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\begin{document}

\title{Managing cholesteatoma in labyrinth fistula}



\author[1]{Min Yi Natalie Aw}%
\author[2]{Jiun Fong Thong}%
\author[2]{Barrie  Tan}%
\author[2]{Vanessa Tan}%
\affil[1]{NUS Yong Loo Lin School of Medicine}%
\affil[2]{Singapore General Hospital}%


\vspace{-1em}



  
  \date{May 27, 2024}


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\begin{abstract}
Objectives: To evaluate the management of cholesteatomas with
labyrinthine fistulas (LF), as well as the clinical characteristics and
postoperative hearing outcomes in a tertiary general hospital from 2011
to 2018. Design: Retrospective observational cross-sectional study using
hospital electronic medical records. Setting: Mastoidectomies done for
clinically suspected cholesteatomas. Participants: All patients who
underwent primary middle ear mastoidectomy for cholesteatomas. Main
outcome measures: Demographic data: age, gender, race, presenting
complaints. Preoperative HRCT temporal bone and intraoperative findings.
Change in hearing levels preoperatively and postoperatively. Results: 14
of 90 ears (15\%) with middle ear cholesteatomas were complicated by LF.
HRCT observed 93\% sensitivity and 95\% specificity in the
identification of LFs. Intraoperative findings include stapes erosion in
79\% ears (p\textless{}0.001), malleus erosion in 79\% ears, incus
erosion in 93\% ears, dehiscence of tegmen tympani in 64\% of ears
(p=0.016) and tympanic facial canal dehiscence in 45\% of ears. Matrix
was removed completely in 85\% (n=12) and matrix was left behind in 13\%
(n=2). 21.5\% (n=3) had preoperative dead ears. Postoperative hearing
results had a mean follow-up time of 2.1 years (1.5, 0.14-4.84). Matrix
removal group (n=9) had hearing levels with 78\% no change, 11.1\%
improvement and 11.1\% decrease in hearing levels, while matrix
preservation group (n=2) had decreased hearing levels. Conclusions:
Preservation of hearing in labyrinthine fistulas is possible with
cautious matrix removal and immediate repair of the fistula. Longer
follow-up of hearing of LF with matrix preservation may show poorer
hearing outcomes.%
\end{abstract}%



\sloppy


\textbf{Key points:}

\begin{enumerate}
\tightlist
\item
  We report labyrinthine fistulas in 15\% of middle ear cholesteatomas
  that underwent mastoidectomies.
\item
  We observe that preoperative HCRT had 93\% sensitivity and 95\%
  specificity in the identification of LFs.
\item
  Intraoperative findings include erosion of 79\% stapes, 93\% incus,
  79\% malleus and dehiscence in 29\% tegmen tympani and 64\% tympanic
  facial canal.
\item
  Significantly higher incidence of stapes erosion and tegmen dehiscence
  observed in cholesteatomas with labyrinthine fistulas compared to
  without.
\item
  6 out of 8 patients with complete matrix removal and fistula repair
  did not have a change in hearing. Hence it is possible to preserve
  hearing with complete matrix removal.
\end{enumerate}

\textbf{INTRODUCTION}

Labyrinthine fistulas (LFs) are formed from the erosion of the bony
labyrinth and occur as a complication in 2.7-21\% (1, 2) of
cholesteatomas.

Early identification of LFs allows better surgical planning to reduce
potential vestibulocochlear sequelae. While intraoperative diagnosis of
LFs occurs with clear visualisation of semicircular canal (SCC) fistula,
high-resolution CT (HRCT) temporal bone scans are currently mainstay
investigation preoperatively, with sensitivity of 53.8-100\% (3, 4) and
specificity of 90-100\% (3, 5).

Surgical management of LFs varies. Matrix may be left over the fistula
and the mastoid cavity exteriorised to prevent complications such as
sensorineural hearing loss and vertigo. Alternatively, matrix may be
completely removed and the fistula repaired.

