Mastoidectomy is a classic procedure for the treatment of middle ear and mastoid lesions. Its purpose is to debride lesions of the middle ear and mastoid; connect the external auditory canal, mastoid, tympanic cavity, and antrum into single a large cavity; and achieve a dry ear. Unfortunately, hearing reconstruction is often ignored when performing mastoidectomy.  With the development of new technologies, canal wall down and canal wall up mastoidectomy along with tympanoplasty have become the main methods by which to treat middle ear or mastoid lesions.  For patients with a wide range of lesions in the middle ear or mastoid cavity and for patients with mastoid dysplasia, canal wall down mastoidectomy is an effective treatment option. Mastoid obliteration and plastic repair of the cavity of the concha, which expands the external auditory meatus orifice for adequate ventilation of the open mastoid cavity, can achieve a dry ear in the early period. Reconstruction of the posterior and superior canal wall and ossiculoplasty have become the mainstream surgical techniques with which to improve hearing. [3–7] However, many problems still remain, such as a narrow auditory meatus orifice after canal wall down mastoidectomy, a high facial ridge, a recurrent or residual cholesteatoma, and residual air cells, because of great differences among clinicians in the understanding of ear microscopy, temporal bone anatomy, pathophysiology, and disease prognosis.  Surgical failure is more frequent in patients with more severe disease; with residual tegmental, apical, and sinodural cells causing persistent or intermittent ear discharge; and with hearing loss after both canal wall up and canal wall down mastoidectomy as the initial procedures, which prompts them to seek irregular long-term treatment and results in great economic and psychological burdens. [9,10] Therefore, development of revision surgery techniques is urgently needed. This study was performed to analyze the preoperative and intraoperative findings and functional results of revision surgery after canal wall down mastoidectomy.
Patients and methods
This retrospective longitudinal cohort study was approved by the Ethics Committee of the First Affiliated Hospital, Wenzhou Medical University, China (approval No. 2008-05-02A11) on May 2, 2008. Patients who had undergone revision canal wall down mastoidectomy from March 2006 to March 2017 in the Department of Otology of the First Affiliated Hospital, Wenzhou Medical University were included in this study. The inclusion criteria were a duration of >1 year since surgery and regular hospital visits for examination and treatment of persistent or intermittent otopyorrhea of the diseased ear. The exclusion criteria were otorrhea or a duration of <1 year since canal wall down mastoidectomy, otorrhea after canal wall up mastoidectomy, diabetes, and severe cardiopulmonary dysfunction. Finally, 34 patients with complete data were enrolled in our study. The patients comprised 14 males and 20 females with monaural lesions ranging in age from 17 to 68 years (mean, 42.6 ± 24.8 years). Of these 34 postoperative patients, 28 were from an outside hospital and 6 were from our hospital. Twenty-six patients had a cholesteatoma, 2 had chronic otitis media (cholesterol granuloma), and 6 had an unknown pathological status at the time of presentation because a long period of time had passed since mastoidectomy. During the follow-up of 3 to 40 years after mastoidectomy, the patients often experienced persistent or intermittent otopyorrhea. Moreover, many patients had purulent secretions or dry scabs in the tympanum or mastoid cavity that needed to be cleaned regularly. Three patients experienced 1-week duration of dizziness, nausea, vomiting, and stumbling at 10, 18, and 40 years, respectively, after surgical treatment of cholesteatomas. All patients provided written informed consent.
Endoscopic inspection (Karl Storz endoscope; Karl Storz, Tutlingen, Germany) was performed for further confirmation before the operation. All 34 patients were found to have a narrow auditory meatus orifice and a large amount of pus and crusts in the tympanum or mastoid cavity. After cleaning, cholesteatoma epithelium was seen in the mastoid cavity or tympanum of 20 patients, a large retraction pocket was seen in the epitympanum and retrotympanum of 2 patients (Fig. 1A), a high facial ridge was seen in 26 patients, pars tensa perforation was found in 22 patients, and granulation edema in the epitympanum and mastoid was found in 10 patients (Fig. 1B). However, it was impossible to observe the lesions under the crust in some patients because of the tight adhesion between the crust and epithelium.
