Internal auditory canal metastasis - Acta Otorhinolaryngologica Italica

ACTA OTORHINOLARYNGOL ITAL 24, 78-82, 2004
Internal auditory canal metastasis
Le metastasi del condotto uditivo interno
M. FALCIONI, E. PICCIRILLO, G. DI TRAPANI, G. ROMANO, A. RUSSO
Gruppo Otologico, Piacenza-Roma, Italy
Key words
Tumours of the ear • Internal auditory canal neoplasms •
Metastasis
Summary
Parole chiave
Tumori dell’orecchio • Neoplasie del condotto uditivo interno • Metastasi
Riassunto
This report deals with 3 cases of internal auditory canal metastasis, an extremely rare lesion, few cases having been reported in the international literature. Since pre-operative diagnosis is fundamental in the planning of a correct therapeutic strategy, it is important that the neurotologist be aware of the possibility of their occurrence in this particular area. Metastasis
can occur unilaterally as well as bilaterally; the latter being the
case in 1 of the patients described herein. Correct pre-operative diagnosis is particularly difficult in patients in whom the
primary tumour has not been detected at the time of identification of the lesion in the internal auditory canal. The only characteristic, specific of metastasis, is the presence of multifocal
cerebral lesions. However, these were detected in only 1 of the
present cases. On the contrary, in cases of a single metastasis,
both magnetic resonance imaging and computed tomography
usually fail to show any distinctive feature when compared to
the most common tumours of the internal auditory canal (vestibular schwannomas and meningiomas). Bilateral metastases
can also be misdiagnosed as neurofibromatosis type 2. Clinical data that should alert the clinician are: rapidly progressive
sensorineural hearing loss, followed by onset of progressive
facial nerve weakness. Radiotherapy and/or chemotherapy are
the two main treatment modalities, while surgical removal is
reserved for selected cases of a single metastasis. Albeit, due
to the paucity of specific radiological and clinical characteristics, surgical removal is often necessary to reach the correct
diagnosis, as occurred in 2 of the present patients.
In questo lavoro sono riportati 3 casi di lesioni metastatiche a livello del condotto uditivo interno. Si tratta di
lesioni estremamente rare, con pochissimi casi riportati
nella letteratura internazionale; tuttavia è importante che
il neurotologo sia a conoscenza della possibilità dell’insorgenza di lesioni metastatiche a questo livello, in quanto
la diagnosi preoperatoria è fondamentale per la pianificazione di una corretta strategia terapeutica. Le metastasi
possono manifestarsi sia mono che bilateralmente; questa
ultima eventualità si è verificata in 1 dei nostri 3 casi. Il
raggiungimento di una corretta diagnosi preoperatoria è
spesso difficile, soprattutto nei pazienti in cui il tumore
primitivo è sconosciuto al momento dell’identificazione
della lesione a livello del condotto uditivo interno. L’unica
caratteristica specifica delle metastasi è la presenza di
lesioni multifocali a livello cerebrale. Tuttavia tali lesioni
erano presenti in 1 caso soltanto tra i nostri pazienti. Al
contrario in caso di metastasi singole sia la TC che la RMI
generalmente non evidenziano caratteristiche distintive
rispetto alle più comuni lesioni del condotto uditivo interno
(neurinomi dell’acustico e meningiomi). Anche le metastasi bilaterali possono essere confuse con casi di neurofibromatosi tipo 2. Il dato clinico che deve allertare il medico
è l’insorgenza di un’ipoacusia rapidamente progressiva a
cui si associa in successione un deficit del nervo facciale.
La radioterapia e/o la chemioterapia rappresentano le due
principali modalità di trattamento, mentre la rimozione
chirurgica è riservata a casi selezionati di metastasi
singole. Tuttavia a causa della rara presenza di caratteristiche cliniche o radiologiche specifiche delle metastasi
l’exeresi chirurgica è spesso richiesta per il raggiungimento
della corretta diagnosi, come accaduto in 2 dei nostri casi.
Introduction
agnosis is fundamental for correct planning of the
therapeutic strategy. However, in the majority of cases, diagnosis may be extremely demanding, since
metastasis may present clinical and radiological features indistinguishable from other lesions of the IAC
and CPA.
In the present report, 3 patients diagnosed with
metastasis in the IAC, at our centre, between 1987
and 2002, are described.
Internal auditory canal (IAC) and cerebellopontine
angle (CPA) metastases are extremely rare lesions
and account, according to Brackmann and Bartels 1,
for 0.2% of all CPA neoformations.
Although very rare, the neurotologist should take into consideration the possibility of secondary metastatic deposits in these areas, since the pre-operative di-
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INTERNAL AUDITORY CANAL METASTASIS
Case reports
CASE N. 1
A 53-year-old female who came to our attention in
March 1999 complaining of sudden left hearing loss
(HL), progressive right-sided sensorineural HL and
progressive left facial nerve (FN) weakness over the
last 5 months. In July 1997, the patient had a total
hysterectomy for a squamous cell carcinoma (SCC)
of the uterine cervix followed by adjunctive
chemotherapy.
