Transoral Excision of a Huge Parapharyngeal Space Pleomorphic adenoma: A Possibility of Changing the Surgical Consideration to a Minimally Invasive Approach
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).
Preoperative CT shows an external canal cholesteatoma arising in the posterior wall of the external auditory canal, but the antrum was intact (Figure 2).
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.
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).
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 the postoperative findings (Right), the fascia covering the cortical bone (arrow) had undergone epithelization and was dry without a retraction pocket.
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 . 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 . 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 . 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 . 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.
2. Honjo I. Middle ear diseases from the viewpoint of gas exchange function in the mastoid. Practica. Otologica (Kyoto). 1988, 91: 1-7.
6. Shinkawa A. Reconstruction of posterior meatal wall and obliteration after canal wall down operation. Johns. 1993, 9: 810-814.