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Facial nerve schwannomas: Different manifestations and outcomes
Neoplasm
Facial Nerve Schwannomas: Different Manifestations and Outcomes Jong Woo Chung, M.D.,* Joong Ho Ahn, M.D.,* Jae Ho Kim, M.D.,* Soon Yuhl Nam, M.D.,* Chang-Jin Kim, M.D.,† and Kwang-Sun Lee, M.D.* *Department of Otolaryngology and †Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
Chung JW, Ahn JH, Kim JH, Nam SY, Kim C-J, Lee K-S. Facial nerve schwannomas: different manifestations and outcomes. Surg Neurol 2004;62:245–52.
preserved after the resection of the mass. One case showed complete loss of the peripheral branch of the facial nerve.
BACKGROUND
CONCLUSIONS
The purpose of this study was to provide data on the different clinical presentations of facial nerve schwannoma, the appropriate planning for the management of schwannoma of various origins, and the predictive outcomes of surgical management. METHODS
A retrospective study was conducted in a tertiary referral hospital. We reviewed 8 consecutive cases of facial nerve schwannoma diagnosed and managed between 1993 and 2001. RESULTS
Facial nerve schwannomas originated in the internal auditory canal (IAC) (2 cases), parotid gland (2 cases), intratemporal portion (3 cases), and stylomastoid foramen (1 case). Tumor of the stylomastoid foramen presented as an intra- and extratemporal mass. The initial presenting symptom of the 8 patients was facial nerve paralysis in 4 patients, hearing loss in 2, facial numbness in 1, and an infra-auricular mass in 1. Facial palsy occurred in 7 patients during the course of the disease. One patient with a mass in the parotid gland did not show facial palsy up to 1 year after presentation of the initial symptom (facial numbness). Facial nerve paralysis was most severe in intratemporal tumors and less severe in parotid tumors. The patients with IAC suffered from hearing loss and intermittent vertigo and showed decreased vestibular function. The patients with intratemporal tumors also complained of hearing loss. The tumors were completely removed by superficial parotidectomy for parotid tumors; the translabyrinthine approach for 1 IAC tumor and 1 intratemporal tumor; the middle fossa approach for the other IAC tumor; the transmastoid approach for mastoid tumors; and the infratemporal fossa approach for intratemporal and extratemporal tumors. End-to-end cable grafts for the facial nerve were performed in 5 out of 8 cases. In 2 cases, the facial nerve was Address reprint requests to: Jong Woo Chung, MD, Department of Otolaryngology, Asan Medical Center, 388-1 Pungnap-Dong Songpa-Gu, Seoul, 138-736, Korea. Received April 24, 2003; accepted September 22, 2003. © 2004 Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010 –1710
Facial nerve schwannoma can present in various ways. By examining the site of origin and the presenting symptoms and signs, we were able to diagnose facial nerve schwannoma preoperatively. According to the operative management of the facial nerve, the postoperative outcome of facial function could be estimated. Our finding could be pivotal in the management of the facial nerve schwannoma. © 2004 Elsevier Inc. All rights reserved. KEY WORDS
Facial nerve diseases, neurilemmoma, mastoid, parotid gland, facial paralysis.
chwannomas (neurilemomas) are benign, slow-growing neoplasms of neuroectodermal origin. These lesions arise from Schwann’s cells that ensheath axons of the peripheral, cranial, and autonomic nervous systems. The tumor originates in the nerve sheath in a focal manner as a solitary and well-encapsulated mass [17]. Because of the long complex course of the facial nerve, facial nerve schwannomas can originate in any segment of the nerve, from the glial-Schwann cell junction at the cerebellopontine angle to the peripheral branches in the face. Though most schwannomas usually originate in the labyrinthine and tympanic segments above the oval window [9,10,12,15], schwannomas can originate in any other portion of the nerve, such as the internal auditory canal (IAC) or extratemporal area [7,19]. Facial nerve schwannoma has various manifestations, including facial palsy, hearing loss, vestibular weakness, a palpable parotid mass, and even no symptom depending on its size and site [3,7,15]. Facial weakness and hearing loss are the most common presenting complaints [11], but there are also
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other symptoms and signs such as tinnitus, vestibular symptoms, or an infra-auricular mass [7,15]. Depending on the site involved, the surgical extent varies, as in the transmastoid, translabyrinthine, or middle fossa approaches. The facial nerve can be sacrificed or preserved depending on the degree of involvement [14,15]. If the facial nerve has to be sacrificed, there are several procedures that can restore facial function. However, postoperative facial function is variable. The purpose of this study was to provide data on different clinical presentations of facial nerve schwannomas, to suggest appropriate planning for the management of facial nerve schwannomas of various origins, and to predict outcomes of facial function after surgical management.
