Auris·Nasus·Larynx (Tokyo) 19, 223-227 (1992)
INTRATEMPORAL FACIAL NERVE NEURINOMA WITHOUT FACIAL PARALYSIS Yozo 0KABE, M.D., lkuo NAGAYAMA, M.D., Tetsuya TAKIGUCHI, M.D., and Mitsuru FURUKAWA, M.D. Department of Otorhinolaryngology. School of Medicine. Kanazawa University, Kanazawa, Japan
A 38-year-old man was referred by his general practitioner to our department on 28 October 1991, with a 2-week history of vertigo. A left aural polyp was identified. The audiogram showed a moderate conductive loss on the left side. Computed tomography (CT) and magnetic resonance imaging (MRI) confirmed the presence of the expanding lesion in the descending portion of the facial nerve. However, there was no seventh nerve paresis. At operation, the neurinoma (Schwannoma) filled the middle ear cleft and extended from the genu to the stylomastoid foramen. The floor of the middle ear had been eroded, exposing the jugular bulb. Facial nerve paresis is the usual presenting feature of a facial neurinoma. The case is presented for the reason that the absence of facial palsy as a presenting feature is rather rare, especially in the cases with large tumor and extensive bone erosion.
CASE REPORT A 38-year-old man was referred to the Ear, Nose, and Throat Clinic of Kanazawa University on 28 October 1991, with 2-week history of vertigo. There was no history of facial weakness. He had noticed a moderate hearing disturbance and pulsating tinnitus on the left side for 1 year. Examination showed a left aural polyp completely occluding the left meatus. His audiogram showed a moderate conductive loss on the left side. The equilibrium function tests were performed before the surgery during his admission to our hospital. Neither spontaneous nystagmus nor positioning nystagmus was found. The fenestration phenomenon was negative. The stepping test showed slight deviation toward the affected side. The eye tracking test (ETT), and the optokinetic nystagmus test (OKN) were within normal limits. The caloric test showed a Received for publication January 24, 1992
223
Y. OKABE et a!
224
Fig. I.
Fig. 2.
CT scan. Intratemporal tumor is shown.
MR image finding. The tumor enhanced markedly after gadolinium injection.
slightly reduced response to the ice water on the left side, but it was considered to be because of the occlusion of the left meatus. CT scans confirmed the presence of the expanding lesion in the descending portion of the facial nerve and suggested that the mass had eroded into the mastoid air cells and middle ear cavity. Bony septum of the jugular bulb was also eroded and wide exposure of the posterior cranial fossa dura was suspected (Fig. 1). The bony capsule of the inner ear was not destroyed. The tumor was lower intensity on Tl-weighted MRI, and higher intensity on T2-weighted MRI than the cerebrum. Gd-DTPA enhancement of the tumor was
FACIAL NERVE NEURINOMA WITHOUT PARALYSIS
Fig. 3.
Fig. 4.
225
Internal carotid artery angiography. Normal findings.
Diagrammatic representation of facial nerve neurinoma.
evident (Fig. 2). The internal carotid artery angiography was within normal findings and therefore, a hypervascular tumor such as a hemangioma or a glomus tumor was not suspected (Fig. 3). At operation, the radiological findings were confirmed. Via a post-aural incision, and a transmastoid approach, the tumor was exposed (Fig. 4). The ossicles were surrounded by the tumor which completely filled the middle ear cleft. The horizontal and descending portion of the facial canal was grossly expanded. Bony structure surrounding the tumor was extensively eroded and the jugular bulb
226
Y. OKABE et al
Fig. 5.
