A Comparative Study of Outcomes and Quality of Life in Canal Wall up Mastoidectomies and Canal Wall down Mastoidectomies.

Chronic Otitis Media (COM) of the squamosal type was primarily managed by performing a canal wall down mastoidectomy; however, the latter era otolaryngologist envisioned benefits in preserving the posterior canal wall. Our primary objective was to assess the disease specific quality of life following canal wall up (CWU) mastoidectomy and canal wall down (CWD) mastoidectomy surgery after a 6 month post-operative period. A prospective observational study was done from September 2017 to August 2018 where the charts of 380 patients from Christian Medical College, Vellore were reviewed. Details of patients above 18 years who had undergone the above surgeries for COM active squamosal disease from the period of January 2014 to December 2016; and had their post-operative follow up (average of 16 months) during the period of study were looked at. The CWU group had a significantly better disease-specific quality of life in the symptoms subscale than the CWD group (p value < 0.01). The CWU group showed a significant air-bone gap closure to 23.3 dB as compared to 27.7 dB in CWD (p value = 0.005). The recurrence rates were 4.5% (9 cases) in the CWU group and 3.9% (7 cases) in the CWD group, which was not statistically significant. Both CWU and CWD methods of mastoidectomy for COM squamosal type give comparable outcomes in terms of recurrence with the CWU group having a better disease-specific quality of life after surgery. Level of Evidence: 2a.

Keywords: Mastoidectomy; Cholesteatoma; Recurrence; Quality of life; Chronic otitis media

Chronic otitis media (COM) is a significant cause of acquired hearing loss, with a prevalence of 7.8% in the Indian population [[1]]. Although considered as a prime cause of preventable hearing in the developing world, about 60% of the affected people have a significant hearing impairment [[2]]. The term COM implies to a permanent abnormality in the pars tensa or pars flaccida caused as a sequela of acute otitis media, negative middle ear pressure or otitis media with effusion [[3]]. The active squamous type of COM warrants special attention in view its bone eroding properties and its propensity to lead to fatal complications. Treatment mandates clearance of the epithelium from the middle ear and mastoid which is often achieved by performing a mastoidectomy.

Mastoidectomy evolved from being a radical procedure where the external ear and mastoid were converted into large cavities which often required cavity care. Cavity related problems led surgeons to advocate posterior canal wall preservation which was later reverted to canal wall down procedures in view of reports of recidivism following posterior canal wall preservation [[4]].

The present-day otologist has a variety of techniques to choose from, each with its pros and cons, and each technique must be selected and tailored after careful to consideration of temporal bone anatomy and the extent of the disease. Surgery for cholesteatoma primarily aims at (a) eradication of disease (b) improving middle ear ventilation and preventing recurrent disease, (c) creating a dry, self-cleansing cavity and (d) hearing reconstitution.

Our study aimed to compare the short-term outcomes following canal wall up (CWU) and canal wall down (CWD) mastoid surgeries in patients with cholesteatoma. Our primary objective was to assess the quality of life, following 6 months post surgery. Our secondary objectives were to assess (a) for disease recurrence (b) re-perforations or retractions of the tympanic membrane, (c) the status of the ear canal, (d) post aural wound healing and e) the improvement in hearing threshold and air-bone gap closure after 6 months of follow up.

The institutional review and ethics board approval (IRB Min no: 10948 dated 07.11.2017) was obtained and the medical records of patients who underwent surgery for squamosal COM between January 2014 and December 2016 were reviewed. A prospective observational study of the patients operated in the aforementioned period was done from September 2017 to August 2018. Our inclusion criteria were patients above 18 years of age who were diagnosed with squamosal COM with cholesteatoma and underwent CWU/CWD surgery between January 2014 and December 2016 and came for follow up till August 2018 with a minimum follow up of 6 months post-surgery. We excluded patients with pure sensorineural hearing loss,revision surgeries, those with intracranial complications, and those who were lost to follow up.

Patients who satisfied the inclusion and exclusion criteria were invited to participate in the study and provided with the study information sheet. Recruitment into the study was done after obtaining a written informed consent. Their admission records and intra-operative records were examined and data were collected and entered on the data collection proforma.

