SEMICIRCULAR CANAL FISTULA WITH MIDDLE-EAR CHOLESTEATOMA – REPORT OF 24 CASES
Introduction
Semicircular canal fistula occurs in approximately 5~10% of cases of middle-ear cholesteatoma and is reported to occur commonly in the lateral semicircular canal.
Our objective is to understand the incidence, location, pre- and post-operative symptoms, diagnosis and procedure in cases with semicircular canal fistula.
Materials and methods
Between January 2003 and December 2011, at the Department of Otolaryngology, Fukushima Medical University, 312 cases with middle-ear cholesteatoma underwent surgical treatment.
Pre-operative CT imaging was performed using MDCT (Aquilion®, TOSHIBA) and CBCT (3D-Accuitomo®, MORITA) systems. The depth of the labyrinthine fistula was classified using the Milewski & Dornhoffer classification (Table1).1
Table 1. Milewski & Dornhoffer classification
Type | |
I | erosion of the bony labyrinth with an intact endosteum. |
IIa | opened perilymphatic space with undisturbed perilymph |
IIb | opened perilymphatic space with disturbed perilymph. |
III | opened perilymphatic space with a disturbance of the underlying membranous labyrinth. |
Results
In 24 of the 312 cases, a semicircular canal fistula was confirmed during the operation. The incidence of semicircular canal fistula was 7.7% in all patients.
Vertigo was present in 79.2% of all patients, fistula symptom was positive in 50% of all patients pre-operatively.
Diagnosis of semicircular canal fistula was made before surgery for 91.7% of patients on the basis of symptoms, signs and CT imaging.
The fistula was located in the lateral semicircular canal in 22 cases (91.7%), located in the anterior semicircular canal in one case (4.2%), and located in the lateral and anterior semicircular canals in remaining one case (4.2%)(Table2).
Table 2. Location of the fistula (n = 24).
Location | n |
Lateral semicircular canal | 22 (91.7%) |
Anterior semicircular canal | 1 (4.2%) |
Lateral and anterior semicircular canals | 1 (4.2%) |
Table 3. Classification of the semicircular canal fistula (n = 24)
Type | n |
I | (91.7%) |
IIa | 12 (4.2%) |
IIb | 1(4.2%) |
III | 2(8.3%) |
We classified the semicircular canal fistula according to the Milewski & Dornhoffer classification: nine fistulas were type I (37.5%), 12 fistulas were type IIa (50%), one fistula was type IIb (4.2%), two fistulas were type III (8.3%) (Table 3). Type I.
In 21 cases, semicircular canal fistulas were closed with temporalis fascia and bone paste (bone dust mixed with fibrin glue) or conchal cartilage, while in three cases the fistulas were closed with temporalis fascia only.
Vertigo improved in 17 out of the 19 cases with semicircular canal fistula accompanying vertigo.
Complications such as facial-nerve paralysis or meningitis did not occur in any cases.
After surgery, vertigo worsened in one case and bone-conduction hearing level deteriorated by more than 10 dB hearing level in six cases.
Case reports
Case1: A 9-year-old male with left middle ear cholesteatoma.
He had semicircular canal fistula diagnosed by preoperative CBCT scan (Fig1-3).
The bony labyrinth was destroyed and endosteum exposed (Fig.4).
Fig. 1 and Fig. 2. Pre-operative MDCT scan of of left temporal bone in axial and coronal views, no fistula is apparent in the lateral semicircular canal.
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Fig. 3. Pre-operative CBCT scan, showing erosion of the otic capsule with lateral semicircular canal fistula.
Fig. 4. The bony labyrinth was destroyed and the endosteum exposed.
Case2: A 37-year-old male with left middle ear cholesteatoma.
Destruction was found in lateral semicircular canal and anterior semicircular canal (Fig.5).
The bony and membranous labyrinth was destroyed by cholesteatoma (Fig.6).
Type III of Milewski & Dornhoffer classification was diagnosed in this patient.
Fig. 5. Pre-operative CBCT scan, showing erosion of the otic capsule with lateral semicircular canal fistula.
Fig. 6. The bony and membranous labyrinth were destroyed by cholesteatoma.
Discussion
In our study, only 50% of all patients were positive for fistulas and the diagnosis of semicircular canal fistula was made in 91.7% pre-operatively.
Since a perfect pre-operative diagnosis of LF is not possible, the surgeon needs to be prepared for unexpected fistulas. Peltonen2 reported that CBCT was effective at the diagnosis of middle-and inner-ear areas. In our study, two ears misdiagnosed by MDCT were correctly diagnosed with labyrinthine fistula by pre-operative CBCT. For preservation of hearing and labyrinthine function, sealing the fistula with temporalis fascia and hard tissue are important.
Pre-operative diagnosis using CT imaging and surgical closure of the fistula with temporalis fascia and hard tissue are important in treatment of semicircular canal fistula with middle ear cholesteatoma.
References
1.Dornhoffer JL, Milewski C. Management of the open labyrinth. Otolaryngol Head Neck Surg 112(3):410–414, 1995
2.Peltonen LI, Aarnisalo AA, Kortesniemi MK, Suomalainen A, Jero J, Robinson S. Limited cone-beam computed tomography imaging of the middle ear: a comparison with multislice helical computed tomography. Acta Radiol 48(2):207–212, 2007
Address for correspondence: Takamichi Matsui, Department of Otolaryngology, Fukushima Medical University, 1 Hikarigaoka, Fukushima City, 960–1295, Japan. tamatsui@fmu.ac.jp
Cholesteatoma and Ear Surgery – An Update, pp. 393–397
Edited by Haruo Takahashi
2013 © Kugler Publications, Amsterdam, The Netherlands