Section of facial nerve neurinoma. Hematoxylin and eosin;
X
100.
was exposed. The patient did not suffer from vertigo after the surgery. However, the conductive hearing loss persisted on the almost same level as before, because of the removal of the malleus and the incus. Total facial palsy occurred after the surgery and a hypoglossal-facial nerve crossover was performed 3 weeks later. Histology (Fig. 5) revealed a variably cellular spindle cell tumor with several foci of palisading of nuclei, the appearances conforming to those of a neurinoma (Antoni A type). Some mitoses were found but the tumor was pathologically diagnosed to be benign. Verocay bodies were also found in every field of the microscopic specimen. In the stump of the facial nerve, degeneration and hyalinization of the nerve were revealed. DISCUSSION
The first case of intratemporal facial neurinoma was reported by Schmidt in 1931. 1 Since then, 183 cases have been reported. 2 A slowly progressive facial palsy is the predominant feature in such cases. Although the majority of facial nerve neurinomas present with facial nerve paralysis, Komune et al noted that some patients have no facial nerve dysfunction. 3 They reviewed the location of tumors in 22 reported cases with no facial paralysis, and assumed that normally existing dehiscences of fallopian canal might account for why some patients have normal facial nerve function. In such cases the tumor most frequently arose from the horizontal segment of the facial nerve and was rather small. In our case, the tumor was very large and filled the middle ear cleft with extensive bone erosion without facial paralysis. We could find only a few similar cases. 4· 6 The possible explanations of this rather rare phenomenon are: ( 1) The growth of the tumor is extremely slow. This is the most reliable explanation.
FACIAL NERVE NEURINOMA WITHOUT PARALYSIS
227
However, neurinoma is a benign tumor and always grows slowly. So, this reason is not sufficient to explain the rare phenomenon. (2) The tumor abounds with blood supply, and pulsating stimuli to the bone causes its erosion gradually. It is certain that the tumor abounded with blood supply, because of the presence of pulsating tinnitus and the findings during the surgery. Although the pulsating stimuli are less destructive, repeating stimuli may cause the erosion of the bone. (3) Facial nerve fibers exist far from the area where the bone destruction occurred. This explanation is only a suspicion and was not confirmed pathologically. ( 4) The tumor produced some bone-destructing enzyme. This is nothing but a possibility. This explanation is not credible, because the ossicles were surrounded by the tumor, but showed no erosive change. In conclusion, explanations 1 and 2 are reliable. Preoperative diagnosis of the facial nerve neurinoma is difficult especially in the cases without facial paralysis. MRI investigations with Gd-DTPA enhancement seemed to be the best method for studying the intratemporal tumors. Doyon et al reported the characteristic appearance of the facial nerve neurinoma on MRI and assessed the importance for differential diagnosis from cholesteatomas. 7 Facial neurinomas enhanced markedly after gadolinium injection, but in cholesteatomas no contrast enhancement was observed. A glomus tumor must be in mind for the diagnosis of the extensive intratemporal tumor, and internal carotid artery angiography is essential. The authors would like to thank Dr. A. Kawashima, Department of Pathology, Kanazawa University School of Medicine, for his help in reviewing the histological slides. REFERENCES I. 2.
Schmidt C: Neurom des nervus facialis. Schweiz Med Wschr 61:190-191, 1931. Jung STK, Byung-Hoon J, Shea D, et al: Primary and secondary tumors of the facial nerve, a temporal bone study. Arch Otolaryngol 112:1269-1273, 1986. 3. Komune S, Okada S, Uemura T: Two cases of intratemporal facial nerve neurilemmomas. A uris Nasus Larynx 13:151-156, 1986. 4. Pou JW: Neurinoma (Schwannoma) of the facial nerve. Arch Otolaryngol 69:48-56, 1959. 5. Bailey CM, Graham MD: Intratemporal facial nerve neuroma: A discussion of five cases. J Laryngol Otol 97:65-72, 1983. 6. Sharp JF, Kerr AIG, Carder P, et a!: Facial Schwannoma without facial paralysis. J Laryngol Otol 103:973-975, 1989. 7. Doyon D, Chan KY, Attia M, et al: Magnetic resonance investigations of non-acoustic petrous lesions. Arch Otorhinolaryngol 246:265-268, 1989.
