Key Techniques and Outcome Analysis of Endoscopic Mastoid Revision Surgery

Introduction

Radical mastoidectomy is a classic surgical procedure for treating middle ear and mastoid lesions. Its goal is to remove lesions in the middle ear and mastoid, connect the external auditory canal, mastoid, tympanic cavity, and antrum into a single large cavity, and achieve dryness of the operated ear. Dry ear is considered one of the objective evaluation criteria for radical mastoidectomy [1]. The most common symptom of radical mastoidectomy failure is persistent otorrhea. Some scholars have defined “discharging surgical cavities” as those requiring frequent outpatient cleaning of cerumen impaction and prone to discomfort after water exposure, frequent infections, or otorrhea [2]. In this study, “dry ear failure” refers to the persistence of otorrhea, recurrent infection, or the need for frequent cavity cleaning beyond the expected healing period, encompassing anatomical, infectious, and pathological causes. The most common cause is cholesteatoma recurrence (including residual or recurrent cholesteatoma [3]), followed by external auditory canal stenosis, excessively high facial ridge, insufficient removal of anterior and posterior bone walls, and incomplete mastoid cavity drilling [4,5]. Once a discharging surgical cavity develops postoperatively, patients require frequent outpatient follow-ups and even multiple surgeries, which not only affect the function of the affected ear but also restrict the patients’ activities and social interactions [2,6,7]. In such cases, revision radical mastoidectomy is necessary.

The core of mastoid revision surgery is to thoroughly remove residual or recurrent lesions and optimize the anatomical structure of the surgical cavity to resolve persistent infections, cholesteatoma recurrence, and other issues, ultimately achieving dryness of the operated ear, preventing disease progression, and improving hearing.

This study aimed to analyze the causes of discharging surgical cavities in patients undergoing mastoid revision surgery and to summarize the techniques and outcomes of endoscopic radical mastoid revision surgery.

Material and Methods

ETHICS STATEMENT:

This study was approved by the Ethics Committee of Shenzhen Nanshan People’s Hospital (approval No. LW-2025-18).

STUDY PARTICIPANTS:

We conducted a retrospective analysis of 47 patients who underwent endoscopic radical mastoid revision surgery at Shenzhen Nanshan People’s Hospital from 2020 to 2024. Pediatric patients with cholesteatoma were excluded. All included patients developed discharging surgical cavities 1 to 18 months after primary radical mastoidectomy.

SURGICAL PROCEDURE:

All patients underwent preoperative temporal bone computed tomography (CT; 0.6 mm slice thickness), pure-tone audiometry, eustachian tube function assessment, and endoscopic ear examination. Revision mastoidectomy was performed under general anesthesia using a continuous irrigating endoscopic mode. All surgeries were performed by the same experienced otologists and were video recorded. Data included causes of discharging cavities, materials used for mastoid obliteration, and operative duration.

POSTOPERATIVE MANAGEMENT:

Patients received antibiotics for 7 days, and the cavity was packed with antibiotic gauze for 3 weeks. After removal, the cavity was cleaned under endoscopy every 1 to 2 weeks, and endoscopic images were documented. Complications, time to dry ear, dry ear rate, and hearing improvement were recorded. Follow-up ranged from 6 to 18 months.

STATISTICAL ANALYSIS:

SPSS software (version 26.0) was used for statistical analysis. Paired-sample t tests were applied to compare pre- and postoperative air conduction and air-bone gap thresholds. A P value <0.05 was considered statistically significant.

Results

GENERAL RESULTS:

The average age of the 47 patients was 38.74 years (range, 23–66), with 53.19% male and 46.81% female patients. The primary disease was middle ear cholesteatoma in 78.72% (37/47) and chronic otitis media in 21.28% (10/47). Among patients with chronic otitis media, 5 were diagnosed with cholesteatoma during revision surgery, 31.91% (15/47) had initial surgery at our hospital, while 68.09% (32/47) were referred from other hospitals.