High-resolution computed tomography
High-resolution computed tomography scanning (General Electric Company, Fairfield, CT, USA) of the temporal bone revealed absence of the incus and malleus in 30 patients and only the head of the malleus remaining in 4 patients. Eighteen patients had a complete stapes, 30 had a high facial ridge (Fig. 2A), 18 had high-density shadows in the epitympanum and retrotympanum, 26 had high-density shadows in the tympanic antrum and mastoid, 16 had partial residual air cells, and 3 had dizziness with a large fistula in the horizontal semicircular canal on the affected side (Fig. 2B, C).
Techniques of revision surgery
All patients underwent a posterior ear procedure; removal of lesions from the tympanic antrum, mastoid, and residual air cells; ossicular chain exploration, mastoid obliteration with autogenous bone pate or retroauricular musculoskeletal flap; reconstruction of the epitympanum and retrotympanum cartilage; and plastic repair of the cavity of the concha. The secretions of the middle ear and mastoid cavity were taken for culture and drug sensitivity testing. All 34 patients (100%) had a narrow external auditory meatus orifice caused by non-plastic repair of the cavity of the concha in the first operation. A high facial ridge was seen in 30 patients (94%), a recurrent or residual cholesteatoma or huge retraction pocket in 28 (82%), and postoperative pathologic evidence of cholesteatoma epithelium and residual air cells with severe granulation, mucosal polyps, or edema in 16. Four patients had epithelialization of the tympanic mucosa and an immobile stapes during eustachian tube tamponade, including three patients with a large fistula in the horizontal semicircular canal that was treated with fistula repair (Fig. 3). Eighteen patients were treated with a partial ossicular replacement prosthesis (PORP) because of a complete and mobile stapes confirmed intraoperatively; of these patients, 4 who had adhesion in the tympanum were treated by cartilage-perichondrium tympanoplasty. Twelve patients received a total ossicular replacement prosthesis (TORP) because of loss of the structure of the stapes and mobile foot plate, including one patient who underwent labyrinthine fistula repair and two patients who underwent cartilage-perichondrium tympanoplasty for adhesion in the tympanum. Six patients with adhesion in the tympanum underwent both tympanoplasty with cartilage-perichondrium from the tragus and ossicular replacement prosthesis implantation. To prevent adhesion from redeveloping in the tympanum and to achieve reliable hearing after surgery, an aural NasoPore (Polyganics BV, Groningen, the Netherlands) and hyaluronic acid hydrogel (Shandong Saikesaisi Pharmaceutical Sales Co., Ltd., Shandong Province, China) were placed into the tympanum, and 1 mL of intratympanic dexamethasone was administered through the eustachian tube once a week for a total of 4 to 6 times.
The paired-sample t-test and one-way analysis of variance were performed using SPSS 20.0 (IBM Corp., Armonk, NY, USA), and differences were considered statistically significant at P < 0.05.
Dizziness and dry ear status
Of the 4 patients with a labyrinth fistula, three had preoperative dizziness and vomiting that disappeared completely on the first postoperative day, and they were able to carry out all activities of daily living. No preoperative or postoperative dizziness occurred in the other patient. All 34 patients achieved a dry ear by 6 to 8 weeks postoperatively (mean 5.8 ± 2.0 weeks) during a minimum 24-month follow-up; the earliest achievement of a dry ear was 4 weeks. Eight patients developed transient earache and otorrhea after a cold. After symptomatic treatment and local drug delivery, all symptoms were relieved within 1 to 2 weeks, and the patients achieved dry ear without intermittent or persistent otopyorrhea.
Hearing outcomes after revision surgery
In 30 patients, the mean air conduction (AC) and air–bone gap (ABG) were significantly lower 6 months after hearing reconstruction than preoperatively (P < 0.05). The 18 patients with a PORP and 12 with a TORP also showed statistically significant differences in the mean AC and mean ABG between the preoperative and postoperative periods (P < 0.05) (Table 1). However, there was no statistically significant difference between the mean preoperative AC and mean preoperative ABG between the 18 patients with a PORP and 12 patients with a TORP, nor was there a statistically significant difference between the mean postoperative AC and mean postoperative ABG (P > 0.05). In the four patients without hearing reconstruction, the mean preoperative airway threshold (500, 1000, 2000, and 4000 Hz) reached 80.2 ± 6.0 dB compared with 81.4 ± 5.8 dB after surgery, and the difference was not statistically significant (P > 0.05). The mean preoperative AC and ABG of the 6 patients with tympanum adhesion were 54.8 ± 6.8 and 34.6 ± 5.3 dB, respectively, with a statistically significant difference compared with 6 months postoperatively (38.4 ± 4.6 and 21.4 ± 4.8 dB, respectively; P < 0.05).
