Microscopic versus endoscopic stapes surgery—a meta-analysis study

Abstract

Background

The traditional approach for viewing middle ear structures during ear surgery is still the microscope, which provides both hands’ flexibility and binocular vision. The requirement for a clear, direct vision of the working zone is its primary disadvantage. The procedure was modified for the microscope by using an end-aural approach, drilling the bone canal, and then moving the patient and surgeon. However, the microscope has successfully demonstrated that it is the preferred tool for stapedectomy.

Objective

To compare endoscopic and microscopic interventions in stapes surgery regarding intraoperative and postoperative outcomes.

Patients and methods

The review was a meta-analytic and systematic review that included randomized controlled trials (RCT), case series, and retrospective studies which studied the comparison of microscopic and endoscopic stapes surgery; 15 articles published between 2014 and 2020 were included in our study.

Data sources

PubMed, Embase, and Cochrane Library were searched for studies published up to 2020. The inclusion criteria comprised randomized controlled trials, cohort studies, and case–control studies comparing microscopic and endoscopic stapes surgeries.

Results

Our results showed that the injury to the chorda tympani nerve was significantly higher in the microscopic group versus the endoscopic group. And also, as regards the operative times, it was significantly longer in the microscopic group versus the endoscopic group. But there is no significant difference as regards pain, dizziness, perforation of the tympanic membrane, delayed conductive hearing and postoperative air–bone gap improvement, and taste disturbance between both groups.

Conclusion

Technologically, safely, and promisingly, endoscopic stapes procedures are possible. All things considered, our research shows that both microscopic and endoscopic stapes surgery yields good audiological outcomes. A little amount of data, however, points to a decreased likelihood of chorda tympani injury and taste disturbance when using an endoscope. With comparable side effects to microscopic stapes surgery (pain, tympanic membrane perforation, taste disturbance, dizziness, and delayed conductive hearing), endoscopic stapes surgery seems like a feasible substitute. Endoscopic stapes surgery was found to need shorter operating times. In comparison to endoscopic groups, the postoperative air–bone gap increased considerably in the microscopic group. All of the studies consistently indicated better sight with the endoscope. This meta-analysis of the available data bolsters the application of endoscopic methods in stapes surgery.

Background

Since it provides easy access and wide vision, the typical strategy for middle ear procedures is the microscopic approach. The requirement for an unobstructed and direct view of the operating space is the primary disadvantage [1].

With reliable results, the microscope has been demonstrated to be the preferred instrument for stapes surgery [2].

Endoscopic approach in middle ear surgery has started 50 years ago or more and has presented an alternative for microscope in surgery of the middle ear [3, 4].

It was initially used as an additional tool in cholesteatoma surgery to help in the operation. Shortly after, the microscope has been replaced by endoscope entirely, as in stapes surgery [5,6,7].

With less drilling done in the external canal and less handling and manipulation of the chorda tympani, the use of an endoscope can offer a close-up view of the footplate. The wide-field perspective, enhanced illumination, and magnified image allow for safer operation of the footplate, chorda tympani, and stapes system. In their comparison of endoscopic and microscope visualization, Bennet et al. discovered that endoscopic visualization is superior from every angle [8, 9].

On the other hand, the endoscope has its disadvantages such as single hand use and loss of three-dimensional vision. The heat of endoscopic illumination can damage the chorda tympani nerve and can affect hearing [10].

By searching the database, multiple studies have been found comparing endoscopic and microscopic interventions. Most of the reviews have no meta-analysis. The most recent systematic review was published in 2020, and it included studies till 2018 [11].

In our study, we will search databases for recent studies additionally to have the highest evidence of the better intervention.

Main text

Patients and methods

Aim of the work

The aim of the work is to evaluate the intraoperative and postoperative results of stapes surgery using endoscopic and microscopic approaches. The chorda tympani damage and postoperative air–bone gap (ABG) are the main results. The average operating times, intraoperative drum membrane perforation, and postoperative problems such as discomfort, taste disturbance, dizziness, and delayed conductive hearing are secondary outcomes.

Criteria for considering studies for this review

Studies of the following types will be included in our systematic review: case series, randomized controlled trials (RCT), and retrospective studies that looked at endoscopic and microscopic stapes surgery.

Types of participants

Participants in selected articles of our study will be adults above 16 years old with diagnosis of otosclerosis.

Types of interventions

The types of interventions are as follows: microscopic and endoscopic stapes surgery. All articles will be reviewed and will be included if microscopic or endoscopic stapes surgery was done without any other treatment strategy.