Clinical evaluation showed negative otoscopy bilaterally with a complete FN palsy on the left side. Audiometric evaluation revealed a dead ear on the left
side and a right-sided sensorineural HL (mean PTA
40 dB, SDS 60%). Cerebral MRI showed the presence of a bilateral IAC lesion (Fig. 1). Both lesions
were hypointense on T1 and hyperintense on T2 sequences, with a homogeneous enhancement after
gadolinium infusion. The clinical and radiological
evaluation was highly suspicious of a bilateral IAC
metastasis, with the only other possible diagnosis being neurofibrobatosis type 2. In order to confirm the
diagnosis, in agreement with the patient, it was decided to remove the left-sided lesion through an enlarged translabyrinthine approach (March 22, 1999).
During surgery, the facial nerve was found to be considerably infiltrated by the tumour and had to be resected. Frozen section biopsy results revealed a
metastatic SCC. Surgery was then concluded with total removal of the lesion without FN reconstruction.
The patient, discharged on the third post-operative
day without any further complications, was referred
to a Department of Oncology where she underwent
stereotactic radiotherapy for the other lesion and the
area of surgical removal. In the meantime, a rightsided FN palsy developed. No other metastases were
discovered. The patient underwent serial radiological
follow-up and, 16 months after surgery, there was no
recurrence on the operated site; however, the contralateral lesion grew into the CPA, infiltrating the
midbrain and producing a marked perifocal oedema
(Fig. 2). In addition, a new lesion, at the level of the
corpus callosum, was discovered.
The patient’s conditions progressively deteriorated
until she was bedridden and died in August 2001, 30
months after surgical removal of the left-sided metastasis.
CASE N. 2
A 50-year-old female who came to our attention in
January 2001, complaining of vertigo spells, rightsided tinnitus and HL of 1 year’s duration. In addition, a rapidly progressing right FN weakness had appeared over the last month. Otoscopic examination
was negative, bilaterally. On clinical examination,
the FN deficit on the right side was classified as
79
Fig. 1. Cerebral MRI with gadolinium, axial section: bilateral IAC lesions with minimal CPA extension.
Fig. 2. Post-operative cerebral MRI with gadolinium, axial section: growth of the lesion with brainstem infiltration and oedema. Absence of signs of contralateral recurrence.
House Brackmann grade III. Audiometric evaluation
showed a dead ear, on the right side, and normal
hearing, on the left. At MRI, a lesion filling the IAC
was clearly visible, with lateral extension to the
geniculate ganglion and inner ear. This lesion was
hypointense on T1 and hyperintense on T2 sequences, with a homogeneous enhancement after
gadolinium infusion (Figs. 3, 4). Clinical history was
negative for any previous neoplastic disease. The tumour was removed January 31st, 2001, through a
transotic approach, in order to control the entire lesion from the IAC to the geniculate ganglion. Intraoperatively, the FN was found involved in the intracanalicular, intra-labyrinthine and geniculate ganglion areas. The lesion showed infiltration of all the
components of the VII-VIII nerve bundle; however,
since total removal was easily achieved, no intra-operative histological examination was required. The
intra-cysternal segment of the nerve appeared intact
M. FALCIONI, ET AL.
differentiated epithelial malignant neoplasm”. The
patient was then sent to the Department of Oncology
in order to locate the primary lesion, which was a
lung tumour. Despite chemotherapy, the patient died
8 months after surgery.
CASE N. 3
A 71-year-old male patient came to our attention complaining of progressive left-sided HL and tinnitus of 2
months’ duration. History was positive for otalgia and
unsteadiness. Clinical examination was negative, but
audiological tests showed a left-sided sensorineural
HL (PTA 55dB). The patient underwent cerebral MRI
that revealed an IAC lesion, with a hypointense signal
on T1 and T2 sequences, and enhancement after
gadolinium infusion (Fig. 5). Three other small enhanced areas were also present in the brain, 2 in the
frontal lobe and 1 in the left temporal lobe, the latter
showing a surrounding area of oedema (Fig. 6). The
radiological examination strongly suggested the presence of plurimetastatic lesions.
Fig. 3. Cerebral MRI with gadolinium, axial section: IAC lesion with vestibule involvement.
Fig. 5. Cerebral MRI with gadolinium, coronal section:
IAC lesion.
Fig. 4. Cerebral MRI with gadolinium, axial section: enhancement of geniculate ganglion area.
and thus reconstruction, by means of a sural nerve
graft, was accomplished.
The patient was sent home on post-operative day 5.
Definitive histological examination revealed “poorly
Fig. 6. Cerebral MRI with gadolinium, axial section: other
metastatic location at level of temporal lobe.