The surgeries were carried out by 2 different units in ENT, one doing solely canal wall down surgeries and the other canal wall up surgeries. All surgeries were supervised by ENT specialists with similar experience for both types of surgery. The canal wall down surgeries comprised of performing a cortical mastoidectomy and exenteration of mastoid air cells, with the removal of facial bridge and ridge followed by tympanoplasty with or without ossiculoplasty and an adequate conchomeatoplasty. The canal wall up mastoidectomy comprised of performing a cortical mastoidectomy with thinning of the posterior canal wall with atticotomy and assessment of the sinus tympani and facial recess using an oto endoscope followed by tympanoplasty with or without ossiculoplasty.

Sample Size Calculation Sample size (N) was calculated using the following formula:

$$\raisebox{1ex}{$\text{N}=\left\{Z1-a/2\sqrt{2\overline{P\left(1-P\right)}}+Z1-\beta \sqrt{P_1\left(1-P_2\right)+\left(1-P_2\right)}\right\}2$}\!\left/ \!\raisebox{-1ex}{$\left(P1-P2\right)$}\right.2$$

Graph

where $\overline{\text{P}}=\raisebox{1ex}{$P_1+P_2$}\!\left/ \!\raisebox{-1ex}{$2$}\right.$ , P1—Proportion in the first group, P2—Proportion in the second group, α = Significance level, 1 − β = Power.

A minimum sample of 400 subjects (200 in each arm) was determined to obtain a difference of 10% between the recurrence rate of CWU and CWD group with 80% power and 5% significance level.

The post-operative assessment was done on the patient's visit to the ENT OPD by the primary investigator. Otoscopic and microscopy examination were done to assess the status of the tympanic membrane, adequacy of canaloplasty, meatoplasty status, and if there was any recurrence. We considered a residual disease when cholesteatoma or keratin pearls were detected within the first 6 months and recurrent disease was defined as the presence of cholesteatoma detected after 6 months, with previous documented disease-free visits.

Prior to selecting cases into each group, the medical records and operative notes were screened to assess the extent of cholesteatoma as per the pre-operative and intra-operative clinical records, to remove bias and confounding by indication. Both extensive diseases, as well as cases with limited involvement, were screened out, to ensure homogeneity between the groups. This implied that if an experienced otologist were to select either of the two methods and perform each technique in the standard way and minimize errors, we could expect a comparable rate of a successful outcome in both CWU and CWD groups.

The subjects were also asked to complete a quality of life questionnaire based on the 'Chronic Ear Survey.' (Fig. 1) [[5]]. It evaluated their level of activity restriction, ear discharge or pain following surgery, as well as medical resource utilization. The responses were graded on a scale of 1–5, with 1 being a good outcome and 5 being a poor outcome. Responses 1–3 were grouped in calculating overall positive response indicating improvement. Responses 4 and 5 were grouped to calculate overall negative response indicating worsening of symptoms after surgery.

Graph: Fig. 1 Chronic Ear Survey (Adopted from Nadol et al. [5])

The recruited patients underwent pure tone audiometric evaluation (PTA) (Inventis S.R.L Piano Plus, Italy) to assess the hearing levels at the follow-up visit. The pre-operative and post-operative audiograms were analyzed by taking an average of the pure tone threshold values at 500 Hz, 1000 Hz and 2000 Hz for air conduction and bone conduction and calculating the air-bone gap as the difference between the air conduction and bone conduction average values. Results were analyzed and each of the dependent variables was compared for both mastoidectomy groups.

The data was entered using EpiData software and analyzed using Statistical Package for The Social Sciences (SPSS) software. Categorical variables were summarized using counts and percentages. Quantitative variables were summarized using mean and standard deviation. A Chi-square test was used to compare the proportions between categorical variables. The Independent t-test was used to compare the means between two groups for normally distributed continuous variables and the Mann–Whitney U test was used for skewed variables.

There were 201 cases in the CWU group and 179 in the CWD group. Each underwent microscopic and audiological testing at follow-up. The age group spanned from 18 to 62 years with a mean age of 31.3 years with the majority of the study group being males. The average duration of follow-up was 16 months in the 2 groups, ranging from 6 to 48 months.

Disease Recurrence There were 9 cases (4.5%) of recurrence in the CWU group and 7 cases (3.9%) in the CWD group, which was not statistically significant (p value = 0.78). Six cases of recurrent perforation were seen in each group (Table 1), out of which 11 were seen in the parstensa and one in the attic region (CWD group).