Materials and Methods We conducted a retrospective review of 8 patients who had been diagnosed with facial nerve schwannoma and managed between 1993 and 2001. Facial nerve function was evaluated with the HouseBrackmann facial nerve grading system [6]. The patients consisted of 2 men and 6 women. The age range was 21 to 60 years (average 44 years). Four cases had a right side lesion and 4 had a left lesion. Average follow-up was 58.3 months (range 10 –77 months). Facial nerve schwannomas originated in the parotid gland (2 cases), internal auditory canal (2 cases), intra-temporal portion (3 cases), and stylomastoid foramen (1 case). Tumors from the stylomastoid foramen presented as intraand extratemporal masses. All tumors were successfully removed and facial nerve continuity was preserved in 2 cases. CASE 1 A 31-year-old male presented with a palpable mass in the right parotid area of 5 years duration. The mass was slowly growing and he felt facial numbness on the right side of his face. Physical examination showed evidence of a mass 4 cm in diameter, which was round, fixed, and nontender during palpation. His facial expression was symmetrically intact. Magnetic resonance imaging (MRI) showed a 3 ⫻ 4 cm well-enhanced round mass in the right parotid area. The mass was removed together with the attached facial nerve, and the nerve was repaired with end-to-end anastomosis using the greater auricular nerve (Figure 1). Facial expression was normal and symmetric preoperatively (Grade I). Immediate postoperative facial function was grade VI and
MRI and intraoperative findings in Case 1. (A) An MRI showing a 3 ⫻ 4 cm well-enhanced round mass in the right parotid area (arrowheads). (B) A large mass originating from the facial nerve trunk (arrow). The mass was removed together with the attached facial nerve and the nerve was repaired with end-to-end anastomosis using the greater auricular nerve.
1
facial function improved gradually to Grade III over 9 months. There was no further improvement of facial function during the 6-year follow-up period. CASE 2 A 43-year-female presented with a right infraauricular mass and facial paralysis that she had experienced for 2 years. She also complained of hearing loss and intermittent otorrhea. The infra-auricular mass was 3 ⫻ 4 cm in size and multilobular, nontender, firm, and rather fixed. The tympanic membrane showed retraction of the whole membrane and keratin debris had drained from the attic. Pathologically, schwannoma was suggested by a preoperative fine needle aspiration biopsy. A temporal bone MRI showed a mass involving the entire mastoid cavity and infratemporal fossa. Coincidentally, cholesteatoma involving the
Facial Nerve Schwannoma
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upper respiratory infection (URI) symptoms, and hearing loss and vertigo suddenly developed, followed by facial palsy. Physical examination showed an intact tympanic membrane and facial palsy of House-Brackmann Grade IV. Audiometry showed profound sensorineural hearing loss, and vestibular function was decreased in his left ear. MRI showed a small, 1 ⫻ 2 cm, well-enhanced mass in the left internal auditory canal (Figure 3). The translabyrinthine approach was performed. The mass originated in the internal auditory canal of the facial nerve. The mass was removed together with the attached facial nerve, and the nerve was repaired by a cable graft between the intracranial and mastoid portions using the greater auricular nerve. Facial function was Grade VI immediately postoperatively and improved to Grade III over a 1-year follow-up. There was no further improvement in facial function until 4.5 years after the removal of the mass.
Results External appearance and intraoperative finding in Case 2. (A) A 4 ⫻ 5 cm large infra-auricular mass (arrowheads). (B) A large mass occupying the whole mastoid cavity and extending into the infratemporal fossa (arrows). There was no part of the facial nerve that was healthy. SS: sigmoid sinus, SCM: sternocleidomastoid muscle.
