Endoscopic Assessment of Cholesteatoma Following Microscope Assisted Tympano: Mastoidectomy

Introduction

Complete surgical removal of cholesteatoma has been traditionally performed by microscopic approaches. In recent years, use of endoscopes in middle ear surgery is gaining increasing importance. The wide field view offered by the endoscopes in comparison to the narrow field of view of the binocular microscope enables a surgeon to see and dissect around corners, thereby exposing ‘hidden recesses’ of the middle ear which can be useful during cholesteatoma surgery. To identify remnant cholesteatoma in difficult access sites of the middle ear cleft using endoscopes following a microscope assisted mastoidectomy. A cross sectional study was conducted in patients who were clinically diagnosed with cholesteatoma. Patients were subjected to High Resolution Computed Tomography of the temporal bone and pre-operative audiological tests. Mastoid exploration was performed microscopically followed by endoscopic evaluation and clearance of disease in the same setting. Patients were then followed up post-operative and endoscopically evaluated to look for any remnant disease. A total of 45 patients were included, all of which underwent microscopic assisted mastoidectomy. Remnant cholesteatoma was discovered in 15 out of 45 cases (33%) distributed in the hidden areas; in the region of sinus tympani 9(60%), anterior epitympanum 4(27%), hypotympanum 1(7%) and tip Cells 1(7%). It can be concluded that endoscopes have a definite role in evaluation and complete surgical clearance of cholesteatoma particularly from the hidden areas of middle ear cleft which would have otherwise been missed by the straight line view of a microscope thereby grossly reducing the rate of remnant disease.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-023-04263-6.

Background

Cholesteatoma has proven to be a formidable enemy as it can erode bone, destroy ossicles, and invade inner ear or facial canal causing facial paralysis, vertigo and sensorineural hearing loss and intracranial complications. Its eradication remains a noteworthy challenge for otologists. Microscopic surgery has been the gold standard for surgeries of the middle ear and mastoid. However, incomplete removal leading to residual disease may happen even after meticulous removal under operating microscope, due to presence of cholesteatoma in hidden areas, which are not readily visualized by straight-line vision of the microscope. With the introduction of endoscopes in the 1990s, the concept of minimally invasive approach in middle ear surgery for eradication of cholesteatoma began. Endoscope has now found a definitive, accepted place in ear surgery [1]. The virtues of being able to view and access the challenging recesses of the middle ear are well documented, where endoscopes serve as an adjunct to standard microscopic approach. Endoscopic middle ear surgery gives better visualisation of tympanic structures and direct visual control of hidden areas such as retro tympanum, pro tympanum and anterior epitympanic spaces. Thus, a cross sectional study was conducted where endoscopes will be used to assess residual cholesteatoma using standard microscopic methods after completion of standard mastoid exploration.

Methods

After Institutional Review Board approval, the study was conducted in the Department of Otorhinolaryngology, Maulana Azad Medical College and associated Lok Nayak Hospital, New Delhi.

The study was conducted from November 2019 to November 2021. Patients of age above 5 years clinically diagnosed with squamosal type of chronic otitis media attending Out Patient Department (OPD) of ENT of Lok Nayak Hospital, New Delhi were included in the study. However, patients having complications, congenital cholesteatoma and those who had prior ear surgery were excluded.

Methodology

Written informed consent was taken from all patients. Patients clinically diagnosed with cholesteatoma were subjected to High Resolution Computed Tomography of the temporal bone (HRCT) and pre operative audiological tests like Tuning fork tests and Pure Tone Audiometry (PTA). Patients having extensive disease progression on High Resolution Computed Tomography of the temporal bone (HRCT) were then evaluated further with the basic blood investigations and pre anaesthetic check up for surgery.

Equipment

Zeiss® operating microscope (model OPMI 1) was used to perform microscopic dissection of cholesteatoma in the middle ear. For endoscopic evaluation of the middle ear 0 degree and 30-degree, 4 mm and 2.7-mm wide, 18 cm length, rigid endoscope along with medical monitor, light source, a high definition 3-chip video camera and recorder of Karl Storz® were used.

