Intraoperative Classification of Cholesteatoma Using ChOLE Classification and Evaluating its Treatment Outcomes Using Inside Out Approach Mastoidectomy

Abstract

The primary objective is to classify acquired cholesteatoma according to the ChOLE classification system based on the preoperative and intraoperative findings, and to describe prevalence of each stage. The secondary objective is to correlate the extent of inside out approach mastoidectomy required with the staged extent of cholesteatoma. A non-randomized Prospective Observational study conducted in 67 patients in a tertiary care hospital. Each case was categorized according to the ChOLE classification system including cholesteatoma extension, ossicular chain status, life threatening complications and eustachian tube dysfunction. Based on the extent of disease, inside out approach mastoidectomy was done and results analysed. Most patients presented with stage 2 disease [67%]. Canal wall was preserved for all stage I, and in stage II cholesteatoma canal wall was either kept intact, reconstructed or lowered based on the extent of erosion of posterior meatal wall and cholesteatoma extension. All stage III underwent canal wall down mastoidectomy. Staging of cholesteatoma by ChOLE classification allows standardization in reporting gravity of disease and surgical outcomes. Inside out approach mastoidectomy contributes to the successful surgical management of cholesteatoma by eradicating the disease with the creation of a smaller cavity.

Introduction

Abramson et al. defined Cholesteatoma as ‘a three-dimensional epidermal and connective tissue sac, conforming to the architecture of the middle ear, attic and mastoid with a capacity for progressive and independent growth at the expense of the underlying bone and tendency to recur after removal [1]. Cholesteatoma can be classified into two different types: congenital and acquired. It can also be classified based on growth patterns into posterior epitympanic, posterior mesotympanic, and anterior epitympanic cholesteatoma [2]. The prevalence of cholesteatoma in patients with chronic otitis media is 24.5% and it is more common in adults than in children [3]. Due to its aggressive growth and invasive nature, cholesteatoma has a tendency to cause extracranial and potentially fatal intracranial complications [4]. Otoscopic, otomicroscopic or otoendoscopic examination, audiometric assessment and radiological investigations are mandatory for an accurate diagnosis and further planning of treatment [5]. One of the most recent cholesteatoma classiifcation is ChOLE classification.

Currently surgery is the definitive line of management with an aim to create a safe and dry ear by exteriorizing the disease and improving hearing [6]. The choice for canal wall up versus canal wall down mastoidectomy has been extensively debated. Canal wall down techniques provide excellent exposure, complete removal of the disease, but are associated with cavity problems and require regular lifetime follow-up [7, 8].

The principle of inside out mastoidectomy is to follow the direction of spread along the natural pathways and avoid unnecessary drilling of sclerotic bone. Drilling from the attic to aditus, and through antrum and mastoid air cell system, is stopped just beyond the end of the sac and is followed by complete removal of the sac. When disease is not progressed beyond antrum (limited diseases), the necessity of the canal wall down technique is eliminated. Thus, inside out technique avoids unnecessary drilling of sclerotic bone and creating the cavities [9, 10]. Canal wall down mastoidectomy is done for disease extending beyond antrum, unresectable disease, labyrinthine fistula and unreconstructable posterior canal wall [11]. A canal wall down mastoidectomy can be technically made canal wall up by reconstructing scutum and posterior canal wall in limited disease [12].

To provide a basis for meaningful exchange of information among those treating chronic otitis media with cholesteatoma, a classification or staging system is necessary. It will allow standardization in assessment of gravity of the disease and in reporting of surgical outcomes based on the respective stages of cholesteatoma. Many attempts have been made to classify cholesteatoma, most commonly used staging systems are European academy of neurotology and Japanese otological society(EAONO/JOS)classification and recent ChOLE classification. Linder et al. first described ChOLE classification in the International cholesteatoma conference in Edinburgh in 2016. The ‘ChOLE’ classification is an acronym and it stages the disease based on Ch-cholesteatoma extention, O-ossicular chain status, L-life threatening complications and E-Eustachian tube function [13].