Table 1 Post-operative occurrence of TM perforations and recurrent disease (CWU canal wall up, CWD canal wall down)

All the patients had a well-healed post aural scar with no post-operative wound infection or wound dehiscence. In the CWD group, 4 cases (2.2%) had a narrow meatus following meatoplasty, 2 had a high facial ridge (1.1%) and 12 had persistently discharging mastoid cavity (6.7%).

Hearing Outcomes The average pre-operative air conduction (AC) threshold was 51.8 dB in CWU and 52.4 dB in the CWD group and the groups were comparable. Hearing outcomes were assessed by comparing the average post-operative AC, BC, and ABG values of the 2 groups. The CWU group showed improvement in the average AC value to 40.1 dB, while the CWD group had an average AC of 44.8 dB, indicating statistically better hearing outcomes in the CWU group (p value = 0.003). There was also a statistically significant ABG closure in the CWU group (23.3 dB) than in the CWD group (27.7 dB) (p value = 0.005) (Table 2).

Table 2 Changes in post-operative hearing thresholds (AC air conduction, BC bone conduction, ABG air bone gap, CWU canal wall up, CWD canal wall down)

Granulations in the post-operative ears were noted in 19 cases of CWU and 17 cases of CWD and were comparable between the groups.

The results of the CES are summarized in Table 3.

Table 3 Quality of life questionnaire (CWU canal wall up, CWD canal wall down)

The CWU group had a better outcome in terms of lesser physical restriction, water restriction and improvement in the social interaction than the CWD group and this was found to be statistically significant. (p value < 0.05).

Among the symptom subscales assessed, the CWU group demonstrated significant improvement in subjective hearing improvement, the effect of hearing loss on daily activities, and ear discharge with specifications to frequency and odor than the CWD group. Symptom subscale for pain assessment showed comparable rates in both groups. In the medical resource utilization scale. The CWU group required fewer physician visits than the CWD group which was statistically significant (p value < 0.05), nevertheless the requirement for ear drops and oral antibiotics were comparable in both groups (Table 3).

As CWD was considered the gold standard for the treatment of cholesteatoma, earlier studies compared the outcomes of CWU, keeping the CWD results as a baseline. However, given a wide variation in the analyzed factors such as age group, surgeon expertise, various technical modifications used, duration of follow up, lack of distinction between residual and recurrent cases, and statistical methods used to calculate recidivism, a plethora of results were seen with CWU studies. Our study looked mainly at outcomes between the CWU and CWD in terms of residual/recurrent disease, hearing outcomes, and CES between the 2 groups. In our study, no cases of residual disease were noted before 6 months. This could be explained as findings were based on otoscopy and microscope examination alone, on an OPD basis. Ideally, a second look is advised following CWU surgeries to assess residual disease at 9–12 months post-surgery.

Our study had 9 cases (4.5%) of recurrence in the CWU group and 7 cases (3.9%) in the CWD group, which was not statistically significant.

Roden et al. [[6]] reported equal rates of recurrence in both groups, with a higher rate of residual disease in the CWU group (20.4%) as compared to the CWD group (4.7%) at a 5-year follow-up. In contrast, Stankovic et al. [[7]] reported recurrence rates of 7.8% in the CWU group and 22.1% in the CWD group, at 3 years follow up. The results from our study indicate that both techniques have comparable rates of recurrence at a 6 month follow up.

Nyrop in his follow up of patients up to 10 years, found that 70% of ears operated on by the CWU technique had developed a new cholesteatoma however CWD had a long-term recurrence rate of about 15% [[8]]. Incidence of recidivism in comparative studies done on CWU and CWD surgeries are summarized in (Table 4) [[9]–[12]].

Table 4 Previous studies comparing recidivism in CWU and CWD techniques for management of squamous COM (CWU canal wall up, CWD canal wall down)

A meta-analysis on the risk of cholesteatoma recidivism after CWU and CWD surgery reported a lower percentage of residual and recurrent disease after CWD (range 5–17%) compared to CWU surgery (range 9–70%), and the relative risk of recurrent or residual disease was 2.87 (95% confidence interval: 2.45–3.37) in CWU surgery [[13]]. Concerning hearing outcomes, the CWU group showed statistically better improvement in the average AC and ABG compared to the CWD group (p value < 0.01).

Tos et al. in his follow up of 740 post-operative patients at an average follow up of 9.3 years reported a significant air-bone closure in the CWU group than the CWU counterparts, however, their CWU group had a better pre-operative hearing threshold, to begin with [[14]]. On the contrary, Cook et al. found no significant differences between hearing results obtained by CWD versus CWU in a series of 153 cases, irrespective of ossicular reconstruction [[15]]. Regarding residual perforations, 12 cases (3.2%) had a residual perforation when examined at 6 months follow up, with an equal incidence of 6 cases in each group.