Operative Technique

All patients underwent mastoid exploration with clearance of cholesteatoma which was accompanied with type 3c or type 3a tympanoplasty based on the ossicular status assessed intraoperatively. The first surgeon performed the surgery and upon reaching a satisfaction level with complete removal of cholesteatoma by operative microscopy, endoscopes were used to assess disease clearance by a second surgeon. Endoscopes with various observation angles (0 and 30 degrees) were introduced either transcanal or transmastoid. The surgeon tried to look for any epidermal remnant in all the difficult to access areas. Findings were recorded and photographed by a second surgeon. The following areas were specifically inspected: sinus tympani, anterior epitympanic recess, Eustachian tube, and hypotympanum. Upon the discovery of epidermal remnant further dissection and clearance was carried out using endoscopes by the second surgeon in the same sitting. Patients were then reviewed post-operatively after and endoscopically evaluated to look for recurrence or residual disease.

Results

A total of 45 patients were included in our study. Patients of the age above 5 years were included in the study with maximum patients lying in the age group 21–30 years with the mean age group being 22. There were 27 (60%) males and 18 (40%) females. All patients in the study presented with the symptoms of otorrhea 45(100%) or a combination of other symptoms together which included decreased hearing 36(80%) and earache 11(24%).

All the patients underwent Hight Resolution Computed Tomography of the temporal bone and based on their findings were classified as having unilateral or bilateral otomastoiditis with cholesteatoma formation and/or with ossicular erosion. The finding of unilateral otomastoiditis with ossicular erosion on Computed tomography accounted in 18(40%) followed by otomastoiditis with cholesteatoma formation in 16(35%) bilaterally and 11(25%) unilaterally.

Patients were subjected to pure tone audiometry after which they were classified on the basis of air bone gap (ABG). Maximum negative Rinne’s test was performed noted with 512 Hz tuning fork correlating with PTA findings of 20–40 dB hearing loss. Patients also underwent Weber’s testing of which 26 were found to have Weber’s lateralized to left ear and 8 to right consistent with the side of the diseased ear. The Absolute Bone Conduction tests in all patients was not found to be shortened.

All patients underwent modified radical mastoidectomy (MRM). It was accompanied with type 3c or type 3a tympanoplasty based on the ossicular status assessed intraoperatively. Majority of the patients 27(60%) underwent type 3c tympanoplasty.

Intra-operatively, cholesteatoma was commonly encountered in the region of middle ear cleft also found concurrently within the mastoid antrum in all cases along with extent to the different sites as mentioned below.

Extent exclusively to the mesotympanum accounted to 22(51%) patients followed by combined involvement of mesotympanum & epitympanum in 19(44%) patients and only 2(5%) patients had additional hypotympanum involvement (Fig. 1).

Fig. 1.

Location of Cholesteatoma within the middle ear cleft

After maximal clearance of cholesteatoma microscopically, an endoscope was introduced to assess the presence of any remnant disease. 15(33%) patients were found to have epidermal remnant whereas 30(67%) did not (Figs. 2, 3). The epidermal remnant was removed in the same sitting endoscopically using routine middle ear instruments.

Fig. 2.

Endoscopic findings of remnant cholesteatoma

Fig. 3.

Sites of remnant cholesteatoma

Patients found having remnant cholesteatoma were divided on the basis of location of the remnant disease. Out of 45 subjects, 15(33%) were found to have remnant cholesteatoma. remnant cholesteatoma was discovered in the region of sinus tympani 9(60%), anterior epitympanum 4(27%), hypotympanum 1(7%) and tip Cells 1(7%).

In all the subjects that were included in the study, none had any extracranial or intracranial complications pertaining to the ear like labyrinthitis, facial nerve palsy, brain abscesses etc. (Figs. 4, 5, 6, 7, 8, 9).

Fig. 4.

Endoscopic view of Left middle ear using a 30-degree rigid endoscope showing cholesteatoma sac (black arrow) in the region of sinus tympani

Fig. 5.

Endoscopic view of left middle ear using a 30-degree rigid endoscope following complete surgical clearance of the region of sinus tympani

Fig. 6.

Endoscopic view of left middle ear using a 0-degree rigid endoscope showing remnant cholesteatoma (black arrow) in the region of tip cells

Fig. 7.

Endoscopic view of left middle ear using a 0-degree rigid endoscope showing remnant cholesteatoma (black arrow) in the region of anterior epitympanum

Fig. 8.

Endoscopic view of left middle ear using a 30-degree rigid endoscope inferior hypotympanum cell remnant cholesteatoma

Fig. 9.