Objective

To classify acquired cases of chronic otitis media with cholesteatoma according to the ChOLE classification based on preoperative and intraoperative findings and to describe the prevalence of each stage.

The secondary objective is to correlate the extent of inside out approach mastoidectomy required with the staged extent of cholesteatoma.

Materials and Methods

A non-randomized Prospective Observational study conducted in 67 patients from Jan 2019 to August 2019.

• Inclusion criteria: All acquired cases of chronic otitis media with Cholesteatoma at the initial presentation.

• Exclusion criteria: Congenital cholesteatoma, Recurrent disease, Revision surgery and Previous history of any ear surgery except myringotomy for grommet insertion.

A detailed history taking and thorough otologic examination including a complete ENT examination, Otoendoscopy/Examination under microscopy was done. Pre-operative Pure tone audiometry, Xray Mastoid Schuller’s view, Routine blood investigations done. HRCT temporal bone performed when complications were suspected. All patients underwent postoperative pure tone audiometry (3 months). Patients were explained about the procedure and informed written consent was taken.

Each case was categorized according to the ChOLE classification system into different classes based on peoperative and intratraoperative findings and further staged [13].

1. Ch—Cholesteatoma extension: Class 1 is subdivided into 1a and 1b. The 1b include extension into sinus tympani. A limited extension into the protympanum (toward the bony isthmus of the Eustachian tube) from a predominant middle ear location is considered Ch1. Class 2 involve the middle ear, with further extensions into the attic and antrum (2a) up to the level of the lateral canal within the mastoid. The 2b involve anterior extension into the anterior epitympanum (supratubal recess) with optional further extension into the protympanum and/or extension into the sinus tympani. Class 3 encompasses extensive bone erosion, either of the external ear canal and/or the tegmen tympani. Class 4 incoperates 4a which is tympanomastoid cholesteatoma with infralabyrinthine, supralabyrinthine, or transcochlear extensions and 4b is apical petrous bone cholesteatoma.

2. O—Ossicular status at the end of surgery: Class 0-An intact and mobile ossicular chain. Class 1 reflects erosion of the long process of the incus with or without malleus head removal. Class 2 involves removal or erosion of the incus and stapes suprastructure with preservation of a mobile footplate and malleus handle. Classes 3a and 3b refer to a mobile stapes or mobile footplate without superstructure, and classes 4a and 4b are a fixed stapes or fixed footplate, respectively. The ‘‘O’’ classification is consistent with the Austin Kartush and Fisch classifications, which are already widely used.

3. L—Life threatening complications: L2—Mastoiditis, Mastoid fistula, Bezold’s or Luc’s abscess, Facial palsy, Labyrinthine fistula, Labyrinthitis or Tegmen defect requiring surgical repair. L4—Meningitis, Brain abscess, Seizures or Sigmoid sinus thrombosis.

4. E—Eustachian tube ventilation and mastoid pneumatisation: Degree of pneumatization of the mastoid is considered an indirect sign of Eustachian tube function. E0— > 50% of cells aerated, E1— < 50% aerated, E2—Poor pneumatisation and ventilation.

Stage: Stage I is defined as 1–3 points, Stage II as 4–8 points, and Stage III as all values above 8.

Surgical Procedure

Surgery was performed by a single surgeon who is trained in inside out approach mastoidectomy and is practicing the technique for more than 20 years. Most patients underwent mastoid exploration under local anesthesia except pediatric cases and in cases were general anesthesia was indicated. Post aural incision is made, subcutaneous tissue dissected. Temporalis fascia graft identified and harvested. The canal entered by making an incision along the posterior canal wall skin and a tympanomeatal flap elevated and middle ear visualized.