CAUSES OF DISCHARGING CAVITIES:

All patients underwent preoperative temporal bone CT scanning, endoscopic ear examination, and pure-tone audiometry, providing sufficient imaging information for the surgery. Among the 47 ears, the causes of discharging cavities were insufficient surgical cavity opening (44.68%, 21/47), cholesteatoma recurrence (51.06%, 24/47), poor surgical cavity drainage (59.57%, 28/47), and lesions at the tympanic orifice of the eustachian tube (45.74%, 21/47), with perilabyrinthine and retrofacial air cells being the most common site for insufficient opening and cholesteatoma recurrence, excessively high facial ridge as the primary factor for poor drainage, and inflammatory mucosal edema as the main lesion type at the Eustachian tube orifice. Multiple causes coexisted in some cases. The specific causes are shown in Table 1.

KEY SURGICAL TECHNIQUES:

All 47 ears underwent open radical mastoidectomy under general anesthesia using the continuous irrigation mode of the total ear endoscope. Total or partial ossicular chain reconstruction was performed based on the intraoperative ossicular preservation status, and external auditory canal plasty was performed for all 47 ears. Typically, tinfoil sheets or inverted door-shaped incisions were used to protect the skin flaps (Figure 1A). During surgery, the unidirectional impact force of continuous perfusion was used to sharply dissect adhesions in the surgical cavity under water using a microcurved needle or microscissors, which effectively protected the tympanic cavity mucosa and well exposed important structures, such as the facial nerve and stapes (Figure 1B). A disposable soft ruler was used intraoperatively to measure and select an artificial ossicle of precise length for hearing reconstruction (Figure 1C). For patients with membranous or osseous hyperplasia at the eustachian tube orifice, a spinal anesthesia tube was used for cannulation, with 5 cm of the tube left indwelling in the eustachian tube (Figure 1D). For mastoid cavity packing, concentrated growth factor (CGF) combined with hydroxyapatite was used to fill the mastoid cavity, and CGF was used to cover the external auditory canal skin incision to promote healing (Figure 1E, 1F).

OPERATIVE TIME AND OUTCOMES:

The operation time of the 47 patients was counted from the start of skin incision to the end of auditory canal packing, with an average of 125.17±45.05 minutes. Among the patients, 17.02% (8/47) had shallow surgical cavities, which were packed with tragus cartilage fragments; 82.98% (39/47) had large surgical cavities, which were packed with serum-soaked hydroxyapatite, with the surface covered by cartilage and CGF membrane. One patient did not undergo hearing reconstruction during surgery. Postoperatively, 3 patients experienced transient taste disturbance, and no complications, such as vertigo, facial paralysis, or severe sensorineural hearing loss, occurred. The postoperative dry ear rate (defined as intact tympanic membrane, no pus or proliferative granulation tissue in the surgical cavity, and no cholesteatoma recurrence) was 100%, with an average dry ear time of 75.16±31.44 days. All 47 patients were followed up for 6 to 18 months, and good epithelialization was observed (Figure 2). Statistical analysis showed that hearing was significantly improved at 6 months after surgery, compared with the preoperative period (P<0.05, Figure 3). No cholesteatoma recurrence was observed in the 47 patients during the follow-up period.

Discussion

DISEASE DISTRIBUTION:

In this retrospective cohort study, among the 47 included patients, 5 had primary chronic otitis media, which later progressed to middle ear cholesteatoma. The invasive biological behavior of middle ear cholesteatoma may be an intrinsic factor leading to the high incidence of discharging surgical cavities, as its lesions are prone to residual cholesteatoma in hidden air cells (such as perilabyrinthine and sinodural angle regions). For patients with chronic otitis media, secondary cholesteatoma formation should be vigilantly monitored postoperatively. It is worth noting that once dry ear failure occurs, patients’ compliance and satisfaction will decrease. Among the 47 patients in this study, 32 were patients who experienced dry ear failure after their first surgery in other hospitals, which also indicates the importance of improving the postoperative follow-up system for the early detection of surgical cavity problems. Qualitative comparison revealed that referral cases (68.09%) often presented with more advanced pathology (eg, extensive cholesteatoma recurrence), whereas internal failures (31.91%) were more frequently associated with technical factors such as high facial ridge or inadequate cavity drilling. This highlights the importance of early detection and anatomically adequate primary surgery.

MULTIFACTORIAL ANALYSIS OF DRY EAR FAILURE:

We defined dry ear failure as a discharging cavity requiring revision, characterized by persistent otorrhea, recurrent infection, debris accumulation, or cholesteatoma recurrence. The main causes of dry ear failure are insufficient cavity opening, cholesteatoma recurrence, poor drainage, and lesions at the tympanic orifice, consistent with global reports [1,2,4,5,8–16]. There are also some systemic factors such as diabetes and fungal infections caused by the humid climate in southern China. Therefore, it is particularly important to expand the external auditory canal and lower the facial ridge to ensure smooth drainage during surgery.