Endoscopic view of left middle ear using a 30-degree rigid endoscope after clearance of the disease from inferior hypotympanum cell

Discussion

All middle ear cholesteatoma require surgical management. The objectives of surgical management of cholesteatomatous chronic otitis media include complete eradication of the disease, isolating the middle ear from the exterior (anatomically), obtaining a dry cavity in the middle ear lined by a viable mucoperiosteum with proper aeration with a stable, fine, and mobile eardrum in a good position. In addition, the recovery or preservation of hearing (functional) by reconstructing the tympanic membrane and mechanism of sound transmission is sought. One can opt for a closed technique with reconstruction of the middle ear and posterior canal wall or an open technique with meatoconchoplasty [2].

Majority of otological procedures are being performed under an operating microscope, which provides the surgeon with stereoscopic vision and bimanual handling. However, the use of microscopes may not be sufficient to view the hidden areas of the middle ear cavity such as sinus tympani, epitympanic recesses, or to confirm the circumference of the perforation, especially in the presence of a protruding anterior canal wall [3]. For this reason, recently, there has been an increase in the use of the endoscope for otological procedures conventionally performed under a microscope, such as tympanic membrane reconstruction, repair of ossicular chain defects, cholesteatoma, and stapes surgery.

Overtime, microscopes have underwent improvements in the areas of lighting and magnification, however owing to their defined lines of sight which can be constrained by a distortion in anatomy of the external auditory canal leading to areas within the surgical field that are difficult, if not impossible, to visualise [8]. This inadequate exposure of the surgical field usually leads to residual disease and potential recurrence [12]. The usual sites of residual disease in the middle ear cleft are sinus tympani, anterior epitympanum, tip cells, hypotympanum, sinodural angle and eustachian tube area. The sinus tympani and facial recess areas are difficult to access using a microscope even after adequate removal and lowering of the posterior canal wall to maximum extent. Similarly the anterior epitympanum and pro tympanum can be difficult to visualise even after removing the lateral attic wall.

Endoscopes can aid in these situations as it has the ability to look at angles and also the external call wall diameter is not a limiting factor. With endoscopes, the line of sight can be moved closer to the surgical field allowing for more complete surveillance. In addition, endoscopes allow visualisation around structures, which is not possible with a conventional microscope and is greatly augmented with angled endoscopes. The utility of endoscopes has been demonstrated in many studies that show reduced residual disease rates due to increased visualisation. Unanticipated residual disease after microscopic dissection is found between 20 and 50% of the time using endoscopes with the highest percentage observed in the sinus Tympani [6, 8].

The successful use of endoscopes to assist in cholesteatoma removal during conventional otomicroscopic surgery [4] is well documented in the literature and the findings of residual cholesteatoma were consistent with those in the previous published articles with sinus tympani being the most common area of residual disease.

Bhavika V et al. conducted a study to evaluate the use of endoscope in identifying the cholesteatoma remnant at the time of primary surgery with the operating microscope. 116 patients with acquired cholesteatoma were operated on. Out of 116 patients operated with the microscope, 13 had a cholesteatoma remnant at the end of surgery which was missed by the microscope but identified with the otoendoscopy [4].

Kevin X Mc Kennan in his study performed an endoscopic ‘second look’ mastoidoscopy to rule out residual epitympanic/ mastoid cholesteatoma. Of the 12 cases examined endoscopically, 2 had residual cholesteatoma, one each in mastoid cavity and epitympanum [5].

Badr-El-Dine in 2002 performed a study and included a series of 82 canal-wall-up (CWU) surgeries and 10 canal-wall-down (CWD) surgeries for cholesteatoma. In the primary surgery after completion of microscopic cleaning, the endoscope detected residual disease in 22.8%. Sinus tympani was the most common site of intraoperative residuals in both CWU and CWD groups, followed by the facial recess and the medial part of the scutum in the CWU cases. However, despite the use of the endoscope in conjunction with the operating microscope, 100% eradication of the disease still could not be achieved; however, the use of endoscopes did reduce the residual cholesteatoma rate [6].

Marc Bennett et al. in 2018 in his case series involved the prospective enrolment of 110 consecutive cholesteatoma patients over a 2-year period. All patients underwent cholesteatoma surgery using microscopy. At the end of dissection and before reconstruction, the middle ear of the same patients were visualised with straight and angled endoscopes for residual cholesteatoma. Intraoperative endoscopic surveillance was able to detect residual cholesteatoma in 18 patients. The most common areas of cholesteatoma residual involvement were the mesotympanum (95.5%), epitympanum (78.2%), sinus tympani (47.3%), mastoid (27.3%) and hypotympanum (21.8%), eustachian tube (10.9%), and supratubal air cells (9.1%) [7].