\emph{Objectives}

We report our local experience in the management of LFs in middle ear
cholesteatomas, over an 8-year period, at a major tertiary hospital. We
aim to discuss the clinical characteristics, management and hearing
outcomes.

\textbf{Ethical considerations}

Ethics approval was obtained from the Singhealth Centralized
Institutional Review Board before commencement of the study (2019/2791).

\textbf{METHODS}

\textbf{Reporting guideline: STROBE}

A retrospective review was done for mastoidectomies performed between
July 2011 and July 2018 by 2 senior surgeons were identified via the
electronic surgical logbook. Patients with primary cholesteatomas were
included, excluding congenital cholesteatomas and incomplete data. Data
extracted comprised preoperative demographics, high-resolution CT (HRCT)
0.5mm thickness temporal bone scan results, intraoperative findings and
hearing results.

Diagnostic accuracy and correlations of non-contrast HRCT scans with
intraoperative findings were analysed for 1) erosion of structures:
ossicular chain, tegmen tympani, tympanic facial canal and semicircular
canal, 2) location of squames and 3) ossicular chain encasement. The
technique of matrix preservation or removal was dependent on surgeon
choice and intraoperative findings, such as presence of intact
endosteum. Material to repair LFs was also noted. Average air conduction
(AC), bone conduction (BC) and air-bone gap (ABG) pure tone threshold
(PTA) were performed at 500Hz, 1kHz and 2kHz for all patients pre- and
post-operatively. A change of BC PTA of 10dB or more is considered
clinically significant.

Statistical analysis was conducted using chi square test using IBM SPSS
statistic package, version 25. Cholesteatomas were categorized into
``LF'' and ``No LF'' groups. Continuous variables such as age and
hearing levels were reported as mean (standard deviation, range).
Comparisons of categorical variables were performed using the Pearson
chi-squared test.

\textbf{RESULTS}

\emph{Participants}

A total of 90 ears underwent mastoidectomies for primary middle ear
cholesteatomas during the 8-year period. 5\% (5/90) had bilateral
cholesteatomas. 15\% (14/90) of ears in 13 patients were found to have
LFs intraoperatively, with an equal number of left and right sided LFs.
54\% (7/13) of patients were male and 69\% (9/13) were Chinese. Mean age
of diagnosis was 52 years (19.6, 8-6).

\emph{Descriptive data}

Presenting complaints of ears with LFs were 80\% (12/14) hearing loss,
79\% (11/14) otorrhea, 29\% (4/14) giddiness, 7\% (1/14) tinnitus, 7\%
(1/14) facial palsy and 7\% (1/14) otalgia. 65\% (9/14) ears had both
hearing loss and otalgia.

HRCT accurately identified 13 of the 14 LFs diagnosed intraoperatively,
with a false positive of 4 ears and false negative of 1 ear. This
reflected a sensitivity of 93\% (13/14) and specificity of 95\% (72/76)
in the identification of LFs through semicircular canal dehiscence. All
fistulas were located in lateral SCC and 7\% (1/14) in superior SCC.

In LF group, intraoperative dehiscence was observed -- 29\% (4/14) in
facial canal, 64\% (9/14) tegmen tympani. Ossicular erosion occurred in
79\% (11/14) stapes, 79\% (11/14) incus and 93\% (13/14) malleus.
Intraoperative squames were found, 93\% (13/14) attic, 93\% (13/14)
middle ear and 71\% (10/14) mastoid. Ossicular chain encasement occurred
in 71\% stapes (10/14), 93\% (13/14) incus and 79\% malleus (11/14).
Compared to non-LF group, LF group noted a significantly higher
incidence of stapes erosion (p\textless{}0.001), dehiscence in tegmen
tympani (p=0.016) and SCC (p\textless{}0.001) {[}Table 1{]}.

