Lasers in Cholesteatoma Surgery: A Systematic Review

Abstract

Objectives:

The mainstay of cholesteatoma treatment is surgical and requires the removal of all squamous epithelium from the underlying normal structure. The application of laser technology in middle ear and mastoid surgery has shown promise in achieving both disease eradication and hearing preservation. This systematic review aims to include studies that have assessed the application of laser to the treatment of cholesteatoma and to review its outcomes in terms of disease eradication as well as hearing results.

Method:

Two independent researchers conducted a systematic review of the literature on MEDLINE and Cochrane library, according to PRISMA guidance.

Result:

The search resulted in 12 papers, reporting on 536 participants that fulfilled the inclusion criteria. The hearing results did not show that using laser surgery improved hearing in cholesteatoma surgery, but neither has the use of laser shown to deteriorate hearing. With regards to the prevention of residual/recurrent cholesteatoma, the current literature reports a residual/recurrent rate of 0% to 33%. The complication rate of facial palsy is 0.6%.

Conclusion:

While there is certainly a role for future studies especially randomised large-cohort prospective comparative studies, the current literature suggests that laser may have a role in prevention or minimizing of residual cholesteatoma and generally have a safe hearing outcome profile.

Introduction

Cholesteatoma is a collection of squamous epithelium with potential to cause progressive erosion and destruction of important structures within the temporal bone. The mainstay of treatment for this disease is surgical and requires the removal of all squamous epithelium from the underlying normal structure. While the prime objective of mastoid surgery for cholesteatoma is complete disease removal, creating a safe, dry, and disease-free ear, ¹ preservation of hearing is also one of the important objectives. Traditionally, mastoidectomy techniques can be classified into 2 main categories: canal wall down and canal wall up. In recent times, a variety of surgical modifications have been developed and techniques such as transcanal endoscopic ear surgery ^2,3 and laser-assisted cholesteatoma surgery have been applied.

The application of laser technology in middle ear and mastoid surgery has shown promise in achieving both disease eradication and hearing preservation. This systematic review aims to include studies that have assessed the application of laser to the treatment of cholesteatoma and to review its outcomes in terms of disease eradication as well as hearing results.

Methods

The systematic review was undertaken in accordance with the general principles recommended in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). ⁴ A systematic computer-based literature search was performed on the biomedical bibliographic databases: MEDLINE and Cochrane library. The search was performed by 2 independent researchers and included the search terms: “(cholesteatoma) AND (laser)” with the filters: “Text availability: Full Text,” “Species: Humans,” and “Language: English.”

Inclusion and Exclusion Criteria

The inclusion and exclusion criteria for the population of interest, outcomes, and study design are presented in Table 1.

Table 1.

Inclusion and Exclusion Criteria.

	Inclusion criteria	Exclusion criteria
Population	Cohort studies Case reports Paediatric and adult	In-vitro studies
Outcomes	Hearing outcomes Presence or absence of disease on follow-up	None
Study design	Prospective or retrospective cohort, case–control, and cross-sectional. Case reports. Full-text was available Published in English language	Book chapters, reviews, editorials and commentaries, interventional studies

Data Analysis

Two authors (K.L. and M.S.) independently selected studies, extracted data, and assessed the quality of included studies. Data were extracted from each study and included information on the article identification, year of publication, population (continent), evaluation period (for longitudinal studies), number of patients, hearing assessment methods, residual or recurrent cholesteatoma outcomes, and mean age of subjects.

Results

The electronic searches identified 44 citations. Of these, 28 were excluded after reviewing their title and abstract. Of the remaining 16 citations obtained as full-text, 4 were excluded as they were review papers. ^{1,5 -7} Twelve studies, reporting on 536 participants, fulfilled the inclusion criteria and were included in the systematic review. A PRISMA flowchart of the study selection process is shown in Figure 1.

Figure 1.

Flowchart of the study selection process.

The characteristics of the included studies are shown in Table 2. These studies were published between 1997 and 2020 and conducted in America, Asia, and Europe. Four of them were case reports, ^{8 -11} 5 were retrospective cohort studies, ^{12 -16} and 3 were prospective cohort studies. ^{17 -19} Recruited participant numbers ranged from 2 ^8,11 to 200. ¹⁶

Table 2.

Characteristics of Included Studies.