Ayache et al. in 2008 published a large retrospective review of 350 patients who had surgery for cholesteatoma. After excision of the disease microscopically, the cavities of the middle ear were examined by otovideoendoscopy, Endoscopes were introduced and revealed residual cholesteatoma in 44% of cases overall, and in a staggering 76% of cases where cholesteatoma involved the retrotympanum. He concluded that analysis using otoendoscopy reduces the incidence of residual cholesteatomas by identifying lesion extensions that are overlooked under otomicroscopy [8].

Sajjadiin 2013 published a large retrospective review of 249 primary cholesteatoma who underwent otologic surgery using the microscopic techniques. Closed cavity technique was performed in 182 out of the 249 cases. Otoendoscopes were used to check for any cholesteatoma remnants. For the 182 cases receiving primary closed cavity technique, endoscopy revealed a 22% incidence of cholesteatoma (40 patients). The distribution of the residual cholesteatoma was 55% in the sinus tympani (22 patients), 30% in the attic (12 patients), and 15% in the cog areas (6 patients). He stated that endoscopic resection of cholesteatoma following detailed microscopic surgery has reduced the incidence of residual cholesteatoma detected on second-look surgery to a very low rate of 9.7% in closed cavity cases. Furthermore, endoscopes significantly reduced the need to open the mastoids during second look operations [9].

Shin-Ichi Haginomori et al. conducted a retrospective case-series study where 85 ears with fresh extensive cholesteatomas were operated upon. Out of which, 18 had residual cholesteatomas when examined endoscopically. For an overall incidence of 21%, 6 cholesteatomas were located in the epitympanum (33%), 3 in the sinus tympani (17%), 3 in the antrum (17%), 2 on the stapes (11%), 2 on the tympanic membrane (11%), 1 on the tympanic portion of the facial canal (6%), and 1 just under the skin of the external auditory canal (6%) [10].

L. Gaillardin et al. conducted a study in 109 patients which included 113 CWUT procedures with 4 patients (3.5%) having bilateral cholesteatoma. Residual cholesteatoma was found in 29 cases in 77 s look procedures: i.e., 25% of the series as a whole. In 90% of cases, the location of the residual was found to be that of the primary cholesteatoma. This suggests that the residual is induced by insufficient local resection of the epidermal matrix [11].

Bo Li et al. performed a systematic review and meta-analysis in which 13 studies were included. The pooled results showed that EES reduced the residual lesion rate and postoperative recurrence risk in patients with middle ear cholesteatoma [12].

Residual disease tends to develop in sites where access to cholesteatoma is impeded in primary surgery [13]. Residual middle ear cholesteatomas account for most of the cases of recurrent disease. The limited role of microscopy in the visualization of tridimensional anatomic alterations of the temporal bone led to the use of endoscopic examination as an additional tool in the realm of ear surgery. Endoscopy has significantly aided in the management of chronic cholesteatomatous otitis media and in the prevention of recurrent disease [14].

Tables 1 and 2 are a compilation summary of the data procured from previous conducted studies along with the present study which brings us to a conclusion that despite meticulous microscopic dissection of cholesteatoma, residual disease is inevitably left behind.

Table 1.

Number/percentage of endoscopically detected residual cholesteatoma following microscopic primary surgery

	Bhavika V et al	Sajjadiin	L. Gaillardin et al	Marc Bennett et al	Shin-Ichi Haginomori	Badr-El-Dine	Kevin X Mc Kennan	Present study
Total np of cases	116	182	113	110	85	92	12	45
No. of cases with residual	13	47	29	18	18	21	2	15
% of no. of cases with residual	11.2%	32%	25%	19.5%	21.1%	22.8%	16.6%	33%

Table 2.

Sites of residual cholesteatoma as detected by the endoscope during the primary surgery (in percentage of the total cases operated)

Sites of residual cholesteatoma	Bhavika V et al	Sajjadiin	L. Gaillardin et al	Marc Bennett et al	Shin-Ichi Haginomori	Badr-El-Dine	Kevin X Mc Kennan	Present study
Sinus tympani	6%	11.6%	0.9%	17%	3.5%	9.7%	0	20%
Epitympanum (AES and PES)	1.7%	6.5%	11.9%	5.8%	7%	1.08%	8.3%	8.8%
Hypo-tympanum	0	0	0.9%	1.9%	0		0	2.2%
Facial recess	3.4%	0	4.58%	0	0	1.08%	0	0
Mastoid tip	0	0	0	0	0	0	0	2.2%
Around the ossicles	1.7%	0	0.9%	0	2.3%	1.08%	8.3%	0
Around cog	0	3.2%	0	0	0	0	0	0
Facial canal	0	0	0	0	1.17%	0	0	0