Inside-Out Approach

Canaloplasty: Widening of external auditory canal done by drilling. In this procedure, the bony meatus is widened using a 3 mm diamond burr by removing bone from the spine of henle and posterior and superior walls of the external auditory canal, taking away the bony overhang.

Atticotomy: It is unroofing of attic spaces by removing the outer attic wall. It is performed by curetting or drilling the scutum using 1–2 mm diamond burr, thus unroofing the attic space from within outwards. Ossicular status was noted. While drilling or curreting, great care is taken not to make contact with an intact ossicular chain to prevent transmission of vibrations to ossicles. If the anterior extent of cholesteatoma is not visualized, attic wall is further drilled anteriorly to expose the anterior attic space and supratubal recess for complete removal.

Epitympanomastoidectomy: After atticotomy the epitympanic space is completely visualized. If the disease is extending towards the antrum posteriorly, then the bone of the posteriosuperior wall is further widened till complete sac is visualized. If extending beyond the atticoantral regionand in cases of unreconstructable posterior canal wall defect, a canal wall down mastoidectomy was planned for adequate exposure. This was done by lifting the epitympanic portion of the cholesteatoma to visualize the level of facial canal and the stapes. Once the position was known, the posterior canal wall was lowered adequately until the posterior extent is seen completely. Facial ridge was lowered adequately till the level of the lateral semicircular canal.

Disease clearance, reconstruction and closure: The entire cholesteatoma matrix carefully removed. All cases were given a functioning ear by performing tympanoplasty. Temporalis graft used for tympanic membrane reconstruction. In all canal wall down surgeries, meatoplasty was performed to promote self-cleasing of the cavity and facilitate adequate postoperative care. After placing the graft, the EAC packed with gelfoam and medicated merocel ear wick was placed. Subcutaneous sutures with vicryl done.

Postoperative Care

Mastoid compression bandage applied. Patient discharged on post-operative day 2. Mastoid dressing removed on first review after 1 week. Oral antibiotics continued for 10 days. The first cavity cleaning was done at 2nd week postoperative visit and merocel ear wick removed at this time.

Postoperative Evaluation

Patients were followed up weekly for the first month, then once a month for 3 months and then once in a month for a duration of 9 months. Cases were evaluated for healing of the cavity, wax or collection of debris or any other post-operative complaints. Pure tone audiometry was done after 3 months. Pre- and post-operative air–bone–gaps were compared to analyze hearing outcomes.

Statistical Analysis

Due to non-normal distribution, analysis done using the Wilcoxon sign rank test using Microsoft excel 2010 to analyze pre and post-operative pure tone audiometry results and air–bone gap values.

Results

There were 67 patients in our study. Patient’s age was varying between 13 years and 70 years with the mean age of 32.74 years. We had 46.3% (31) males and 53.7% (36) females and thereby found a female preponderance although literature gives evidence of increased male prevalence. 36 patients had right, 27 patients had left ear and 4 presented with bilateral disease.

According to ChOLE classification, Stage 1 had 14 [21%], Stage 2 had 45 [67%] and Stage 3 had 8 [12%] patients.

The extension of the Cholesteatoma in the study population as shown in Fig. 1. Ch 1a i.e. Middle ear space involvement without extension to sinus tympani was observed in 8 [12%]. Middle ear with sinus tympani involvement (Ch1b) was seen in 4 patients [6%]. Class 2 and 3 extensions of cholesteatoma were Ch2a—12 [18%], Ch2b—9 [13.5%], Ch3—32 [47.5%]. Class 4 had the lowest incidence Ch4a—2 [3%], petrous apex involvement (Ch 4b) was not seen in our study.

Fig. 1.

Cholesteatoma extension

Ossicular chain status at end of surgery in the study population as shown in Fig. 2. Nine [13.43%] patients had intact ossicular chain. O1 i.e.; Malleus and Stapes present with eroded Incus 19 [28.35%], was the most frequently observed. Other classes were O2—13 [19.4%], O3a—14 [20.89%], O3b—11 [16.41%], O4a—1 [1.5%]. Immobile stapes footplate (O4b) was not seen in our study.

