the other conventional surgical procedure, seems to be the same as that of canal reconstruction. The occurrence of retraction is rare and the duration is shorter, because the surface of surgically-induced wounds in the external auditory canal is limited. However, as with other surgical procedures, problems develop after this surgery. Mucus production in the residual mucosa of the mastoid antrum and the mastoid air cells that produce mucus cannot be removed by a bar completely, thus leading to the postsurgical development of cysts in the obliterated parts of the mastoid cavity [6]. In contrast, in our surgical procedure, cysts may develop less frequently, because the middle ear cavity is formed in proportion to the size of the preserved mucosa of the middle ear and the gas-exchange function is maintained.

In another reported surgical procedure, differing from ours, the canal wall is reconstructed using only soft material or the temporal fascia [7]. Hard material that would otherwise prevent retraction is not placed inside surgically-induced wounds. Patients will thus be at higher risk of severe retraction. Ventilatory dysfunction will result from retraction of the mastoid antrum, which, as we mentioned, is one of the causes of cavity problems, and the amount of accumulated debris and crust will increase there. Because of the retraction, the middle ear cavity no longer exhibits gas exchange and the ultimate goal of the closed method is not achieved.

References

1. Sade’J, Berco E, Brown M. Results of mastoid operation in various chronic ear diseases. Am. J. Otol. 1981, 3(1): 11-20.

2. Honjo I. Middle ear diseases from the viewpoint of gas exchange function in the mastoid. Practica. Otologica (Kyoto). 1988, 91: 1-7.

3. Sanna M, Sunose H, Mancini F, Russo A, Taibah A. Middle ear and mastoid microsurgery. Thieme New York. 2003, 2ndEdition, 612.

4. Sade J, Luntz M. Gaseous pathways in atelectatic ears. Ann Otol Rhinol Laryngo. 1989, 98: 355-358.

5. Takahashi H, Honjo I, Naito Y, Miura M et al. Gas exchange function through the mastoid mucosa in ears after surgery. Laryngoscope. 1997, 107(8): 1117-1121.

6. Shinkawa A. Reconstruction of posterior meatal wall and obliteration after canal wall down operation. Johns. 1993, 9: 810-814.

7. Hosoi H, Murata K. Tympanoplasty with reconstruction of soft posterior meatal wall in ear with cholesteatoma. Auris Nasus Larynx. 1994, 21: 69-74.

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