Reference	Design	Population	Number of patients	Type of laser used	Laser setting	Type of surgery (primary or revision)	Mean age in years (range)
Nagel 1997 12	Retrospective cohort study	Europe	18	Er: YAG	0.2 mm spot size, pulse mode 0.25 milliseconds, rate of 2 Hz, total energy 225-25 000 mJ	Primary	Not reported (7-64)
Nishizaki et al, 2001 8	Case report	Asia	2	KTP	0.4 mm spot size, 4-5 W for 0.2 seconds in pulse mode	Primary	31.5 (21-42)
Hamilton, 2005 17	Prospective cohort study	Europe	36	KTP	Not reported	Primary	Not reported (6.6-75.3)
Hamilton, 2010 18	Prospective cohort study	Europe	149	KTP	Not reported	Primary	34 (4-82)
Eskander et al, 2010 9	Case report	America	3	KTP	300-800 mW in a single or repeated pulse mode with duration of 4 seconds at 0.05 seconds intervals	Revision	11.7 (8-14)
Yau et al, 2015 13	Retrospective cohort study	America	7	Argon	1 W and pulsed duration of 100 milliseconds on and 100 milliseconds off	1 Revision 6 Primary	24 (6-48)
Lee et al, 2015 14	Retrospective cohort study	Asia	10	CO2	3 W continuous mode	Primary	3.5 (1-5.5)
Landegger and Cohen, 2016 10	Case report	America	3	CO2	2-4 W, single pulse, 100 millisecond	1 Revision 2 Primary	7.4 (6-11)
Stevens et al, 2018 11	Case report	America	2	CO2	200-micron spot size, 2-4 W on continuous pulse mode	Primary	25 (16-35)
Basu and Hamilton, 2019 15	Retrospective cohort study	Europe	36	KTP	Not reported	Primary	Not reported (14-82)
Lee et al, 2019 16	Retrospective cohort study	Asia	200	CO2	1 W in continuous mode	Primary	35 (15-82)
Sharma et al, 2020 19	Prospective cohort study	America	70	KTP	0.3 W (eg, on the stapes superstructure) and 1 W (eg, with a defocused beam to ablate potentially unseen remnants)	Primary	10.5 (1.8-18)

Application of Laser and Reported Complications

Table 3 summarizes the different ways laser was applied in surgery in all groups.

Table 3.

Summary of Application of Laser.

Application of laser	References	Complications reported
Remove cholesteatoma matrix from ossicles, for preparing ossicles for middle ear reconstruction	Nagel, 1997 12 ; Hamilton, 2010 18 ; Lee et al, 2019 16	None reported
Remove disease adherent to ossicles and from regions adjacent to the ossicles. Laser also used to heat the surface of all bone and soft tissue, apart from the area over the facial nerve	Hamilton, 2005 17 ; Eskander et al, 2010 9 ; Sharma et al, 2020 19	Eskander et al, 2010 9 : 3 delayed facial nerve palsies (onset 7-9 days postoperative). The bony covering of the facial nerve was not dehiscent or breached in any of the cases, and at no time did the intraoperative facial nerve monitor indicate irritative activity. All patients had recovered facial nerve function to baseline by postoperative day 52.
Without damaging the ossicular ligaments, the incus alone or the incus and malleus were amputated to maintain the ossicular chain to allow for resection of cholesteatoma	Nishizaki et al, 2001 8	None reported
Laser as an adjunct to endoscopic ear surgery	Yau et al, 2015 13 , Landegger et al, 2016 10	None reported
Transcanal laser-enabled ablation and resection for intratympanic membrane congenital cholesteatoma	Lee et al, 2015 14	None reported
Laser used to ablate persistent stapedial artery	Stevens et al, 2018 11	None reported
Laser used on cholesteatoma over a cochlear or vestibular fistula	Basu and Hamilton, 2019 15	Two fistulas were inadvertently perforated, each was closed by a fat graft and then covered by fascia

Hearing Results

Hearing results were not reported in 4 papers. ^9,10,13,19 Hearing thresholds were reported using either pure tone audiogram results, bone conduction thresholds only, or distorted product otoacoustic emission (for children). Because of the heterogeneous way of reporting hearing outcomes, it was not possible to compare hearing outcomes in different groups. Table 4 shows a summary of hearing outcomes and in general, any worsening of hearing was limited to a range of deterioration between 0.3 to 15 dB.

Table 4.

Hearing Outcomes.

Hearing threshold measurement	Studies	Outcome
No hearing results	Eskander et al, 2010 9 , Yau et al, 2015 13 , Landegger and Cohen, 2016 10 , Sharma et al, 2020 19	No results reported
No specifics on how hearing was tested	Hamilton, 2005 17	No change in hearing
Bone conductions (BC) outcome	Nagel, 1997 12	6 cases: showed a lowered BC threshold of 5-10 dB at 4 kHz. 11 cases: BC threshold at 4 kHz improved by 5-10 dB. 1 case: BC at 4 kHz fell significantly by 15 dB.
	Basu and Hamilton, 2019 15	The average change in bone conduction threshold was −0.3 dB deterioration in hearing.
Pure tone audiogram (PTA) results	Nishizaki et al, 2001 8	No change in BC. Closure of air–bone gap.
	Hamilton, 2010 18	Postoperative cochlear function between ossicular chain intact and disrupted groups were not significant (intact: +1.5 dB HL, disrupted: −0.6 dB HL)
	Stevens et al, 2018 11	Hearing results in one case showed some improvement
Distorted product otoacoustic emission (DPOE)	Lee et al, 2015 14	No change in hearing
	Lee et al, 2019 16	Hearing levels worsened after the operation in 15.5% of patients, but 97% of these children remained within 10 dB of their preoperative levels.