Culture and drug sensitivity test
Three patients were infected by Pseudomonas aeruginosa, 2 with Staphylococcus aureus, and 2 with Streptococcus faecalis; the remaining patients’ cultures were sterile. Appropriate antibiotics were given according to the results of the drug sensitivity test. One patient's P. aeruginosa infection was complicated by postoperative suppurative perichondritis of the auricle, which was cured after multiple sessions of debridement and dressing; only mild aural deformity remained.
The main purpose of mastoidectomy is to remove the lesion, maintain unobstructed drainage, and reduce intracranial and extracranial complications. In the present study, however, many complications and sequelae of the first operation remained because of the limitations of technology and conditions at that time. In 2012, the Group of Otology within the Society of Otorhinolaryngology Head and Neck Surgery, Chinese Medical Association issued guidelines  that promoted the diagnosis and treatment of otitis media. However, some of the 34 patients described in this paper had a long span of time between the first and second operations; the longest time span was 40 years. Moreover, most of the patients underwent operations at primary level II hospitals, and some of the operations were finished using gouge and low-resolution microscopy or even by visualization with the naked eye under the conditions at that time. Therefore, the occurrence of complications, cholesteatoma formation, and residual air cells was inevitable.
The primary goal of revision canal wall down mastoidectomy is to achieve a dry ear based on complete removal of lesions in the middle ear and mastoid.  An excessively open mastoid cavity requires a large external auditory meatus orifice for ventilation and drainage; otherwise, accumulation of epithelium in the mastoid cavity and local inflammation with granulation will readily occur. An excessively high facial nerve ridge can easily lead to a residual lesion of the retrotympanum and residual air cells of the posterior facial nerve, resulting in persistent or intermittent drainage. In this study, the main causes of otorrhea after the first operation were a narrow external auditory meatus orifice, high facial ridge, residual or recurrent cholesteatoma, and residual mastoid air cells. [8,13] Thus, to overcome these problems, mastoid cavity obliteration and plastic repair of the cavity of the concha were performed with autogenous bone pate or a retroauricular musculoskeletal flap on the basis of complete cleaning of the lesions to greatly reduce the cavity size and the postoperative time to achievement of a dry ear in this study. [13–15] The shortest time to a dry ear in this study was 4 weeks, while the longest was 8 weeks. Ramsey et al  reported a series of 60 patients who underwent mastoid cavity obliteration performed with autogenous bone pate or retroauricular musculoskeletal flaps and were followed up for 80 months with no recurrence of cholesteatomas. The total curative effect reached 90%. In the present study, all 34 patients achieved a dry ear in a short time; this outcome was related to plastic repair of the cavity of the concha according to the mastoid cavity size and appropriate mastoid cavity obliteration. Alves et al  reviewed 1017 cases and concluded that mastoid cavity obliteration with autogenous bone pate after canal wall down mastoidectomy can increase the rate of dry ear and improve patients’ quality of life.
In the present study, 30 patients underwent reconstruction of the posterior bony canal wall with autogenous bone pate or cartilage and ossiculoplasty, including 18 patients with a PORP and 12 with a TORP. The AC increased by a mean of 20.8 ± 6.3 dB, which was significantly different from the improvement in patients with a non-ossicular replacement prosthesis, and the curative effect was maintained for the >24-month follow-up. Li et al  reported 54 cases of revision canal wall down mastoidectomy and tympanoplasty with placement of an ossicular replacement prosthesis. During the 22-month follow-up, they found a mean AC improvement of 16.57 ± 11.96 dB, which was significantly different from the improvement in patients with a non-ossicular replacement prosthesis. Autogenous cartilage is taken from the cavity of the concha or tragus in such cases. This cartilage is easy to obtain, no additional incision is required, the cartilage exhibits good plasticity, and the height of the reconstructed tympanum is similar to that of the patient's original tympanum.