Mastoid cavity problems mandate lifelong maintenance and are a major concern following CWD surgery. In our present study, we had 4 cases (2.2%) with a narrow meatus following meatoplasty, 2 cases with a high facial ridge (1.1%), and 12 cases with a persistently discharging mastoid cavity (6.7%). Khan et al. noted a 6.7% incidence of meatal stenosis and 2.5% incidence of persistently discharging ear in 210 cases undergoing CWD at 12 years of follow up [[16]]. Kos et al. in his study of 338 ears over 24 years, reported a 5% incidence of a chronically wet ear; however, 95% of the ears had a well-epithelized cavity [[17]]. Jackson et al. also had a similar outcome of 2% cases with discharging mastoid cavity, from a study of 149 cases over 6 months to 13 years [[18]]. Attention to detail in following standard techniques of mastoid surgery will reduce errors and improve outcomes. A small mastoid cavity should be created where possible or mastoid obliteration techniques should be adopted.

Evaluation of COM outcomes has been limited to the measurement of recurrence rates and audiological measurements. These measures do not always correspond to the patients' symptoms or the patients' perception of their illness and its impact on their life. The inclusion of patient-based outcomes significantly enhances the dimensions of traditional outcomes analysis by providing a novel measurement tool. The inclusion of these data allows us to significantly improve the quality of care.

Nadol et al. developed the Chronic Ear Survey (CES) in 2000 [[5]], which is a disease-specific outcome survey and provides a reliable, valid measurement tool for assessing outcomes of surgical intervention in COM and allows the comparison of the many variables that can influence postoperative results. The use of such a patient-based survey also removes the bias of the operating surgeon and directly measures the impact of disease and intervention on the individual. It yields information on total disease-specific health, as well as on three subscores: Symptoms Subscore (SS), specific to symptoms of COM such as drainage from the ear; Activity Restriction (AR), which measures the impact of the disease on the patients' everyday activities, and Medical resource utilization (MR), which looks at factors such as usage of antibiotics and frequency of physician visits.

Quality of life following mastoid surgery is an indicator of the surgical outcomes in the context of the patient perspective. The present study is unique in that it is the only study that compares the QOL following 2 surgical techniques done for the same disease, using a disease-specific outcome measure. Hitherto studies have either applied general health questionnaires to COM patients or compared mucosal and squamosal COM with disease-specific questionnaires. Quaranta et al. reported comparable scores on QOL scores following CWU and CWD with mastoid obliteration [[19]].

In the physical activity restriction scale of the CES questionnaire, 85.6% of cases of CWU group reported lesser restriction as compared to 62.0% cases in the CWD group. In the water entry restriction scale, 68.7% of CWU cases reported lesser symptoms as compared to 34.1% in the CWD group. In the social interaction subscale, 90.5% CWU cases reported improvement as compared to 79.3% of CWD cases. The difference between the two groups was statistically significant with regards to these parameters, suggesting that the CWU technique fared better in these 3 outcome scales.

Among the symptom subscales assessed, the CWU group demonstrated significant improvement in subjective hearing improvement, the effect of hearing loss on daily activities, and ear discharge with specifications to frequency and odor than the CWD group. Symptom subscale for pain assessment showed comparable rates in both groups. With regards to the medical resource utilization scale, the CWU group required fewer physician visits than the CWD group which was statistically significant (p value < 0.05), nevertheless the requirement for ear drops and oral antibiotics were comparable in both groups.

This study included post-operative patients from 6 to 48 months after surgery, with a mean follow up of 16 months. The short duration of follow up may have made our recurrent disease rates appear more favorable, and such outcomes need to be studied for a longer period.

Both CWU and CWD methods of mastoidectomy for COM squamosal type give comparable outcomes in terms of residual and recurrent disease during early follow-up, however, the CWU group shows better outcomes in hearing improvement when compared to CWD group.

The CWU group had a significantly better disease-specific quality of life after surgery when compared to the CWD group, in terms of restriction in physical activity, water entry into the ear, the effect on social interaction, subjective hearing improvement and frequency of physician visits with comparable results in the use of both oral and topical antibiotics.

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The authors declared that they have no conflict of interest.

IRB No 10948.

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