2
attic area was also noticed. The mass was completely removed using the infratemporal fossa approach. Intra-operative findings showed a large mass occupying the whole mastoid cavity with the mass extended and attached to the sigmoid sinus and jugular foramen. The facial nerve was not healthy throughout its entire course from the geniculate ganglion to the peripheral branches (Figure 2). Facial function was Grade VI preoperatively and immediately postoperatively. Before the operation pure tone average was 27 dB in air conduction and became 53 dB after the operation. Bone conduction was normal and did not change postoperatively. After a 5-year follow-up, facial expression had not changed significantly, but the upper eyelid moved a little, enough to cover the eyeball with maximal effort. CASE 3 A 21-year-old male presented with left side facial palsy of 20 days’ duration. He had previously had
The initial presenting symptom was facial nerve paralysis in 4 out of 8 tumors. One patient showed recurrent facial paralysis with some recovery. Seven out of 8 patients showed facial nerve paralysis during the course of the disease (Table 1). Facial nerve paralysis was most severe in intratemporal tumors and less severe in parotid tumors. Patients with IAC initially suffered from hearing loss and intermittent vertigo and showed decreased vestibular function. Patients with intratemporal tumors also complained of hearing loss. In 1 patient who did not experience facial paralysis, facial numbness was the only symptom until a parotid mass was found during a physical examination. Two patients with IAC masses also complained of sensorineural hearing loss with tinnitus, and they consulted a doctor earlier than the others because of the sudden onset of multiple symptoms. Three patients with intratemporal masses (including a case of an intra- and extratemporal mass) complained of conductive hearing loss with low-tone tinnitus. Tumors were completely removed by superficial parotidectomy in parotid tumors, the translabyrinthine approach in 1 IAC tumor, the middle fossa approach in the other IAC tumor, the transmastoid approach in mastoid tumors, and the infratemporal fossa approach in intratemporal and extratemporal tumors. There were no severe postoperative complications (Table 2). Facial nerves were sacrificed in 6 cases. Facialhypoglossal crossover technique was performed in
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MRI, intraoperative, and pathologic findings in Case 3. (A, B) Axial and coronal MRI showing a small 1 ⫻ 2 cm, well-enhanced mass in the left internal auditory canal (arrows). (C) Mass (*) originating from the facial nerve (arrow) in the internal auditory canal. The mass was removed together with the attached facial nerve and the nerve was repaired by a cable graft between the intracranial portion and mastoid portion (mFN) using the greater auricular nerve. (D) Pathologic finding (⫻200) showing a palisading array of nuclei around a central mass of cytoplasm (Verocay body, arrows). This finding was an Antoni A type.
3
2 cases of intratemporal schwannoma, and end-toend cable grafts using the greater auricular nerve were performed in 1 of each parotid and IAC schwannoma. End-to-end anastomosis with the sural nerve was applied in 1 case of intratemporal mass. In this case, the labyrinthine and meatal portion of the facial nerve were also involved, and the translabyrinthine approach was performed. The cable graft was performed between the IAC and facial nerve trunk in the parotid gland. In 1 patient, the mass involved all the peripheral branches, and facial reanimation surgery is planned. Facial nerves were able to be preserved after resection of the mass in 1 of the parotid cases and 1 IAC case. Facial expression improved in patients who received the facial nerve graft except for one case with an intact facial function at presentation. In the
cases of facial nerve preservation, facial function did not change postoperatively. The final facial expression was Grade III in the cases with the cable graft (GAN and sural nerve) and Grade IV in the cases with facial-hypoglossal cross-over (Table 2). MRIs were checked in all the patients except the last case at one year of follow-up, and there was no evidence of recurrence. Up to the last follow-up, there have been no specific symptoms or signs suggesting recurrence of the tumor.