Methodology for finding studies

Using the Virtual Health Library, Google Scholar, Cochrane Library, and PubMed, Clinical Key, Scopus, EMBASE, and LILACS as electronic databases, we will look for pertinent publications. To conduct this review, the phrases “Microscop*,” “Endoscop*,” “Stapes,” stapedectomy, and stapedotomy will be used to search the register. Every trial that has been identified will have its review articles and bibliographies examined for other references that might include other kinds of studies.

Methods of the review

Locating and selecting studies

The articles found by applying the search method will be examined, and those that seem to meet the requirements for inclusion will be fully retrieved. The study has to provide data on at least one of the outcome measures.

Included

This study will include published papers about stapedectomy or stapedotomy published on the last 20 years (between 2000 and 2020). All participant must be surgically operated either microscopically or endoscopically. The articles must report the intra operative details and/or postoperative outcome.

Excluded

The following will be excluded: review articles or case report studies, studies published before 20 years, studies discussing non-surgical treatment of otosclerosis, and studies not reporting outcomes after intervention.

Data extraction

The writers will do their own independent data extraction.

Statistical considerations

Review Manager will be used to integrate the results from the included studies.

Measures of outcome

The chorda tympani nerve damage and the average postoperative air–bone gap (ABG) are the main results. The mean operating times, intraoperative tympanic membrane (TM) perforation, and postoperative pain, taste disturbance, and dizzy problems are secondary outcomes.

The funnel plot approach will be used to look for evidence of publication bias

A funnel plot is a straightforward scatter plot that compares the estimated intervention effects from individual studies to a metric representing the size or precision of each research.

Results

One thousand three hundred seventeen studies were found via the database search, according to our meta-analysis. There were 160 studies left after duplicates were eliminated. Fifteen studies published between 2014 and 2020 were included in our investigation after undergoing full-text article review. Thirteen of the fifteen investigations were retrospective, two were prospective, and one was a case series.

In terms of the overall patient demographics, our analysis revealed that 926 cases in all, with a mean age of 37.4 years (SD ± 9.72) and a male to female ratio of 453:433, were included. Four hundred ninety endoscopic procedures and 436 microscopical procedures were performed, and the follow-up periods ranged from 12.6 to 16.6 months, with an average of 14.6 months (Figs. 1, 2, 3, 4, 5, and 6).

Fig. 1

Forest plot for operative times

Fig. 2

Forest plot for handling to the chorda tympani nerve

Fig. 3

Forest plot for taste disturbance

Fig. 4

Forest plot for pain

Fig. 5

Forest plot for perforation of the tympanic membrane

Fig. 6

Forest plot for dizziness

As regards the air–bone gap, 11 studies included in our study showed that the postoperative air–bone gap become higher significantly in the microscopic group vs the endoscopic group (p-value 0.044, I² (inconsistency) 46.55%, 95% CI for I² 0.00–73.41) (Tables 1, 2, 3, 4, and 5).

Table 1 Study characteristics

Table 2 Patient’s characteristics

Table 3 Statistical analyses for postoperative air–bone gap

Table 4 Statistical analysis for postoperative perforation of the tympanic membrane

Table 5 Meta-analysis for delayed conductive hearing loss

Discussion

Middle ear surgery performed using endoscopy has been associated with fewer problems after surgery, easier and less invasive access to the field, and improved imaging of “hidden” structures.

Therefore, it is probable that endoscopic utilization will result in lower rates of postoperative side effects and higher rates of successful stapedotomies (postoperative ABG ≤ 10 dB or hearing restoration).

As regards operative times, 12 studies included showed that the operative time is significantly longer in the microscopic group vs the endoscopic group (p-value < 0.0001, I² (inconsistency) 92.39%, 95% CI for I² 88.57–94.93).

In contrast to the mean microscopic time of 73.1 min (95% CI, 52.7–93.4), the mean pooled endoscopic time was 69.2 min (95% CI, 60.7–77.8). The two groups’ mean difference value was 3.9 min, with endoscopy coming out on top. The standard mean difference for operating time in a random effects meta-analysis was − 0.64 min, indicating that there was no statistically significant difference between the groups.