However, the proportion of various causes of dry ear failure varies greatly in previous literature reports. All surgeries in the 47 patients in this study were performed under total ear endoscopy. Cholesteatoma epithelium around the tensor tympani tendon and between the anterior and posterior crura of the stapes was observed in 2 cases, which has not been mentioned in previous literature reports. Similarly, the proportion of insufficient mastoid opening caused by factors such as anteriorly positioned sigmoid sinus, low-lying middle cranial fossa plate, and high jugular bulb in microscopic surgery, as reported in previous literature, was significantly lower in the present study. Endoscopic surgery allowed better exposure and reduced issues such as sigmoid sinus prolapse or low-lying dura [17–22].

SKIN FLAP PROTECTION TECHNIQUE AND COMPLETE SEPARATION OF SURGICAL CAVITY EPITHELIUM: For patients undergoing revision surgery, protecting the external auditory canal skin flap during surgery is of great significance to prevent postoperative auditory canal stenosis and achieve rapid dry ear. Based on the previous surgical experience of our center and reports from other studies [23–25], we adopted the “inverted door–shaped incision” method. Specifically, the skin flap is pulled out of the external auditory canal in the reverse direction and fixed with a retractor. Then, the skin layer of the discharging surgical cavity is carefully separated, and the granulation tissue or eroded skin in the skin layer is trimmed, while the normal epithelium is preserved as intact as possible. Under the irrigation condition, the skin flap is placed at the tympanic-meatal angle and protected with tinfoil sheets. After surgery, no complications, such as auditory canal stenosis or scarring, occurred.

CONTINUOUS IRRIGATION MODE: In addition, all cases in this study were operated under the continuous irrigation mode (CIM). In endoscopic ear surgery, the CIM can create a continuous, stable, and clear underwater surgical operation environment. It can expel substances such as a small amount of intraoperative bleeding and bone powder out of the surgical cavity, thereby avoiding endoscopic contamination and maintaining a clear surgical field of vision for a long time, which is conducive to improving the surgical efficiency and enhancing the surgical safety [26]. For patients undergoing revision surgery of radical mastoidectomy, especially when there are adhesive tissues in the tympanic cavity, it can be difficult to identify important structures such as the stapes, facial nerve, and horizontal semicircular canal. Moreover, the mucosal hyperplasia or adhesion in the tympanic cavity can also lead to difficulties in separation, resulting in mucosal exfoliation and postoperative re-invagination or adhesion. However, under the CIM, the amount of bleeding is significantly reduced, and the unidirectional impact force of water also has a certain separation effect. In this mode, we can perform blunt separation of the adhesions in the tympanic cavity and carefully identify important structures such as the stapes, facial nerve, and horizontal semicircular canal. After surgery, none of the 47 cases had complications such as sensorineural hearing loss, facial paralysis, or vertigo. Therefore, CIM can reduce intraoperative bleeding, improve visualization of critical structures (facial nerve, stapes), and facilitate adhesion dissection with no associated complications.

HEARING RECONSTRUCTION TECHNIQUE: For patients undergoing revision surgery, the postoperative mucosal swelling and adhesion of the promontory of the tympanum, scar thickening, and grinding and expansion of the external auditory canal and facial ridge during the first operation all require accurate judgment of the length of the ossicles needed for hearing reconstruction. Based on previous experience, we used a disposable soft ruler [27], which was cut into a strip with a length of about 5 mm and a width of about 1 mm for accurate measurement. After surgery, there was no case of excessively long ossicles. Except for 1 patient who did not undergo hearing reconstruction, the other 46 patients experienced significantly improved hearing.