Request reprints to:
Dr. Y. Okabe, Department of Otorhinolaryngology, Kanazawa University, 13-1 Takaramachi, Kanazawa 920, Japan
INTRATEMPORAL FACIAL NERVE NEURINOMA WITHOUT FACIAL PARALYSIS Yozo 0KABE, M.D., lkuo NAGAYAMA, M.D., Tetsuya TAKIGUCHI, M.D., and Mitsuru FURUKAWA, M.D. Department of Otorhinolaryngology. School of Medicine. Kanazawa University, Kanazawa, Japan
A 38-year-old man was referred by his general practitioner to our department on 28 October 1991, with a 2-week history of vertigo. A left aural polyp was identified. The audiogram showed a moderate conductive loss on the left side. Computed tomography (CT) and magnetic resonance imaging (MRI) confirmed the presence of the expanding lesion in the descending portion of the facial nerve. However, there was no seventh nerve paresis. At operation, the neurinoma (Schwannoma) filled the middle ear cleft and extended from the genu to the stylomastoid foramen. The floor of the middle ear had been eroded, exposing the jugular bulb. Facial nerve paresis is the usual presenting feature of a facial neurinoma. The case is presented for the reason that the absence of facial palsy as a presenting feature is rather rare, especially in the cases with large tumor and extensive bone erosion.
CASE REPORT A 38-year-old man was referred to the Ear, Nose, and Throat Clinic of Kanazawa University on 28 October 1991, with 2-week history of vertigo. There was no history of facial weakness. He had noticed a moderate hearing disturbance and pulsating tinnitus on the left side for 1 year. Examination showed a left aural polyp completely occluding the left meatus. His audiogram showed a moderate conductive loss on the left side. The equilibrium function tests were performed before the surgery during his admission to our hospital. Neither spontaneous nystagmus nor positioning nystagmus was found. The fenestration phenomenon was negative. The stepping test showed slight deviation toward the affected side. The eye tracking test (ETT), and the optokinetic nystagmus test (OKN) were within normal limits. The caloric test showed a Received for publication January 24, 1992
223
Y. OKABE et a!
224
Fig. I.
Fig. 2.
CT scan. Intratemporal tumor is shown.
MR image finding. The tumor enhanced markedly after gadolinium injection.
slightly reduced response to the ice water on the left side, but it was considered to be because of the occlusion of the left meatus. CT scans confirmed the presence of the expanding lesion in the descending portion of the facial nerve and suggested that the mass had eroded into the mastoid air cells and middle ear cavity. Bony septum of the jugular bulb was also eroded and wide exposure of the posterior cranial fossa dura was suspected (Fig. 1). The bony capsule of the inner ear was not destroyed. The tumor was lower intensity on Tl-weighted MRI, and higher intensity on T2-weighted MRI than the cerebrum. Gd-DTPA enhancement of the tumor was
FACIAL NERVE NEURINOMA WITHOUT PARALYSIS
Fig. 3.
Fig. 4.
225
Internal carotid artery angiography. Normal findings.
Diagrammatic representation of facial nerve neurinoma.
evident (Fig. 2). The internal carotid artery angiography was within normal findings and therefore, a hypervascular tumor such as a hemangioma or a glomus tumor was not suspected (Fig. 3). At operation, the radiological findings were confirmed. Via a post-aural incision, and a transmastoid approach, the tumor was exposed (Fig. 4). The ossicles were surrounded by the tumor which completely filled the middle ear cleft. The horizontal and descending portion of the facial canal was grossly expanded. Bony structure surrounding the tumor was extensively eroded and the jugular bulb
226
Y. OKABE et al
Fig. 5.
