RESUMO

O Schwannoma do nervo facial (SNF) é o segundo tumor be-nigno mais frequente do ouvido médio. O seu tratamento écontroverso, uma vez que a parésia facial é quase sempre ine-vitável, após a ressecção cirúrgica. Esta decisão é particular-mente difícil nos doentes que se apresentam com parésialigeira.

Apresentamos dois casos de SNF do segmento timpânico, umnuma mulher de 40 anos e outro numa criança de 3 anos.Tendo em conta a parésia facial ligeira, foram propostos paramonitorização imagiológica e electrofisiológica.

As opções terapêuticas incluem a ressecção cirúrgica, a des-compressão, a radiocirurgia ou apenas observação. Os autoresdiscutem as vantagens e desvantagens de cada opção.

PALAVRAS-CHAVE: Nervo facial, Schwannoma, Ouvidomédio, Tratamento.

ABSTRACT

Facial nerve schwannoma (FNS) is the second most frequentbenign tumor of the middle ear. Its treatment is controversial,since facial paresis is almost always inevitable after surgical re-section. This decision is particularly difficult in patients whopresent with mild paresis.

We present two case reports of FNS of the tympanic segment,one in a 40 years old female and the other in a 3 years oldchild. Considering the slight degree of facial paresis, they wereproposed for imagiologic and electrophisiologic monitoring.Treatment options include surgical resection, decompression,radiosurgery or observation only. The authors discuss the ad-vantages and disadvantages of each option.

KEY-WORDS: Facial nerve, Schwannoma, Middle ear, Treat-ment.

ESPECIALIDADE CONVIDADA

SCHWANNOMA DO NERVO FACIAL:DILEMA TERAPÊUTICO

FACIAL NERVE SCHWANNOMAS:TREATMENT DILLEMAMiguel Viana; Paula Azevedo; Manuel Rodrigues e RodriguesServiço de Otorrinolaringologia do Hospital Pedro Hispano, Matosinhos, Portugal

Autor Responsável:

José Miguel Carvalho Viana

Hospital Pedro Hispano, Rua Dr. Eduardo Torres, 4464-513 Senhora da Hora

jmcviana1@gmail.com

18 Janeiro de 2012

FNS in the middle ear during exploratory tympanotomy.

FIG

1

CT and MRI with FNS in the tympanic segment of the facial nerve.

FIG

2

2 Cadernos Otorrinolaringologia . CLÍNICA, INVESTIGAÇÃO E INOVAÇÃO

: :INTRODUCTIONFacial nerve schwannoma (FNS) is the secondmost frequent be-nign tumor of the middle ear, after paraganglioma.1 Globally,FNS represents about 5% of the causes of facial paresis (FP), andup to 50% may not have paresis. In FNS located in the middleear the main manifestations, in addition to FP, are conductionhearing loss, tinnitus, ear fullness, otorrhea and aural polyp.1,2

Computerized tomography (CT) and magnetic resonance ima-ging (MRI) are important in the presumptive diagnosis of this en-tity. The imagiologic diagnosis is based on the topographiclocation of the lesion, bone changes and evidence of contrastuptake. MRI is more sensitive than CT in demonstrating this up-take.3

Treatment of these tumors is controversial, since PF is almost al-ways inevitable after surgical resection.4 This decision is particu-larly difficult in patients who present with a normal facialfunction or mild paresis. The authors present two case reports ofFNS of the tympanic segment.

: :CASE ONEA 40 years old female patient attended the emergency depart-ment because of sudden onset of right FP. She also reportedright hearing loss with around 3 years of evolution. Otoscopywas normal and acumetry showed negative Rinne on the right.In the physical examination, right peripheral FP, House-Brack-mann (HB) grade II, stood out. Audiogram showed moderateconduction hearing loss on the right. CT scan showed an opa-cifying mass involving the ossicular chain, adhering to the innerwall of the tympanic cavity. MRI showed expansion of the facialcanal and contrast uptake at the level of the geniculate ganglionand tympanic segment. It was proposed exploratory tympano-tomy for biopsy (figure 1), whose pathologic anatomy revealeda neoplasia of spindle cells without cytologic atypia or mitosisand with immunoreactivity for PS100 (compatible with schwan-noma). Considering the slight degree of facial paresis, the pa-tient was proposed for clinical and imagiologic monitoring. One

: :CASE TWOA 3 years old male patient was sent to the Otorhinolaryngo-logy consultation because of right FP present after birth, ini-tially, with progressive worsening, and at the moment stabilizedat a HB grade III FP. There were no other known neuro-otologicsymptoms. Otoscopy was normal. Brainstem auditory evokedpotentials presented a thresholds of 30 dB bilaterally. CT (fi-gure 2) scan revealed expansion of the right facial canal by softtissue mass that affected the second and third portions of FN.MRI (figure 2) showed right facial canal expansion and highcontrast uptake in the second and third portions of the nerve,suggestive of FN tumor (schwannoma). Patient was proposedfor clinical and imagiologic monitoring and, two years afterdiagnosis, his FP didn´t become worse.

year after the initial assessment, the patient remains stable wit-hout worsening. Electromyography (EMG) shows partial injury(axonotmesis) of the right facial nerve (FN), more severe in thelower branches, and absence of denervation activity (fibrillation).

Cadernos Otorrinolaringologia . CLÍNICA, INVESTIGAÇÃO E INOVAÇÃO 3

: :DISCUSSIONFNS is a rare tumor and treatment options include surgical re-section, decompression, radiosurgery or observation only.4,5

Some authors advocate observation in view of the benign na-ture and slow growth of these tumors.4 Another option is sur-gical decompression that allows expansion of the tumor anda slower rate of FP. The disadvantage of an expectant attitudeis the possibility of irreversible degenerative changes of thenerve and atrophy of muscle bundles.6 Observation with serialMRI and EMG is indicated in small tumors with reasonable fa-cial function (HB between grade I-III). Radiosurgery may beconsidered for control of tumor growth in elderly patients withhigh surgical risk, with good facial function and those withonly one ear.4 The ideal surgical candidate will be a patientwith progressive FP with HB grade equal or greater than III,and normal hearing in contralateral ear. Nerve integrity canbe preserved in up to 25% of cases.6 Previous histologicaldiagnosis, if possible, facilitates the discussion of treatmentoptions with the patient.

BIBLIOGRAPHY

1. Biswas D, Marnane CN, Mal RK, Baldwin DL. The presenting fea-

tures of middle ear facial nerve sheath tumors: a clinical review. Am

J Otolaryngol. 2008;29:58-62.

2. O'Donoghue GM, Brackmann DE, House JW, Jackler RK. Neuromas

of the facial nerve. Am J Otol. 1989;10:49-54.

3. Wiggins RH 3rd, Harnsberger HR, Salzman KL, Shelton C, Kertesz

TR, Glastonbury CM. The many faces of facial nerve schwannoma.

AJNR Am J Neuroradiol. 2006;27:694-9.

4. Chung JW, Ahn JH, Kim JH, Nam SY, Kim CJ, Lee KS. Facial nerve

schwannomas: different manifestations and outcomes. Surg Neu-

rol. 2004;62:245-52.

5. Kang GC, Soo KC, Lim DT. Extracranial non-vestibular head and

neck schwannomas: a ten-year experience. Ann Acad Med Singa-

pore. 2007;36:233-8.

6. Ulku CH, Uyar Y, Acar O, Yaman H, Avunduk MC. Facial nerve

schwannomas: a report of four cases and a review of the literature.

Am J Otolaryngol. 2004;25:426-31.