EUSTACHIAN TUBE PROTECTION TECHNIQUE: In this study, 22 patients had eustachian tube lesions of varying degrees. In the era of microscopic surgery, it was relatively difficult to expose the eustachian tube orifice. During the endoscopic ear surgery, by using a 30° endoscope and tilting the operating table to the opposite side of the surgeon, the lesions at the eustachian tube orifice can be exposed and treated, and the condition of the tympanic orifice of the eustachian tube can be clearly displayed. Eustachian tube dysfunction is one of the common causes of middle ear cholesteatoma. With the mature application of balloon dilation in sinus ostium opening, some scholars have used eustachian tube balloon dilation for the treatment of eustachian tube dysfunction and achieved satisfactory results [28–30]. However, performing Eustachian tube balloon dilation at the same time will prolong the operation time and increase the economic burden of patients due to its high cost. Meanwhile, performing tympanic membrane tube insertion at the same time imposes the risks of postoperative infection and inability to remove the tube. Therefore, we used a 5-cm spinal anesthesia tube to cannulate from the tympanic orifice to the pharyngeal orifice of the eustachian tube and left the tube indwelling. The tube was removed from the nasopharynx about 3 months after surgery, to avoid the risk of eustachian tube stenosis. However, due to the small sample size, the long-term effect needs further follow-up observation.

MASTOID CAVITY OBLITERATION TECHNIQUE: In revision surgery, the completely opened mastoid air cells, the lowered facial ridge, and the posterior wall of the external auditory canal still form a large cavity. More bone defects and difficulties in obtaining autologous materials are the problems in mastoid cavity obliteration during revision surgery. Currently, many biological materials are used for mastoid cavity obliteration, such as bioactive glass, hydroxyapatite, bone cement, titanium mesh, silica gel, and artificial dermis [31]. The use of synthetic materials for mastoid cavity obliteration is also a relatively safe and effective treatment method [32–34]. Our center previously conducted a study on the effect of hydroxyapatite combined with autologous CGF in mastoid cavity obliteration during endoscopic middle ear cholesteatoma surgery [35]. Among 58 patients with cholesteatoma, only 2 patients (3.4%) had hydroxyapatite extrusion, which was much less than that reported in other literatures. In the 47 revision surgeries of this study, 8 patients with shallow surgical cavities were treated with tragus cartilage fragments for obliteration, and 39 patients with large surgical cavities were treated with serum-soaked hydroxyapatite, with the surface covered by cartilage and CGF membrane. CGF can promote angiogenesis and the proliferation and migration of epithelial cells through its rich cytokines, enhance the anti-infection ability, and shorten the epithelialization time of the surgical cavity [36,37]. After surgery, all patients had good epithelialization and no hydroxyapatite extrusion. Therefore, using hydroxyapatite combined with tragus cartilage for obliteration of the surgical cavity in revision surgery can not only solve the problem of difficulty in obtaining materials for patients undergoing the second operation but can also shorten the epithelialization time by using the healing-promoting effect of CGF, reduce the number of postoperative follow-up visits of patients, and improve patient satisfaction.

EFFICACY EVALUATION AND TECHNICAL LIMITATIONS:

Through the abovementioned surgical techniques and operations in this study, the average operation time was 125.17±45.05 minutes. There is no report on the time of revision surgery in previous studies. However, compared with the operation time of the first radical mastoidectomy performed in our center during the same period, there was no significant difference. Although the surgical difficulty increased, with the rational application of various operating techniques, the operation time was not significantly extended. Except for 1 case, in which stapes sclerosis and fixation were found during the operation and hearing reconstruction could not be performed simultaneously, hearing reconstruction was performed in 46 cases. The postoperative hearing of these patients was significantly improved compared with the preoperative level, and no obvious complications occurred. The postoperative dry ear rate was 100%, and the average dry ear time was 75.16±31.44 days, which was the same as the dry ear time after the first cholesteatoma surgery in the previous study of our center, and significantly shorter than the dry ear time after simple hydroxyapatite obliteration [37].

To date, no cholesteatoma recurrence has been found during follow-up. However, this study still has certain limitations. For example, due to the retrospective design, the details of the first operation for cases from other hospitals are missing, and the follow-up period (6–18 months) is insufficient to evaluate long-term recurrence beyond 5 years. We are prospectively following this cohort to report extended outcomes in future work. In addition, for cases with indwelling drainage tubes for eustachian tube lesions, the sample size is small, and a larger sample size is required for verification in the later stage.

Conclusions

Endoscopic revision surgery effectively resolves discharging mastoid cavities, achieving a 100% dry ear rate and significant hearing improvement. Techniques such as continuous irrigation and CGF-enhanced obliteration contribute to surgical safety and enhanced recovery.