Regarding improvement of air–bone gap postoperatively, we found that the 11 studies included showed that there was better outcomes in the microscopic vs endoscopic groups (p-value 0.044, I² (inconsistency) 46.55%, 95% CI for I² 0.00–73.41). The primary outcomes were postoperative ABG < 10 dB: OR = 1.80 (95% CI: 0.96 to 3.38), ABG = 11 dB to 20 dB: OR = 1.49 (95% CI: 0.76 to 2.93), and ABG > 20 dB: OR = 2.51 (95% CI: 0.77 to 8.22). Manna et al. demonstrated that there was no statistically significant difference in the mean improvement in ABG between the two groups. Additionally, Nikolaos noted that no statistically significant difference was detected between the endoscopic and microscopic ways of performing stapes surgery in terms of achieving a postoperative ABG of up to 10 dB and consequently in terms of surgery success rates.

As regards the injury to the chorda tympani nerve, our metanalysis showed that the 15 studies included reported about the handling to the chorda tympani nerve and showed insignificant differences between the microscopic group vs the endoscopic group (p-value 0.1502, I² (inconsistency) 32.25%, 95% CI for I² 0.0–67.67).

In our study, fifteen articles reported about the postoperative taste disturbance during endoscopic and microscopic stapes surgery and showed insignificant differences between the microscopic and the endoscopic groups (p-value 0.1903, I² (inconsistency) 28.61%, 95% CI for I² 0.00–66.85).

Patients undergoing microscopic surgery had a higher risk of postoperative dysgeusia (p = 0.007 and p < 0.05, respectively), according to Surmelioglu et al. and Gulsen and Karatas [17, 25]. This was consistent with patients having their chorda tympani nerve manipulated during surgery. In the surgical follow-up, dysgeusia was subjectively evaluated based on the patient’s complaint of taste changes.

According to our findings, 15 publications discussing postoperative tympanic membrane perforation in our investigation revealed negligible differences between the microscopic and endoscopic groups (p-value = 0.9558). Following a review of 14 research, Pauna et al. [27] reported that there was no difference in the incidence of tympanic membrane perforation or facial paralysis between the two groups in the five comparative studies that were included.

In terms of pain, our analysis revealed that the 15 included studies, which discussed postoperative discomfort, revealed negligible differences between the groups under microscopic and endoscopic examination (p-value 0.6259, I² (inconsistency) 0.0%, and 95% confidence interval (CI) for I² 0.00–77.87). Based on our findings, Koukkoullis et al. [11] evaluated the postoperative pain based on four investigations, which was the same for endoscopic and microscopic stapes surgery with no significant difference.

But, conversely, Manna et al. [28] revealed that among stapes surgeries, there was a statistically significant reduction in postoperative pain in the ESS group compared to the MSS.

Regarding the dizziness, we found that the 15 studies included reported about the dizziness, which showed insignificant differences between the microscopic and endoscopic groups (p-value 0.8563, I² (inconsistency) 28.61%, 95% CI for I² 0.00–41.10).

Another significant problem that significantly impacted the patients’ quality of life following surgery was postoperative dizziness. Theoretically, patients undergoing ESS procedures will experience less postoperative dizziness since there would be less manipulation of the stapes footplate due to improved visibility. Nevertheless, Mitchell and Coulson’s investigation did not reveal any notable differences. Given the aforementioned results, they hypothesize that, despite the minimally intrusive method, the endoscope’s temperature may still have an impact on the inner ear, with an unknown cause [29].

In agreement with our results, Koukkoullis et al. [11] showed that there was no statistical difference between both groups as regards dizziness.

As regards delayed conductive hearing, 15 studies included illustrated the delayed conductive hearing shows insignificant differences between the microscopic and endoscopic groups (p-value 0.6324, I² (inconsistency) 28.61%, 95% CI for I² 0.00–77.49). Koukkoullis et al. revealed that the endoscopic method’s hearing results are comparable to those obtained under a microscope, which is in line with our findings.

Conclusion

Technologically, safely, and promisingly, endoscopic stapes procedures are possible. All things considered, our research shows that both microscopic and endoscopic stapes surgeries yield good audiological outcomes. A little amount of data, however, points to a decreased likelihood of chorda tympani injury and taste disturbance when using an endoscope. With comparable side effects to microscopic stapes surgery (pain, tympanic membrane perforation, taste disturbance, dizziness, and delayed conductive hearing), endoscopic stapes surgery seems like a feasible substitute. Endoscopic stapes surgery was found to need shorter operating times. In comparison to endoscopic groups, the postoperative air–bone gap increased considerably in the microscopic group. All of the studies consistently indicated better sight with the endoscope. This meta-analysis of the available data bolsters the application of endoscopic methods in stapes surgery.