Fig. 2.

Ossicular status

Life threatening complications in our study include L2—6(8.95%) patients in the form of 2 Bezold’s abscess cases, 1 Facial nerve palsy, 2 Labyrinthine fistulas and 1 patient with Tegmen defect with required surgical repair. L4 seen in 1 patient in the form of brain abscess. Dehiscence of the horizontal segment of facial nerve canal was seen in 12 cases but was associated with facial palsy only in one patient.

Most patients in our study had a poor Eustachian tube function. E2—63%. 9% patients were in E0 and 28% patients in E1.

Operative Details

89.5% (60) patients underwent surgery under local anesthesia while 10.5% (7) in general anesthesia. For all 67 patients, temporalis fascia graft harvested via post-aural incision. Mastoid cortex drilled by inside-out technique in all 67 (100%) patients. The posterior canal wall was intact, lowered and reconstructed in 26 (38.8%), 28 (41.8%) and 13 (19.4%) patients respectively.

Ossicular reconstruction was done in 32 (47.8%) patients. Reconstruction material used was Autologous incus, cartilage and PORP in 25, 4 and 3 patients respectively. Ossicular reconstruction was not done in 35 (52.2%) patients either due to an intact ossicular chain or in cases of type III tympanoplasty where graft was placed directly over the stapes suprastructure in view of destroyed malleus and incus (Table 1). Meatoplasty was performed in all cases of canal wall down mastoidectomies. We achieved total disease clearance in all patients.

Table 1.

Material for ossicular reconstruction

Material	Number	Percentage
Autologous incus	25	78.2
Cartilage	4	12.5
PORP	3	9.3

In all cases of stage I of ChOLE classification accounting 14 [20.9%] patients, the canal was left intact. In stage II, the decision to keep the canal wall intact or reconstruct or lower was based on the extent of cholesteatoma and erosion of posterosuperior bony meatal wall. If the posterosuperior wall was eroded more than 1/3rd, then the facial ridge was lowered as it is difficult to clear the disease and reconstruct. All stage III patients underwent canal wall down mastoidectomy (Table 2).

Table 2.

Correlation of ChOLE classification staging with the extent of inside out approach

Posterior canal wall	Stage of cholesteatoma
	Stage 1	Stage 2	Stage 3
Intact	14	13	0
Reconstructed	0	13	0
Lowered	0	19	9

Based on the cholesteatoma extension, the canal was left intact for all class 1 [17.9%] patients. For class 2 patients canal wall was left intact or reconstructed depending on antral extension. In class 3, the canal wall was either reconstructed or lowered based on the spread of disease and extent of erosion of the posterior meatal wall. All class 4 underwent canal wall down mastoidectomy (Table 3).

Table 3.

Correlation of Cholesteatoma extension with the extent of inside out approach

Posterior canal wall	Extension of cholesteatoma
	1a	1b	2a	2b	3	4a	4b
Canal wall intact	8	4	8	6	0	0	0
Reconstructed	0	0	4	3	6	0	0
Lowered	0	0	0	0	26	2	0

Post-operative Evaluation

Patients were followed up weekly for the first month, then once in 2 weeks for 3 months and then once in 6 months. At 3 months post-op, cavity was healed in 56 (81.7%) and discharging cavity was noted in 11(18.3%) patients incidence of post-operative superficial infection and granulation tissue were 9% and 7.4% respectively (Table 4). Pure tone audiometry was done 3 months post operatively (Table 5).

Table 4.

Post-operative status after 6 months

	Number	Percentage
Healed cavity	56	81.7
Discharging cavity	11	18.3
Superficial infection	6	9
Granulations	5	7.4
Meatal stenosis	1	1.5
Recidivism	0	0

Table 5.