Section of facial nerve neurinoma. Hematoxylin and eosin;
X
100.
was exposed. The patient did not suffer from vertigo after the surgery. However, the conductive hearing loss persisted on the almost same level as before, because of the removal of the malleus and the incus. Total facial palsy occurred after the surgery and a hypoglossal-facial nerve crossover was performed 3 weeks later. Histology (Fig. 5) revealed a variably cellular spindle cell tumor with several foci of palisading of nuclei, the appearances conforming to those of a neurinoma (Antoni A type). Some mitoses were found but the tumor was pathologically diagnosed to be benign. Verocay bodies were also found in every field of the microscopic specimen. In the stump of the facial nerve, degeneration and hyalinization of the nerve were revealed. DISCUSSION
The first case of intratemporal facial neurinoma was reported by Schmidt in 1931. 1 Since then, 183 cases have been reported. 2 A slowly progressive facial palsy is the predominant feature in such cases. Although the majority of facial nerve neurinomas present with facial nerve paralysis, Komune et al noted that some patients have no facial nerve dysfunction. 3 They reviewed the location of tumors in 22 reported cases with no facial paralysis, and assumed that normally existing dehiscences of fallopian canal might account for why some patients have normal facial nerve function. In such cases the tumor most frequently arose from the horizontal segment of the facial nerve and was rather small. In our case, the tumor was very large and filled the middle ear cleft with extensive bone erosion without facial paralysis. We could find only a few similar cases. 4· 6 The possible explanations of this rather rare phenomenon are: ( 1) The growth of the tumor is extremely slow. This is the most reliable explanation.
FACIAL NERVE NEURINOMA WITHOUT PARALYSIS
227
However, neurinoma is a benign tumor and always grows slowly. So, this reason is not sufficient to explain the rare phenomenon. (2) The tumor abounds with blood supply, and pulsating stimuli to the bone causes its erosion gradually. It is certain that the tumor abounded with blood supply, because of the presence of pulsating tinnitus and the findings during the surgery. Although the pulsating stimuli are less destructive, repeating stimuli may cause the erosion of the bone. (3) Facial nerve fibers exist far from the area where the bone destruction occurred. This explanation is only a suspicion and was not confirmed pathologically. ( 4) The tumor produced some bone-destructing enzyme. This is nothing but a possibility. This explanation is not credible, because the ossicles were surrounded by the tumor, but showed no erosive change. In conclusion, explanations 1 and 2 are reliable. Preoperative diagnosis of the facial nerve neurinoma is difficult especially in the cases without facial paralysis. MRI investigations with Gd-DTPA enhancement seemed to be the best method for studying the intratemporal tumors. Doyon et al reported the characteristic appearance of the facial nerve neurinoma on MRI and assessed the importance for differential diagnosis from cholesteatomas. 7 Facial neurinomas enhanced markedly after gadolinium injection, but in cholesteatomas no contrast enhancement was observed. A glomus tumor must be in mind for the diagnosis of the extensive intratemporal tumor, and internal carotid artery angiography is essential. The authors would like to thank Dr. A. Kawashima, Department of Pathology, Kanazawa University School of Medicine, for his help in reviewing the histological slides. REFERENCES I. 2.
Schmidt C: Neurom des nervus facialis. Schweiz Med Wschr 61:190-191, 1931. Jung STK, Byung-Hoon J, Shea D, et al: Primary and secondary tumors of the facial nerve, a temporal bone study. Arch Otolaryngol 112:1269-1273, 1986. 3. Komune S, Okada S, Uemura T: Two cases of intratemporal facial nerve neurilemmomas. A uris Nasus Larynx 13:151-156, 1986. 4. Pou JW: Neurinoma (Schwannoma) of the facial nerve. Arch Otolaryngol 69:48-56, 1959. 5. Bailey CM, Graham MD: Intratemporal facial nerve neuroma: A discussion of five cases. J Laryngol Otol 97:65-72, 1983. 6. Sharp JF, Kerr AIG, Carder P, et a!: Facial Schwannoma without facial paralysis. J Laryngol Otol 103:973-975, 1989. 7. Doyon D, Chan KY, Attia M, et al: Magnetic resonance investigations of non-acoustic petrous lesions. Arch Otorhinolaryngol 246:265-268, 1989.
Request reprints to:
Dr. Y. Okabe, Department of Otorhinolaryngology, Kanazawa University, 13-1 Takaramachi, Kanazawa 920, Japan