Discussion Facial palsy is induced by various causes, with 50⬃80% of cases thought to be idiopathic [1]. Since Schmidt first reported a case of facial nerve
IV ⫹ (2 mos) ⫹ facial palsy hearing loss
2 mos
⫹
⫺
V ⫹ (7 yrs) ⫹ hearing loss, tinnitus
L 48 8
F
60 7
F
L
Internal auditory canal (IAC) Intratemporal (labyrinthine portion-stylomastoid foramen) Intratemporal (geniculate ganglion-stylomastoid foramen) Intra- & Extratemporal (IACfacial nerve trunk) R R 31 51 5 6
F F
L 21 4
M
10 yrs
⫹
⫺
III V ⫹ ⫹ ⫹ ⫹ 1 mo 8 yrs
⫹ ⫹
⫹ ⫹
IV ⫹ (1 mo) ⫹
hearing loss, vertigo facial palsy recurrent facial palsy
2 mos
⫹
⫹
I IV VI ⫺ ⫹ ⫹ (2 yrs) ⫺ ⫺ ⫺ ⫺ ⫺ ⫹ facial numbness facial palsy infra-auricular mass
Intraparotid Intraparotid Intra- & Extra-temporal (geniculate ganglion-distal branches) Internal auditory canal (IAC) R L R 31 47 43 1 2 3
M F F
SYMPTOM
INITIAL OF MASS
EXTENT SIDE AGE (YRS)
SEX
1 yr 2 yrs 2 yrs
TINNITUS LOSS
⫺ ⫺ ⫺
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NO
1
Demographic Data and Presentation of Facial Nerve Schwannoma Cases
DURATION
HEARING
ASSOCIATED
VERTIGO
SYMPTOMS
FACIAL PARALYSIS
FACIAL EXPRESSION
Facial Nerve Schwannoma
schwannoma, many authors reported a 0.15 to 0.8% prevalence of facial nerve schwannoma [13]. For a diagnosis of facial nerve schwannoma, one must put together many diagnostic tools, such as clinical aspect and radiologic and pathologic findings. As we discussed above, the clinical manifestations of facial nerve schwannoma vary depending on the site and size of the tumor mass. Facial palsy is a distinctive and relatively common symptom, having an 84% incidence in intratemporal tumors and 34% in extratemporal tumors [13]. But other investigators have reported that hearing loss and tinnitus were the most common symptoms, and facial palsy was found in only 45% of 48 cases [11]. In this study, 7 out of 8 cases (86%) had facial palsy of varying degree and hearing loss was found in 5 cases (71%). As for initial symptoms, only 4 out of 8 patients experienced facial paralysis. Another 4 patients initially suffered from hearing loss, vertigo, facial numbness, or facial mass. When the site of the lesion was categorized as intratemporal (including IAC) and extratemporal, we found few symptoms in extratemporal cases, but more than 3 symptoms, such as hearing loss, tinnitus, dizziness, and facial weakness or pain, in intratemporal cases. Based on this finding, intratemporal schwannoma showed more severe clinical manifestations. Recently, the development and improvement of radiologic technique, such as gadolinium-enhanced MRI, has made it possible to diagnose small facial nerve schwannomas earlier. MRI can differentiate facial nerve schwannoma from hemangioma, cholesterol granuloma, and meningioma [2,11]. In our series, all the facial nerve schwannomas were diagnosed with the help of a preoperative MRI scan and confirmed by pathologic examination. MRI was more helpful in facial nerve schwannomas within the IAC or mastoid cavity. Inside the IAC, facial nerve schwannoma could be differentiated from vestibular schwannoma by posterior displacement of the tumor relative to the IAC in MRI [5,11,15,16]. Other authors, however, have insisted that MRI could not reveal facial nerve tumors [8]. In our series, there were 2 cases of a tumor originating inside the IAC. MRI could not differentiate this mass from vestibular schwannoma because of a lack of evidence of posterior displacement. In the cases of vestibular schwannoma, only 3.2% of the patients were reported to have facial weakness at presentation [18], and the incidence of facial paralysis was greater for the larger tumors. On the contrary, facial nerve symptoms were more frequently observed (up to 73%) in the patients with facial nerve schwannoma at initial presentation
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2
Intra-Operative Findings and Follow-up Data
COMPLICATIONS OPERATIVE
FACIAL
NO
APPROACH
1
Superficaial parotidectomy Superficaial parotidectomy Infratemporal fossa approach
4 ⫻ 4 ⫻ 3 cm
Translabyrinthine approach Middle fossa approach Middle fossa and transmastoid approach Transmastoid approach Translabyrinthine approach
1 ⫻ 2 ⫻ 1 cm
2 3 4 5 6 7 8
MASS
SIZE
NERVE MANAGEMENT
FACIAL
NERVE GRAFT
IMMEDIATE
LATE
FACIAL
EXPRESSION
AT PRESENTATION
LAST
F/U
F/U
DURATION
Excision and anastomosis not sacrificed
End to end anastomosis with GAN graft –
–
–
I
III
6 yrs 6 mos
–
–
IV
IV
2 yrs 6 mos
Excision and no anastomosis Excision and anastomosis not sacrificed
–
wound dehiscence
–
VI
VI
5 yrs
End to end anastomosis with GAN graft –
keloid
keloid
IV
III
4 yrs 6 mos
–
–
III
III
4 yrs 4 mos
N/A**
Excision and anastomosis
VII–XII anastomosis
–
Tinnel sign
V
IV
6 mos
N/A**
Excision and anastomosis Excision and anastomosis
VII–XII anastomosis
–
–
V
IV
2 yrs
End to end anastomosis with sural nerve graft
–
–
IV
III
10 mos
2 ⫻ 2 ⫻ 2 cm 3 ⫻ 4 ⫻ 3 cm*
2 ⫻ 2 ⫻ 1 cm
3 ⫻ 3 ⫻ 2 cm
*Size of extratemporal mass, whole mastoid cavity was also filled with the mass. **Mass occupying whole mastoid cavity.