Abbreviation: BC, bone conductions.

Disease Eradication

As part of their outcome measure, 9 papers ^{10,11,13 -19} looked at the presence or absence of residual disease at either a second stage operation, with diffusion-weighted magnetic resonance imaging or computed tomography scan at least 12 months after the first operation or clinical observation. There were 2 papers that had a control group and compared the outcomes of laser versus no laser, while Hamilton in 2005 ¹⁷ showed that using a laser significantly reduced the chance of residual disease after 12 months, Sharma et al in 2020 ¹⁹ did not report any significant difference between using the laser or not. The other papers report their recurrence rate between 0% and 33%. ^{10,11,13 -16,18} Table 5 summarized the disease eradication outcomes.

Table 5.

Disease Eradication Outcomes.

Reference	Design	Length of follow-up (after first operation)	Method of detecting residual/recurrent disease	Number of patients	Presence of control group	Results
Hamilton, 2005 17	Prospective cohort study	At least 12 months	Second stage operation	36	Yes, n = 33 (no laser)	Non laser: 30% residual Laser group: 2.8% residual (P = .003).
Hamilton, 2010 18	Prospective cohort study	12 months	Second stage operation	149	No	Preservation of ossicular chain group: 11.2% residual Interrupted ossicular chain group: 11.6% residual (P = .88)
Yau et al, 2015 13	Retrospective cohort study	Mean follow-up 19 months (range: 5-38)	MRI diffusion-weighted	7	No	No recurrence
Lee et al, 2015 14	Retrospective cohort study	Not reported	Clinical examination	10	No	No recurrence
Landegger and Cohen, 2016 10	Case report	6-7 months	Second stage operation	3	No	33% recurrence
Stevens et al, 2018 11	Case report	8 months	Second stage operation	2	No	No recurrence, but one lost to follow-up
Basu and Hamilton, 2019 15	Retrospective cohort study	12 months	Second stage operation	36	No	No recurrence
Lee et al, 2019 16	Retrospective cohort study	8-12 months	CT imaging. Second-look operations were performed when CT suggestive of disease	200	No	7.5% had residual disease
Sharma et al, 2020 19	Prospective cohort study	More than 12 months follow-up	Second-stage surgery (n = 46), MRI diffusion-weighted (n = 4), (mean of 3.2 years postoperative), observation in clinic (n = 33; mean follow-up of 3.0 years).	60	Yes, n = 13 (no laser)	Laser group: 6% residual Non laser: 7.6% residual

Abbreviations: CT, computed tomography; MRI, magnetic resonance imaging.

Discussion

In the last 2 decades there have been a variety of publications looking at the outcomes of laser on cholesteatoma surgery. Majority of them have been nonrandomized retrospective cohort studies and case reports, with very few large longitudinal cohort studies with a control group.

While laser surgery is thought to facilitate atraumatic dissection of cholesteatoma from mobile ossicles and therefore reducing the risk of trauma to the cochlea from mechanical traction, there has only been one study ¹⁸ that compared the outcomes from 2 groups that were treated with laser (patients with ossicular chain intact vs disrupted). The hearing results did not show that using laser surgery improved hearing in cholesteatoma surgery, but neither has the use of laser shown to deteriorate hearing.

With regard to the prevention of residual/recurrent cholesteatoma, the current literature reports a residual/recurrent rate of 0% to 33% with 2 prospective papers comparing between a laser and nonlaser group. A single well-designed comparative study has shown sufficient benefit to lead to the claim that KTP laser use in cholesteatoma surgery has been shown to reduce the risk of residual cholesteatoma with a number needed to treat of 4 cases. ¹⁷ However, the follow-up duration of the studies mentioned in this review has not been sufficient to provide a dependable assessment regarding the longer-term effects of laser-assisted surgery on the recidivism of cholesteatoma, which is a time-dependent phenomenon. Continued long-term vigilance in this regard is therefore recommended.

Even though there were a variety of lasers being reportedly in use, there was no evidence portraying any laser as being ineffective at removing cholesteatoma. There have also been no studies directly comparing the different types of laser and any difference in clinical outcomes. Facial palsy is a potential complication of laser-assisted surgery and most papers recommend not applying laser to anywhere near or directly to the facial nerve. Combining all the cases together, the complication rate of facial palsy was 0.6%.

While there is certainly a role for future studies especially randomised large-cohort prospective comparative studies, the current literature suggests that laser may have a role in prevention or minimizing of residual cholesteatoma and generally have a safe hearing outcome profile.