FACIAL-NERVE TUMOR COMBINED WITH CHOLESTEATOMA

Kazuo Ishikawa, Eigo Omi, Teruyuki Sato, Kohei Honda, Shinsuke Suzuki

Department of Otorhinolaryngology, Head-Neck Surgery, Graduate School of Medicine, Akita University, Akita, Japan

Case 1

A 37-year-old male with facial weakness and hearing loss on the right side. In August, 2009, he felt abnormal blinking of his right eye and complained of drooling while eating. He consulted a nearby ENT doctor, who performed a CT scan and suspected a facial nerve neuroma. The patient was then referred to our hospital for further treatment.

Clinical examinations

At the initial examination, a very tiny retraction pocket at pars flaccida of his right tympanic membrane was noted along with a mixed hearing loss of 38.8 dB (a+2b+c/4) hearing level. His left ear was normal. His facial nerve palsy was evident as shown in Figure 1, which was evaluated as Class V of the House-Brackman Grading System. The value of electro-neuronography (ENoG) was 5%. A CT scan revealed a small space-taking mass in the epitympanic space, with bony erosion at the base of the middle cranial fossa (Fig. 2a). Also a labyrinthine portion of the facial nerve became somewhat wider, and a small fistula was found at the basal turn of the cochlear (Fig. 2b). MRI showed that the main location of the space-taking lesion with peripheral enhancement (Fig. 3a) was at the horizontal portion of the facial nerve, extending to surrounding bony tissue, including the semicircular canal (Fig. 3b). Based upon these radiological findings, we thought that the most likely diagnosis could be intra-tympanic facial-nerve neuroma.

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Fig. 1. Evident right facial nerve palsy.

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Fig. 2. CT findings. a: epi-tympanic mass lesion with bony erosion; b: small cochlear fistula.

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Fig. 3. MRI findings with contrast enhancement. a: coronal view showing the lesion (open circle); b: axial view showing the lesion (open circle).

Operation

An inverted S-shaped incision from the temporal portion to the retro-auricular region was made to give access to the middle cranial fossa and mastoid. The lower part of the incision was extended to just below the mandibular angle for facial-nerve reconstruction. When opening the epi-tympanic space from the middle cranial base, the facial-nerve tumor embedded in the cholesteatoma was found and removed. The facial nerve was severed from the labyrinthine portion to the horizontal portion. During this manipulation, especially while elevating the labyrinthine portion of the facial nerve, a cochlear fistula was confirmed and sealed by fascia. By frozen section during the surgery, the incised edge of the facial nerve was found to be free from tumor cells. Then by trans-mastoid approach, the vertical portion of the facial nerve was exposed and elevated, followed by performing a facial nerve-hypoglossal nerve end-to-side anastomosis. A large defect of the MCF base was covered by free cortical bone.

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Fig. 4. Pathological findings (HE: Hematoxylin Eosin Staining). a: sample taken from the tumor: schwannoma; b: one sample of cholesteatoma.

Post-operative histology of the removed specimen demonstrated that the tumor was a combination of facial-nerve neuroma and cholesteatoma (Fig. 4A,B).

Discussion

It is quite rare that a facial-nerve tumor and cholesteatoma coexist in the tympanic cavity. The pathology in this case caused facial-nerve palsy and mixed hearing loss, although it might be difficult to make a correct diagnosis based upon the clinical findings obtained above before surgery.1 However, Sellari-Franceschini reported that the presence or absence of ossicular-bone erosion could be an important finding to differentiate cholesteatoma from other tumors.2 When considering the findings of ossicular erosion and a tiny retraction pocket, it could have been possible to suspect cholesteatoma along with a facial-nerve tumor. In this case, careful image study could have led to the correct diagnosis. As for the surgical approach, it could have been performed through trans-mastoid approach, but we selected a combined approach of middle cranial fossa and trans-mastoid. In this case, this combined approach should be safe, albeit invasive to some extent, considering unexpected laceration of the dura mater during dissecting tumor and cholesteatoma. Pre-operatively, we have noticed that the tumor eroded the bony wall of the basal turn of the cochlear to some degree, and thought that the tumor could be elevated from this part. It appeared that the patient lost his hearing post-operatively, which shows that it is quite difficult to preserve hearing acuity in cases of cochlear fistula.3 When considering the nature of this tumor, operative manipulation of the cochlear fistula should not have been performed and the tumor removal from the geniculate ganglion to the pyramidal portion might be sufficient to preserve hearing. Finally, regarding the facial-nerve reconstruction after the facial-nerve tumor removal, the vertical portion of the facial nerve was elevated and then the hypoglossal nerve was exposed. The stump of the facial nerve was sutured with epineurium of the hypoglossal nerve (end-to-side anastomosis) with 9–0 nylon. We have already reported that this method, if properly done, might show fairly well recovery with minimum associated movement.4

References

1.Watts A, Fagan P. The bony crescent sign – a new sign of facial nerve schwannoma. Australas Radiol 36:305–307, 1992

2.Sellari-Franceschini S, Berrettini S, Bruschini P, Scazzeri F, Nenci R, Ferrito G. Neuroma of the facial nerve masked by chronic otitis media. Am J Otol 15:441–444, 1994

3.Gamoletti R, Sanna M, Zini C, Taibah AK, Pasanisi E, Vassalli L. Inner ear cholesteatoma and the preservation of cochlear function. J Laryngol Otol 104:945–948, 1990

4.Teruyuki Sato, Weng Hoe Wong, Kazuo Ishikawa. Clinical study of six cases with facial nerve schwannoma. Facial N Res Jpn 27:235–237, 2007


Address for correspondence: Kazuo Ishikawa, ishioto@med.akita-u.ac.jp

Cholesteatoma and Ear Surgery – An Update, pp. 67–70

Edited by Haruo Takahashi

2013 © Kugler Publications, Amsterdam, The Netherlands