Chung et al
Facial Nerve Schwannoma
[4,9,11], such as sudden or gradual onset of facial paralysis and recurrent paralysis as shown in our cases. The patients who had a tumor originating inside the IAC in this study complained of hearing loss, vertigo, and facial palsy, which are indistinguishable from the symptoms of vestibular schwannoma. However, they experienced the early onset of facial palsy, and an electro-diagnostic test at 1 and 2 months after the onset of symptoms showed that more than 95% of the facial nerve had degenerated. Taken together, early onset of facial weakness is a suspicious sign of facial nerve schwannoma in the case of a tumor inside the IAC, and a high index of suspicion is needed to precisely diagnose facial nerve schwannoma. The aim of surgery in facial nerve schwannoma is complete tumor excision with preservation of the facial and hearing functions [11]. Therefore, it is very important to decide upon the location and size of the tumor, facial nerve function, and hearing before choosing the treatment method. We performed different surgical approaches in line with the location, size, and grade of invasion of the tumor. Theoretically, facial function could be preserved when the mass is removed with the facial nerve sheath without interrupting the nerve fibers [14]. We were able to preserve the facial nerve in 2 cases, but inevitably the facial nerve was sacrificed in the rest of the cases. Facial function gradually improved in cases with facial nerve grafts. The final grade of facial expression in patients with end-to-end facial nerve anastomsis with cable graft was grade III. In the cases of facial nerve preservation, there was no improvement of facial function. In other investigators’ series, when the facial nerve could be preserved, as, for example when a mass was located eccentrically on the nerve, 1 of 2 cases completely recovered facial function [15]. From these findings, we suggest that resection and anastomosis of the facial nerve is to be encouraged when facial function is worse than Grade III and graft materials are available. Also, end-to-end anastomosis is better than facialhypoglossal cross-over wherever possible. In the point of the postoperative facial function, the size of the mass could be a factor for the prediction of the function. Three cases in which the end-to-end cable graft was possible had smaller tumors than the other cases. From above, early surgical intervention was highly recommended. Hearing function could be preserved in all cases that had serviceable preoperative hearing. Three out of 8 cases had profound hearing loss, and the
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labyrinth was resected for the complete removal of the mass. There has been a lot of debate about the timing of surgical intervention for facial nerve schwannoma. Many authors have insisted that it is beneficial to operate as early as possible except in cases of poor general status or advanced age [11]. We also believe early surgical intervention and careful facial nerve anastomosis to be the best management of facial nerve schwannoma.
