DISCUSSION
All patients in this study underwent endoscopic myringoplasty without canaloplasty. Two cases were treated with sleeve resection of the EAC skin due to EAC stenosis. In addition to traditional endoscopic cartilage myringoplasty, an extra patch of perichondrium was used to enhance the anterior-inferior tympanic membrane if preoperative evaluation revealed dysfunction of eustachian tube or the graft did not tightly fit the residual tympanic membrane during operation. At sixth month follow-up, all the tympanic membranes healed well without fissure-like perforation or obtuse-angle healing, leading to a 100% healing rate of tympanic membrane. Although some patients had hypertrophy and swelling at the site of the extra patch, the symptoms improved during follow-up.
The audiological evaluation at month six post-operation showed significant decrease in ABG, compared with preoperative values. All patients had external auditory meatus healed smoothly and epithelized well, without bone exposure or granulation. Only a few minor complications were observed and all of these complications had resolved by the end of follow-up. These results and observation demonstrate that it is an effective and safe procedure to add an extra patch anterior to the graft and enhance the tympanic membrane.
Endoscopic myringoplasty has become popular in recent decades and its effectiveness and safety have been ascertained by multiple studies. Our previous study of endoscopic cartilage myringoplasty performed on CSOM patients achieved a healing rate of 97.4% in dry ear group and 96.9% in wet ear group (10). However, the small tympanic membrane residue of large perforation and anterior-inferior perforation provides less or no support to the graft and makes it difficult for the graft to tightly fit the tympanic membrane. A national multicenter study showed that the healing rate of large perforations was only 89.2%, much lower than those of small and medium perforations (100.0% and 93.7%, respectively). In terms of location, anterior perforations had the lowest healing rate of 92.4%, compared to 94.9% of inferior perforations and 95.6% of the posterior perforations (5).
In order to improve the healing rate of large,sub-total and anterior-inferior perforations, some scholars used the tympanic epithelial flap to repair marginal perforations and achieved a healing rate of 96.3% (6). However, this method only improves the healing rate of perforations no larger than 4 mm and critically depends on operators’ skills. Anterior wall flap separating were also applied to repair the marginal perforations and reported 100% heal of perforations, but it is only applicable for anterior (7).Different studies using butterfly cartilage reported healing rates of 96% (11) and 88% (8). This method improves the healing rate, but the high healing rate also heavily relies on surgeons’ skills. Due to the lack of precise measuring tools for tympanic perforation, the perforation size can only be roughly estimated by the operator, leading to inappropriate size of trimmed butterfly cartilage. Another drawback of butterfly cartilage method is the high risks in induced tympanitis, with reported incidence varying from 5% to 14% (12).
In order to improve the surgical outcome of patients with poor prognostic factors, we further enhanced the contact between graft and tympanic membrane remnant by adding an extra perichondrium patch anterior-inferior to a graft made of tragal cartilage perichondrium complex. We performed this procedure on patients with preoperative eustachian tube dysfunction, and patients with large or anterior-inferior marginal perforations whose grafts did not tightly fit the tympanic membrane during operation. This patch can be easily obtained by stripping perichondrium and cartilage on the parotid gland side of the well-prepared cartilage. Once the surgeon develops graft placement skills, this extra patching procedure can be completed within 1-3 minutes, without prolonging the operation or increasing patient financial burden. Patients in our study exhibited significant improvement in hearing after surgery, with both of the average PTA and the ABG significantly reduced six months after operation.
Although our method of adding an extra patch is easy to operate, surgeons’ skill is still critical. Improper operation may affect patch survival and a bulky patch may block the pharyngeal orifice of eustachian tube. There are some tips of adding an extra patch to reinforce the graft: (1) The perichondrium strip should be trimmed to 2-3 mm in width. (2) The prepared patch should be delivered to anterior-inferior area of the graft using forceps, and then a crochet hook should be used to fold the patch inward between the graft and the residual tympanic membrane to make the patch fit tightly with the graft surface, the anterior-inferior edge of the graft and the residual tympanic membrane. (3) If the fissure along the graft edge is large, a cartilage patch can be placed at the fissure firstly, before placing the perichondrium patch. Once the patching procedure is completed, gelatin sponge can be used to remove surface secretions. Operators can slightly press the gelatin sponge to smooth the patch and graft surface, and further check hidden fissures underneath.
This method benefits patients in the following situations. Firstly, patients who have eustachian tube dysfunction will benefit, because they are more prone to anterior-inferior fissures due to possible negative middle ear pressure. Secondly, this method will improve healing rates in patients who have no residual tympanic membrane to support the graft, or those whose tympanic membrane remnant does not closely fit the graft due to various reasons such as too small graft, graft of poor shape, or impossibility to retake a graft. In this case, an extra patch can be easily obtained by trimming the parotid perichondrium or the remaining cartilage. Thirdly, some patients have tympanic chamber left empty, and the grafts without anterior-inferior support could not closely fit the tympanic membrane. An extra patch offers additional support to the graft. Fourthly, for low-income patients who cannot afford biological materials or a secondary surgery, this method provides an affordable alternative.