Pre and post-op air conduction and air–bone gap

PTA	Visit	Mean	SD	p value
Air conduction	Preoperative	45.52	18.5	p = > 0.01
	Follow up	36.72	17.63
Air–bone–gap	Preoperative	32.52	17.52
	Follow up	24.62	16.58

Discussion

In order to provide a basis for meaningful exchange of information among those treating cholesteatoma, the ChOLE classification and staging system can be used in clinical practice. It is relatively new for staging of cholesteatoma and not many studies have been done on the prevalence of each stage and its application in clinical practice.

Inside-out transcanal microscopic approach was done for all patients. This technique includes canaloplasty, atticotomy, epitympanomastoidectomy where posteriorosuperior canal wall is either reconstructed or lowered through inside out approach according to the magnitude and location. In our study most cases (67%) were in stage II disease. In 12 cases the cholesteatoma extension was confined to middle ear space and sinus tympani (Class 1) and in 55 cases disease progressed towards anterior epitympanic recess, antrum, aditus and further beyond. In 28 patients the canal wall was lowered due to the extensive disease and difficulty in reconstruction. The advantage of inside out approach mastoidectomy was even though the canal wall was lowered, the size of the cavity was significantly smaller. In 39 patients the posterior meatal wall was either left intact or reconstructed. Attic and posterior wall reconstruction was done using tragal cartilage in our study. For ossicular reconstruction, refashioned incus was frequently used. Other materials used were septal cartilage and PORP. In all the cases disease was completely cleared and reconstructed in the same setting.

According to Linder et al. the involvement of the supratubal recess and protympanum represent difficult area to reach while preserving the malleus head or chorda but with current techniques proper removal of disease from these areas is possible and it does not upgrade the staging of ChOLE classification system. However, cholestatomas extending beyond the lateral semicircular canal into the mastoid and may reach the sigmoid sinus.

In our study all stage I patients underwent atticotomy with intact canal wall. In Stage II, the decision to keep canal wall intact/reconstruct or lower was based on intraoperative assessment of cholesteatoma spread and extent of erosion of posterior meatal wall. All stage III underwent canal wall down mastoidectomy.

Linder et al. described based on cholesteatoma extent that class 1 cholesteatoma can be easily removed via transcanal route. Class 2 extension has a difficult angle to access but removal is facilitated by current techniques. Class 3 expands beyond lateral semicircular canal and requires a route of access to mastoids in the form of inside out mastoidectomy with or without canal reconstruction [13]. This is consistent with intraoperative findings in our study but most of our patients underwent canal wall down mastoidectomy via inside out approach for class 3 cholesteatoma for adequate exposure of cholesteatoma sac to prevent residual disease. There were no cases of post-operative residual disease or recurrence.

Post-operative mean air bone gap was 24.62 decibels. The mean difference in AB gap was 3.94 decibels. This is similar to study done by Chamoli et al. and Kuo et al. which showed a mean difference in AB gap of 3.57 and 5.7 db respectively [6, 14]. Thus, we had a statistically significant improvement in hearing (p = > 0.01).

Conclusion

In our study according to ChOLE classification stage II cholesteatoma was the most prevalent (67%). Stage III was least common in our study group. Canal wall was preserved for all stage I patients. In stage II, the canal wall was either kept intact, reconstructed or lowered based on the extent of erosion of the posterior meatal wall and extension of cholesteatoma. All stage III underwent canal wall down mastoidectomy. Staging of cholesteatoma by ChOLE classification allows standardization in assessment of gravity of disease and in reporting surgical outcomes. In our study, inside out mastoidectomy contributes to the successful surgical management of cholesteatoma by eradicating the disease with the creation of a smaller cavity, by avoiding unnecessary drilling of bone beyond the extent of cholesteatoma.

Compliance with Ethical Standards

Conflict of interest

None declared.

Ethics Approval

Approved by institutional ethical committee.

Informed Consent

Informed consent obtained from all patients participating in the study as waved by the institutional ethical committee.