Conclusion Facial nerve schwannomas can present in various ways. Depending on the site of origin and presenting symptoms and signs, we were able to diagnose facial nerve schwannoma preoperatively. According to the operative management of the facial nerve, we could estimate the postoperative outcome of facial function. Our finding could be pivotal in the management of the facial nerve schwannoma. REFERENCES 1. Bleicher JN, Hamiel S, Gengler JS. A survey of facial paralysis: etiology and incidence. Ear Nose Throat J 1996;75:355–7. 2. Chen JM, Moll C, Wichmann W, Kurrer MO, Fisch U. Magnetic resonance imaging and intraoperative frozen sections in intratemporal facial nerve schwannomas. Am J Otol 1995;16:68 –74. 3. Chun YM, Park K, Lee JS, Chun SH. The management of facial nerve schwannoma. Kor J Otolaryngol 1997; 40:1052–7. 4. Dort JC, Fisch U. Facial nerve schwannomas. Skull Base Surg 1991;1:51–6. 5. Fagon PA, Misra SN, Doust B. Facial neuroma of the cerebellopontine angle and the internal auditory canal. Laryngoscope 1993;103:442–6. 6. House JW, Brackmann DE. Facial nerve grading system. Otolaryngol Head Neck Surg 1985;93:146 –7. 7. Kim CS, Sung MH, Hwang EG, Chung HW, Han MH. Surgical management of intratemporal facial nerve neurilemmoma. Kor J Otolaryngol 1989;32:391–408. 8. Lassaletta L, Roda JM, Frutos R, Patron M, Gavilan J. Facial nerve schwannoma of the cerebellopontine angle: a diagnostic challenge. Skull Base 2002;12:203–7. 9. Lipkin AF, Coker NJ, Jenkins HA, Alford BR. Intracranial and intratemporal facial neuroma. Otolaryngol Head Neck Surg 1987;96:71–9. 10. Nager GT. Pathology of the ear and temporal bone. Baltimore: Williams & Wilkins, 1993;597–9. 11. O’Donoghue GM, Brackmann DE, House JW, Jackler RK. Neuromas of the facial nerve. Am J Otolaryngol 1989;10:49 –54. 12. Pulec JL. Facial nerve neuroma. Ear Nose Throat J 1994;73:721–52. 13. Saito H, Baxter A. Undiagnosed intratemporal facial nerve neurilemmomas. Arch Otolaryngol 1972;95: 415–9. 14. Sataloff RT, Frattali MA, Myers DL. Intracranial facial
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15.
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neuromas: total tumor removal with facial nerve preservation: a new surgical technique. Ear Nose Throat J 1995;74:244 –56. Sherman JD, Dagnew E, Pensak ML, van Loveren HR, Tew JM. Facial nerve neuromas: report of 10 cases and review of the literature. Neurosurg 2002;50: 450 –6. Symon L, Cheesman AD, Kawauchi M, Bordi L. Neuromas of the facial nerve: a report of 12 cases. Br J Neurosurg 1993;7:13–22. Walter JB, Israel MS. Structure and effects of some common tumors. In: General pathology, 5th ed. Edinburgh: Churchill Livingstone, 1979;219 –20. Wiegand DA, Ojemann RG, Fickel V. Surgical treatment of acoustic neuroma (vestibular schwannoma) in the United States: report from the Acoustic Neuroma Registry. Laryngoscope 1996;106:58 –66. Yamaki T, Morimoto S, Ohtaki M, et al. Intracranial facial nerve neuroma: surgical stratage of tumor removal and functional reconstruction. Surg Neurol 1998;49:538 –46.
COMMENTARY
The authors report on 8 facial nerve schwannomas treated from 1993 through 2001. Nerve reconstruction was performed in 5 of 8 patients. The images
Chung et al
are of excellent quality, and the presented cases demonstrate the high variability in facial nerve schwannomas. Early surgical intervention in large tumors with facial nerve paresis of varying degrees, as in the series presented, is clearly indicated. Still, in this series one presentation of facial nerve schwannoma is missing: very small tumors, diagnosed with mild symptoms and without facial nerve paresis. When treating this patient group, the neurosurgeon faces difficult decisions. Early surgical intervention and careful nerve anastomosis might, in this patient group, not always be the best solution out of the physicians dilemma. The patients’ expectations, profession and particular situation have to be carefully analyzed before deciding about treatment options in this selected group of tumors. Wolf Lu ¨ demann, M.D., Madjid Samii, M.D. Ph.D. International Neuroscience Institute Hannover, Germany
Facial Nerve Schwannomas: Different Manifestations and Outcomes Jong Woo Chung, M.D.,* Joong Ho Ahn, M.D.,* Jae Ho Kim, M.D.,* Soon Yuhl Nam, M.D.,* Chang-Jin Kim, M.D.,† and Kwang-Sun Lee, M.D.* *Department of Otolaryngology and †Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
Chung JW, Ahn JH, Kim JH, Nam SY, Kim C-J, Lee K-S. Facial nerve schwannomas: different manifestations and outcomes. Surg Neurol 2004;62:245–52.
preserved after the resection of the mass. One case showed complete loss of the peripheral branch of the facial nerve.