In the present study, six patients with adhesion in the tympanum underwent both tympanoplasty with cartilage-perichondrium from the tragus and ossicular replacement prosthesis implantation. To prevent adhesion from redeveloping in the tympanum and to achieve reliable hearing after surgery, an aural NasoPore and hyaluronic acid hydrogel were placed into the tympanum, and intratympanic dexamethasone was administered through the eustachian tube. Deng et al  used esterified hyaluronic acid material for tympanum packing in patients with adhesive otitis media, and the postoperative symptoms of hearing loss, tinnitus, and aural fullness were much less severe than those of patients in the other groups. In a study by Larem et al,  57 patients (60 ears) with adhesive otitis media underwent tympanoplasty using tragus cartilage combined with tympanostomy tube implantation and mastoidectomy. The postoperative mean bone conduction was significantly reduced. The ABG of 46 ears (84%) was <20 dB. Six patients with adhesive otitis media in the present study underwent secondary procedures (4 patients with a PORP and 2 patients with a TORP). The 6-month postoperative ABG was significantly decreased. However, compared with the findings reported by Larem et al,  the reasons for the poor postoperative hearing results were mainly the loss of the tympanic mucosa with granulation and scarring around the stapes after the operation.
No tympanoplasty was performed in 4 patients because of an immobile foot plate and epithelialization of the tympanic mucosa. The mean preoperative AC threshold and that of 6 months after eustachian tube tamponade were similar. Eustachian tube tamponade is an easy and convenient option for early achievement of a dry ear and prevention of secondary infection in the middle ear through the eustachian tube. Three patients with a lateral semicircular canal fistula were treated 10, 18, and 40 years after the first surgery, respectively. They had experienced increasing discharge from the diseased ear during the week before presentation. Of these three patients, two developed severe dizziness, nausea, vomiting, and stumbling, while the remaining patient developed mild dizziness without nausea or vomiting. These patients’ symptoms improved slightly after infusion of antibiotics and hormones. A large fistula was observed in the lateral semicircular canal by thin-slice computed tomography. A large amount of cholesteatoma epithelium was found in both the mastoid cavity and the lateral semicircular canal during the operation. After removal of this epithelium, we placed dexamethasone into the fistula and then used muscle and cartilage to fill it. Finally, we applied fascia and bone powder to the outside. On the first postoperative day, the patients’ symptoms of dizziness and stumbling significantly improved, and they were able to carry out all activities of daily living. This good outcome was achieved because the membranous labyrinth was connected to the environment, which allowed the pus and bacterial toxins to stimulate the membranous labyrinth and inner ear. One patient with a labyrinth fistula reported no dizziness. Intraoperative exploration showed that the membranous labyrinth was exposed, and lymphatic fluctuation was obvious in the fistula when the stapes foot plate was touched. Six months after fistula repair and implantation of a TORP, the AC had decreased from 55.0 to 36.5 dB. When performing labyrinth fistula repair, granulation and cholesteatoma epithelium around the fistula should be very gently removed after dexamethasone has been irrigated into the fistula to avoid damaging the membranous labyrinth and causing hearing loss. [18,19]
In conclusion, our study offers novel data on the clinical options for treatment of otorrhea after mastoidectomy that may affect intraoperative decisions. The absence of available data often makes it difficult to make clinical decisions. Earlier surgical failures of canal wall down mastoidectomy can be revised by a well-trained and experienced surgeon. A dry and safe ear is accessible in most patients, as is hearing preservation. However, after the failure of the first operation, some patients in the present study no longer believed in the effect of the operation, and others were not interested in a multi-phase operation, resulting in a small sample size. Thus, doctor–patient communication and follow-up should be paid close attention in further research to expand the sample size.
JL participated in the surgery of some patients,collected data and wrote the paper; HL participated in the operation and postoperative follow-up of some patients; XW participated in surgery and statistical analysis of some patients; XC participated in the operation and paper proofreading of some patients; YH was responsible for the overall design of the paper and was the surgeon of all patients. All authors had access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
This research was jointly supported by Zhejiang Provincial Natural Science Foundation of China, No. LY19H130003 (to YH), LY19H130004 (to HL) and Wenzhou Basic Scientific Research Project of China, No. Y20180091 (to YH).
Institutional review board statement
This retrospective study had been approved by the Ethical Committees of the First Affiliated Hospital, Wenzhou Medical University, China (approval No. 2008-05-02A11) on May 2, 2008.
Declaration of patient consent
The authors certify that they have obtained the patient consent forms. In the forms, patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity.
Conflicts of interest
The authors declare that they have no conflicts of interest.
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