\emph{Outcome data}

All cholesteatomas with LFs underwent canal wall down mastoidectomy and
primary mastoid obliteration with local tissue flaps (middle temporal
artery or inferior musculoperiosteal flaps). Middle ear reconstruction
utilized cartilage placed onto remnant stapes suprastructure if present
or stapes footplate if absent stapes. Surgeon 1 employed complete matrix
removal in 86\% (12/14) of LFs, by leaving the matrix and cholesteatoma
over the SCC till the last stage of operation, before delicately
removing the matrix. This was followed by immediate bone-wax sealing of
fistula in 50\% (6/12) and temporalis fascia in 8\% (1/12). As the
endosteum was intact in the remaining 5 cases, these cases were not
sealed. Surgeon 2 performed matrix preservation in the remaining 14\%
(2/14) SCC fistulas. Revision mastoidectomies for recurrent
cholesteatoma were required in 14\% (2/14). These 2 cases had complete
matrix removal, whereby time to recurrence was 5 years and 6 years
respectively.

Postoperative hearing PTAs were taken at a mean of 2.1 years (1.5,
0.14-4.84). Mean preoperative and postoperative BC thresholds were
38.4dB and 45.3dB while AC thresholds were 73.6dB and 79.4dB
respectively. 21.5\% (3/14) ears had preoperative severe to profound
sensorineural hearing loss. The remaining 11 ears were evaluated on
their pre and postoperative hearing {[}Table 2{]}. Of the 11 ears, 9
ears had their matrix completely removed and LF repaired, and 2 ears had
matrix preservation with a modified radical mastoidectomy performed as
the fistula was large.

Matrix removal group had hearing levels with no change in 78\% (7/9),
improvement in 11.1\% (1/12) and decreased in 11.1\% (1/12). Mean
preoperative and postoperative BC thresholds were 33.1dB (17.8, 13-68)
and 38.8dB (19.3, 13-68) respectively. Postoperative hearing thresholds
done within 120 days showed worsening hearing in 22\% (2/9) ears, that
subsequently had hearing restoration achieved at the last follow-up of
3.2 years and 1.6 years respectively.

The 2 LFs with matrix preservation had decreased hearing levels, after a
follow-up time of 3.2 years and 2.7 years respectively. Increase in BC
thresholds preoperatively to postoperatively were 30dB to 65dB over 2.7
years for patient 1 and 40dB to 72dB over 3.2 years for the other.

\textbf{DISCUSSION}

\emph{Key results}

Our study reported LFs in 15\% (14/90) of middle ear cholesteatomas. The
evaluation of cholesteatomas pre-operatively with HRCT yielded a high
sensitivity (92.9\%) and specificity (94.7\%) for LFs. Significantly
higher incidence of tegmen tympani dehiscence, stapes erosion were seen
in ears with LF. Matrix management method in our centre is based on
surgeon preference, considering the approximate fistula size based on
preoperative imaging and initial hearing. The two LFs with matrix
preservation were done due to Surgeon 2's suspicion of larger fistulas
and both patients hearing thresholds. Significantly better postoperative
hearing outcomes was observed in complete matrix removal than matrix
preservation in our study.

\emph{Limitations}

Analysis was limited to a small sample size in this case series and
variability of timing to postoperative hearing outcomes could have
affected the conclusiveness of results. In addition, only 2 patients had
matrix preservation and more patients are needed to make a better
comparison. Surgeon's preference of matrix management was also subjected
to selection bias.

\emph{Interpretation}

Labyrinthine fistula (LF) is a known complication of cholesteatomas,
most common in the lateral SCC, but also affects superior SCC in 6\% and
posterior SCC in 2\% of LFs (6). Clinical suspicion of LFs is limited by
non-specific symptoms -- mostly sensorineural or mixed hearing loss,
accompanied by vertigo, otorrhea and otalgia also present in chronic
otitis media. Classic clinical signs such as fistula sign may only have
a sensitivity of 21.7\% to 60\% (7), false negative rate of up to 54\%
(8). Also, there is lack of uniformity in performing the test.