BACKGROUND
CONCLUSIONS
The purpose of this study was to provide data on the different clinical presentations of facial nerve schwannoma, the appropriate planning for the management of schwannoma of various origins, and the predictive outcomes of surgical management. METHODS
A retrospective study was conducted in a tertiary referral hospital. We reviewed 8 consecutive cases of facial nerve schwannoma diagnosed and managed between 1993 and 2001. RESULTS
Facial nerve schwannomas originated in the internal auditory canal (IAC) (2 cases), parotid gland (2 cases), intratemporal portion (3 cases), and stylomastoid foramen (1 case). Tumor of the stylomastoid foramen presented as an intra- and extratemporal mass. The initial presenting symptom of the 8 patients was facial nerve paralysis in 4 patients, hearing loss in 2, facial numbness in 1, and an infra-auricular mass in 1. Facial palsy occurred in 7 patients during the course of the disease. One patient with a mass in the parotid gland did not show facial palsy up to 1 year after presentation of the initial symptom (facial numbness). Facial nerve paralysis was most severe in intratemporal tumors and less severe in parotid tumors. The patients with IAC suffered from hearing loss and intermittent vertigo and showed decreased vestibular function. The patients with intratemporal tumors also complained of hearing loss. The tumors were completely removed by superficial parotidectomy for parotid tumors; the translabyrinthine approach for 1 IAC tumor and 1 intratemporal tumor; the middle fossa approach for the other IAC tumor; the transmastoid approach for mastoid tumors; and the infratemporal fossa approach for intratemporal and extratemporal tumors. End-to-end cable grafts for the facial nerve were performed in 5 out of 8 cases. In 2 cases, the facial nerve was Address reprint requests to: Jong Woo Chung, MD, Department of Otolaryngology, Asan Medical Center, 388-1 Pungnap-Dong Songpa-Gu, Seoul, 138-736, Korea. Received April 24, 2003; accepted September 22, 2003. © 2004 Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010 –1710
Facial nerve schwannoma can present in various ways. By examining the site of origin and the presenting symptoms and signs, we were able to diagnose facial nerve schwannoma preoperatively. According to the operative management of the facial nerve, the postoperative outcome of facial function could be estimated. Our finding could be pivotal in the management of the facial nerve schwannoma. © 2004 Elsevier Inc. All rights reserved. KEY WORDS
Facial nerve diseases, neurilemmoma, mastoid, parotid gland, facial paralysis.
chwannomas (neurilemomas) are benign, slow-growing neoplasms of neuroectodermal origin. These lesions arise from Schwann’s cells that ensheath axons of the peripheral, cranial, and autonomic nervous systems. The tumor originates in the nerve sheath in a focal manner as a solitary and well-encapsulated mass [17]. Because of the long complex course of the facial nerve, facial nerve schwannomas can originate in any segment of the nerve, from the glial-Schwann cell junction at the cerebellopontine angle to the peripheral branches in the face. Though most schwannomas usually originate in the labyrinthine and tympanic segments above the oval window [9,10,12,15], schwannomas can originate in any other portion of the nerve, such as the internal auditory canal (IAC) or extratemporal area [7,19]. Facial nerve schwannoma has various manifestations, including facial palsy, hearing loss, vestibular weakness, a palpable parotid mass, and even no symptom depending on its size and site [3,7,15]. Facial weakness and hearing loss are the most common presenting complaints [11], but there are also
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0090-3019/03/$–see front matter doi:10.1016/j.surneu.2003.09.034
246 Surg Neurol 2004;62:245–52
Chung et al
other symptoms and signs such as tinnitus, vestibular symptoms, or an infra-auricular mass [7,15]. Depending on the site involved, the surgical extent varies, as in the transmastoid, translabyrinthine, or middle fossa approaches. The facial nerve can be sacrificed or preserved depending on the degree of involvement [14,15]. If the facial nerve has to be sacrificed, there are several procedures that can restore facial function. However, postoperative facial function is variable. The purpose of this study was to provide data on different clinical presentations of facial nerve schwannomas, to suggest appropriate planning for the management of facial nerve schwannomas of various origins, and to predict outcomes of facial function after surgical management.
