CLINICAL FEATURES OF CHOLESTEATOMA WITH LABYRINTHINE FISTULAE

Masafumi Ohki, Shigeru Kikuchi, Atsushi Ohata, Takeshi Tsutsumi, Sunao Tanaka, Atsushi Tahara, Yuka Baba, Shinji Urata, Jyunichi Ishikawa

Department of Otolaryngology, Saitama Medical Center, Saitama, Japan

Introduction

Chronic otitis media with cholesteatoma can cause various complications such as vestibular dysfunction, sen-sorineural hearing loss, facial palsy, and meningitis. Inner-ear disturbance is usually induced by labyrinthine fistulae, e.g., semicircular canal fistula or cochlear fistula. In this study, we evaluated the clinical features of cholesteatoma with labyrinthine fistulae.

Material and methods

We enrolled 220 patients with cholesteatoma; of these patients, 210 had acquired cholesteatoma and ten had congenital cholesteatoma. All patients underwent tympanoplasty and/or mastoidectomy surgical procedures. Pure-tone audiometry was performed, and computed tomography (CT) scans (axial and coronal views) were examined. Labyrinthine fistula was detected by CT scan pre-operatively and confirmed by observation during surgery.

Results

Fistula location

Cholesteatoma with labyrinthine fistula was diagnosed in 19 patients, including 18 patients with acquired cholesteatoma and one with congenital cholesteatoma. The fistulae were located in the following regions in the 19 patients: 13 in the lateral semicircular canal and six in the cochlea. The site of the cochlear fistulae was the oval window. Patients with lateral semicircular canal fistulae showed defects of incus by 73% and patients with cochlear fistula showed defects of stapes by 83%. The pre-operative CT scan detected 82% of the lateral semicircular canal fistulae, while 83% of the cochlear fistulae (oval window) were not revealed. Because a differential diagnosis between bony and membranous fistula in the lateral semicircular canal could not be confirmed by CT scan, this was confirmed by observation during surgery.

Fistula type

Labyrinthine fistula is classified into two types: bone fistula, which affects only the bony labyrinth, and membranous fistula, which erodes both the bony and membranous labyrinths. Bony and membranous fistu-lae were found in 11 and eight patients, respectively. Membranous fistulae were found in two of 13 patients

with lateral semicircular canal fistulae, while the other 11 had bony fistulae. All six cochlear fistulae of the oval window were membranous fistulae. Labyrinthine fistulae often cause vertigo, dizziness, hearing loss, or tinnitus. Pre-operative vertigo was observed in two patients with membranous fistula of the lateral semicircular canal. Half of the patients with bony fistulae of the lateral semicircular canal experienced pre-operative vertigo, even though the perilymph did not leak out. Only 33% of patients with membranous fistulae of the cochlea complained of vertigo pre-operatively.

Hearing

The bone-conduction hearing thresholds did not deteriorate in the majority (89%) of patients who underwent surgical removal of the matrix covering the labyrinthine fistulae (Fig. 1). A patient with acute sensorineural hearing loss and vertigo secondary to labyrinthine fistula showed improvement in bone-conduction hearing thresholds after complete matrix resection and closure of the lateral semicircular canal fistula by surgery. Removal of the matrix covering the oval window did not affect bone-conductive hearing loss thresholds. However, one patient with a cochlear fistula who did not show sensorineural hearing loss in the first few months after surgery, became deaf six months after surgery.

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Fig. 1. Bone-conduction hearing thresholds before and after surgery. The bone-conduction hearing thresholds did not deteriorate in the majority of patients who underwent surgical removal of the matrix covering the labyrinthine fistulae.

Discussion

Although both acquired and congenital cholesteatoma can lead to several complications such as ossicular erosion, facial palsy, intracranial infection, and labyrinthine fistula, these complications tend to present less often in congenital cholesteatoma than in acquired cholesteatoma.1 The reported frequency of labyrinthine fistula is lower in congenital cholesteatoma (0–5%)14 than in acquired cholesteatoma (7–12.5%).58 We postulate that the risk of labyrinthine fistula is related to various factors such as duration, location, and infection. Firstly, long-term exposure to the cholesteatoma matrix increases the probability of labyrinth destruction. Secondly, cholesteatoma usually occurs near the lateral semicircular canal and oval window, especially in acquired cholesteatoma. Thirdly, infection accelerates the destructive feature of the cholesteatoma matrix. These factors determine the destructiveness of the cholesteatoma.

Management of labyrinthine fistulae with total or incomplete matrix removal to prevent deterioration of cochlear or vestibular function is controversial.9 Some surgeons recommend preservation of the matrix over the fistula with exteriorization through an open cavity, while others completely remove the matrix over the fistula to prevent further effects.9 Careless removal of the matrix over the fistulae may result in deterioration of the bone-conduction hearing level. However, careful removal of matrix over the fistula could prevent sensorineural hearing loss. Our study suggests that complete resection of the matrix covering the labyrinthine fistula preserves bone-conduction hearing levels and is a safe and effective management method. This safety is supported by the report that cochlear function was preserved after interruption of lateral semicircular ca-nals.10 Furthermore, it may improve acute sensorineural hearing loss secondary to cholesteatoma fistula.11 Improvement of sensorineural hearing loss after complete removal of the matrix over a lateral semicircular canal fistula was observed in one of our cases. Otherwise, preserving the cholesteatoma matrix over the fistula may induce delayed sensorineural hearing loss due to suppressive labyrinthitis by 10%.12 Total removal of the cholesteatoma matrix over the fistula is advantageous with respect to preventing both further possible osteoclastic bone resorption by the cholesteatoma matrix and possible erosion under the matrix.9 However, the risk of complications increases for large fistulae. A procedure to remove the matrix may destroy the membranous labyrinth because the adherent membranous labyrinth is pulled. In this case, a second-look operation or preservation of the cholesteatoma matrix over the fistula through an open cavity may be appro-priate.12 Until the secondary operation, the matrix might dissolve spontaneously and the size of fistula may diminish if infection is not present.13 In the absence of infection, the risk of adhesion of the matrix and the membranous labyrinth may decrease.

A CT scan may suggest the presence of lateral semicircular canal fistulae, but cochlear fistulae of the oval window are difficult to detect pre-operatively. Removal of the cholesteatoma is very risky in cases of covert labyrinthine fistulae. In cases with stapes defects, a cochlear fistula of the oval window should be considered.

References

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Address for correspondence: Masafumi Ohki, Department of Otolaryngology, Saitama Medical Center, 1981 Kamoda, Kawagoe-shi, Saitama 350–8550, Japan. m-ohki@umin.ac.jp

Cholesteatoma and Ear Surgery – An Update, pp. 403–405

Edited by Haruo Takahashi

2013 © Kugler Publications, Amsterdam, The Netherlands