While some centres have used the Dornhoffer and Milewski classification
to stage fistulas based on bony defects and size of fistulas to
determine surgical method, the fistula size, size and grade have been
reported to not correlate with surgical outcomes (9). Surgeon 1's
technique of matrix removal was applied to all LFs, irrespective of size
of fistula. Sealing of fistulas included bone wax and temporalis fascia,
consistent with literature also reporting the use of bone wax,
temporalis fascia, bone dust, tissucol, fibrin glue, Spongiostan and
autogenous tissues (6, 9).

Postoperative hearing deterioration rate has been reported in 2.8-26.9\%
(9), possibly attributed to the removal of cholesteatomas and
granulation tissue previously acting as conduits in conducting sound
into ear. Postoperative deterioration in sensorineural hearing loss
occurs in 23\% to 50\% that underwent complete matrix removal and 1 to
44\% for matrix left in-situ (9). Unlike the review by Lim et al (9),
our patients with matrix preservation had poorer hearing outcome,
perhaps due to longer follow-up time. Matrix removal, however, had
hearing preservation in 78\% although 2 ears had initial worsening
within 120 days postoperatively. This is in contrary to greater
deterioration of long-term hearing outcomes found by Katsura et al (10),
despite initial improvements within the first year, postulated to the
involvement of third window during the initial recovery stage.
Postoperative persistent hearing loss could be a result of inflammatory
effects of the remnant cholesteatoma matrix.

\emph{Generalisability}

We present our experience in matrix management in LFs, based on surgical
preference and labyrinthine manipulation, with findings consistent with
literature. Long-term hearing results for fistulas with matrix
preservation compared with removal could be explored further in future
studies.

(1493 words)

References

1. Rosito LPS, Canali I, Teixeira A, Silva MN, Selaimen F, Costa SSD.
Cholesteatoma labyrinthine fistula: prevalence and impact. Braz J
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2. Manolidis S. Complications associated with labyrinthine fistula in
surgery for chronic otitis media. Otolaryngol Head Neck Surg.
2000;123(6):733-7.

3. Karki S, Pokharel M, Suwal S, Poudel R. Correlation between
Preoperative High Resolution Computed Tomography (CT) Findings with
Surgical Findings in Chronic Otitis Media (COM) Squamosal Type.
Kathmandu Univ Med J (KUMJ). 2017;15(57):84-7.

4. Gomaa MA, Abdel Karim AR, Abdel Ghany HS, Elhiny AA, Sadek AA.
Evaluation of temporal bone cholesteatoma and the correlation between
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Insights Ear Nose Throat. 2013;6:21-8.

5. Vrabec JT. Imaging of labyrinthine fistula after repair with bone
pate. Laryngoscope. 2018;128(7):1643-8.

6. Quaranta N, Liuzzi C, Zizzi S, Dicorato A, Quaranta A. Surgical
treatment of labyrinthine fistula in cholesteatoma surgery. Otolaryngol
Head Neck Surg. 2009;140(3):406-11.

7. Jia M, Qin Z. {[}Diagnosis and surgical management of labyrinthine
fistula caused by cholesteatoma{]}. Lin Chuang Er Bi Yan Hou Ke Za Zhi.
2005;19(13):592-3.

8. Gormley PK. Surgical management of labyrinthine fistula with
cholesteatoma. J Laryngol Otol. 1986;100(10):1115-23.

9. Lim J, Gangal A, Gluth MB. Surgery for Cholesteatomatous Labyrinthine
Fistula. Ann Otol Rhinol Laryngol. 2017;126(3):205-15.

10. Katsura H, Mishiro Y, Adachi O, Ogino K, Daimon T, Sakagami M.
Long-term deterioration of bone-conduction hearing level in patients
with labyrinthine fistula. Auris Nasus Larynx. 2014;41(1):6-9.

\textbf{Hosted file}

\verb`LF Hearing Outcomes_Table1.docx`  available at \url{https://authorea.com/users/735657/articles/711854-managing-cholesteatoma-in-labyrinth-fistula}

\textbf{Hosted file}

\verb`LF Hearing Outcomes_Table2.docx`  available at \url{https://authorea.com/users/735657/articles/711854-managing-cholesteatoma-in-labyrinth-fistula}

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