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INTERNAL AUDITORY CANAL METASTASIS
Total body CT scan located the primary tumour in the
prostate and revealed the presence both of bony and
lung metastases. In the meantime, the HL progressed
to anacusis and ipsilateral FN weakness (grade III)
appeared.
Two months after attempted chemotherapy, the patient died from intra-cerebral haemorrhage.
Discussion
IAC metastases are very rare lesions accounting for
only a small fraction (1.6%) of the IAC tumours submitted to surgery at our center between 1987 and
2002 (107 vestibular schwannomas, 10 meningiomas,
5 haemangiomas and 1 lipoma). Both unilateral and
bilateral IAC metastases have been reported in the
literature 2-4. As with other sites, IAC metastases can
occur in patients in whom the primary lesion has already been detected or may present as the first sign
of the disease. However, the presence of a malignant
tumour, in the clinical history of a patient with an
IAC lesion, strongly suggests the presence of metastasis.
Breast, lung, prostate, kidney and colon are reported to
be the most common sites of the primary lesion 2 3 5.
IAC and APC are rarely involved by spreading of
melanomas and lymphomas 3 6. When the metastasis
is the first sign of the disease, correct pre-operative
diagnosis may be particularly demanding. In fact, the
symptoms and radiological aspect may be completely non specific and common to every IAC and CPA
lesion. The main features that should alert the
otoneurosurgeon are: rapid progression of hearing
loss 2 3 5 7 and the frequent association with facial
weakness. In fact, the most common tumours of the
IAC (vestibular schwannomas and meningiomas)
present, in the majority of cases, with slow progressive hearing loss or with a sudden hearing loss, and
only, in few instances, they cause a FN deficit. On
the contrary the latter is often found in the presence
of metastasis, appears a short time after the onset of
hearing loss, and shows rapid progression to complete palsy.
Schwannomas and hemangiomas of the FN nerve are
the lesions frequently responsible for facial palsy.
However, in these cases, progression of the FN
weakness is usually very slow.
In 2 of our cases, a fast deterioration of hearing loss
was observed, while in the third case, affected by bilateral metastases, the hearing loss appeared suddenly, on one side, and progressively on the other. FN
deficit quickly deteriorated in all 3 cases and occurred a few weeks after the onset of the hearing loss.
In the majority of the cases, cerebral MRI with
gadolinium fails to distinguish between metastasis
and other neoformations of the IAC 6.
81
When bilateral IAC lesions are present, neoplastic
spread should be suspected, with the neurofibromatosis type 2 being the only possible alternative diagnosis. Albeit, the simultaneous presence of other
intra-parenchymal cerebral lesions is diagnostic for
neoplastic spread.
The main neuro-radiological characteristics of cerebral metastases are parenchymal infiltration and perifocal oedema. In the case of IAC metastases, these
radiological signs are evident only when the mass extends to the CPA, as in the final progression, in one
of our cases. When the lesion is limited to the IAC, it
is very difficult to distinguish the metastasis from a
benign tumour since they present the same neuro-radiological features (hypo-iso intensity in T1, slight
hyper-intensity in T2, gadolinium enhancement). Radiological signs reported in the literature, such as
slight and dyshomogeneous enhancement, after
gadolinium infusion, are very difficult to detect 8. For
this reason, it is not uncommon for the diagnosis of
IAC metastasis to be made only during or after the
operation, as in 2 of our cases.
High resolution CT scan, as for the other diseases
confined to the IAC and CPA, does not provide any
additional details, useful for the diagnosis. The only
exceptions are the cases with extension into the Fallopian canal, where CT scan can confirm and visualize the extension through enlargement of the Fallopian canal itself. Again, the radiological features are
similar to those of an intrinsic tumour of the FN, with
no specific features of the metastasis. Once the diagnosis of IAC metastasis is made, treatment has to be
arranged with an oncologic centre. When bilateral or
multiple metastasis are present, radiotherapy combined with chemotherapy is the treatment of choice.
In selected cases of an isolated single metastasis, surgical removal may be indicated. It should be stressed
that, regardless of the treatment modality, survival of
these patients is often in the range of a few months.
Only one case with a 5-year survival 9 has been reported in the literature.
Conclusions
IAC metastases are very rare lesions in which diagnosis may be extremely difficult. Except in the presence of multifocal lesions, neither MRI nor CT scan
are able to elicit distinctive features. The clinical sign
that must alert the ENT specialist is the presence of a
rapidly progressive HL combined with the onset of a
FN deficit with a fast evolution. Treatment is based
mainly upon stereotactic radiotherapy combined with
chemotherapy, while surgery is reserved only for selected cases presenting a single metastasis. However,
surgical removal is often necessary in order to reach
the correct diagnosis.
M. FALCIONI, ET AL.
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Received: July 14, 2003
Accepted: January 28, 2004
Address for correspondence: Dr. E. Piccirillo, Gruppo Otologico, via Emmanueli 42, 29100 Piacenza, Italy. Fax: +39
0523 453708.
E-mail: [email protected]
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