On comparison, findings of the present study are found to be relatively consistent with those of previously conducted studies in terms of percentage residual disease left behind ranging from 1 to 33% (approximately). Our study revealed remnant disease in 15 (33%) patients. The preponderance sites of remnant cholesteatoma was carefully followed through and it was noted that sinus tympani was found to be the most commonly encountered site ranging from 6 to 20% (approximately) followed by the epitympanum and less commonly in facial recess, areas around the ossicles, hypotympanum and seldomly in areas around the cog, facial canal and tip cells (as seen in our study).

With the above data, one can state that employment of endoscopes after microscopic assisted mastoidectomies have shown to be beneficial. Endoscope can serve as an adjunct to scan through these areas endoscopically which will prevent disease to be left behind in such anatomically challenging recesses which are often hidden from the straight line view of a microscope. When endoscopes are being used to explore a microscopically operated mastoid cavity, areas of special reference should include sinus tympani, epitympanum, hypotympanum, facial recess, areas around the ossicles and tip cells.

Thomassin et al. compared endoscope-aided to traditional ear microsurgery and found reductions on the rates of residual cholesteatoma from 47 to 6% in a group offered intraoperative endoscopy followed up for 19 months [15].

Thus, one can infer that in addition to the consistent findings of residual cholesteatoma revealed via endoscopic evaluation in these areas despite adequate microscopic mastoidectomy, endoscopes have shown to address the target pathology transcanal with minimal dissection [16].

Although, endoscopic ear surgery (EES) has been rapidly evolving, expanding its boundaries from the middle ear to the lateral skull base. Nonetheless, the advantages of the endoscopic technique are associated with a number of intrinsic limitations. With the complementary use of microscopic and endoscopic techniques, one should be aware of the limits and advantages of both techniques and use them separately or combined, taking into consideration their experience and confidence with each technique.

The general limits of the endoscopic technique are well known and described in literature. Firstly, the endoscope provides a bidimensional image, which can reduce the perception of depth. In addition, other problems such as overlap of structures, shadowing, and parallax are associated with the bidimensional image. Secondly, the totally endoscopic techniques a one-handed surgical technique. The need to use one hand to hold the endoscope limits the use of surgical instruments to the other hand. This point is a major change compared to the classic surgical technique of microscopic ear surgery. Third, bleeding can be limiting in EES. It may be difficult for the surgeon to achieve good control of bleeding with one hand, particularly in the first steps of the learning curve. As bleeding can severely reduce visibility during the endoscopic procedure, it needs to be properly managed. Finally, a number of concerns have been reported regarding thermal tissue damage of the inner or middle ear during the use of the endoscope [17].

Thus, from the aforementioned discussion one can infer that that the endoscopic approach can be easily combined with the microscopic approach and has proven beneficial. The use of ear endoscopy as an ancillary method during surgery improved the assessment of the cavity after the complete removal of the cholesteatoma with the aid of a microscope. This further increases the surgeon's confidence in total cholesteatoma removal thereby significantly reducing cholesteatoma recidivism rates. By doing so, endoscopes reduce the need to re-explore the mastoid during second-look surgery, help preserve the canal wall, and can redefine post-cholesteatoma follow-up protocols by channelling more patients away from a planned second look.

Conclusion

In our study endoscopic evaluation of middle ear and mastoid cavity after microscope assisted mastoidectomy revealed cholesteatoma in 15(33%) patients. It can be concluded that endoscopic assistance is a valid adjunct to classical microscopic approaches. Endoscope thus have a definite role in evaluation and management of cholesteatoma in middle ear, as it is able to detect remnant disease within the hidden area of middle ear cleft and thereby aids in its complete surgical clearance and thereby circumventing the need for second look procedures. Therefore, it can be inferred that endoscopy should be incorporated in the daily practice of otological surgical procedures.

Limitations

Although an attempt of post operative follow up was made, a majority of the patients were lost to follow up, so the post operative outcomes could not be documented further; however, in patients who did follow up no residual or recurrence disease were observed.

Supplementary Information

Below is the link to the electronic supplementary material.

Author contribution

RM conceived of the presented idea. DSP wrote the manuscript. RM and VW helped supervise the project. RM, VW and IS proof read the manuscript. JK provided assistance in covering the radiological aspect..All authors discussed the results and contributed to the final manuscript.