Materials and Methods We conducted a retrospective review of 8 patients who had been diagnosed with facial nerve schwannoma and managed between 1993 and 2001. Facial nerve function was evaluated with the HouseBrackmann facial nerve grading system [6]. The patients consisted of 2 men and 6 women. The age range was 21 to 60 years (average 44 years). Four cases had a right side lesion and 4 had a left lesion. Average follow-up was 58.3 months (range 10 –77 months). Facial nerve schwannomas originated in the parotid gland (2 cases), internal auditory canal (2 cases), intra-temporal portion (3 cases), and stylomastoid foramen (1 case). Tumors from the stylomastoid foramen presented as intraand extratemporal masses. All tumors were successfully removed and facial nerve continuity was preserved in 2 cases. CASE 1 A 31-year-old male presented with a palpable mass in the right parotid area of 5 years duration. The mass was slowly growing and he felt facial numbness on the right side of his face. Physical examination showed evidence of a mass 4 cm in diameter, which was round, fixed, and nontender during palpation. His facial expression was symmetrically intact. Magnetic resonance imaging (MRI) showed a 3 ⫻ 4 cm well-enhanced round mass in the right parotid area. The mass was removed together with the attached facial nerve, and the nerve was repaired with end-to-end anastomosis using the greater auricular nerve (Figure 1). Facial expression was normal and symmetric preoperatively (Grade I). Immediate postoperative facial function was grade VI and
MRI and intraoperative findings in Case 1. (A) An MRI showing a 3 ⫻ 4 cm well-enhanced round mass in the right parotid area (arrowheads). (B) A large mass originating from the facial nerve trunk (arrow). The mass was removed together with the attached facial nerve and the nerve was repaired with end-to-end anastomosis using the greater auricular nerve.
1
facial function improved gradually to Grade III over 9 months. There was no further improvement of facial function during the 6-year follow-up period. CASE 2 A 43-year-female presented with a right infraauricular mass and facial paralysis that she had experienced for 2 years. She also complained of hearing loss and intermittent otorrhea. The infra-auricular mass was 3 ⫻ 4 cm in size and multilobular, nontender, firm, and rather fixed. The tympanic membrane showed retraction of the whole membrane and keratin debris had drained from the attic. Pathologically, schwannoma was suggested by a preoperative fine needle aspiration biopsy. A temporal bone MRI showed a mass involving the entire mastoid cavity and infratemporal fossa. Coincidentally, cholesteatoma involving the
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upper respiratory infection (URI) symptoms, and hearing loss and vertigo suddenly developed, followed by facial palsy. Physical examination showed an intact tympanic membrane and facial palsy of House-Brackmann Grade IV. Audiometry showed profound sensorineural hearing loss, and vestibular function was decreased in his left ear. MRI showed a small, 1 ⫻ 2 cm, well-enhanced mass in the left internal auditory canal (Figure 3). The translabyrinthine approach was performed. The mass originated in the internal auditory canal of the facial nerve. The mass was removed together with the attached facial nerve, and the nerve was repaired by a cable graft between the intracranial and mastoid portions using the greater auricular nerve. Facial function was Grade VI immediately postoperatively and improved to Grade III over a 1-year follow-up. There was no further improvement in facial function until 4.5 years after the removal of the mass.
Results External appearance and intraoperative finding in Case 2. (A) A 4 ⫻ 5 cm large infra-auricular mass (arrowheads). (B) A large mass occupying the whole mastoid cavity and extending into the infratemporal fossa (arrows). There was no part of the facial nerve that was healthy. SS: sigmoid sinus, SCM: sternocleidomastoid muscle.
2
attic area was also noticed. The mass was completely removed using the infratemporal fossa approach. Intra-operative findings showed a large mass occupying the whole mastoid cavity with the mass extended and attached to the sigmoid sinus and jugular foramen. The facial nerve was not healthy throughout its entire course from the geniculate ganglion to the peripheral branches (Figure 2). Facial function was Grade VI preoperatively and immediately postoperatively. Before the operation pure tone average was 27 dB in air conduction and became 53 dB after the operation. Bone conduction was normal and did not change postoperatively. After a 5-year follow-up, facial expression had not changed significantly, but the upper eyelid moved a little, enough to cover the eyeball with maximal effort. CASE 3 A 21-year-old male presented with left side facial palsy of 20 days’ duration. He had previously had
The initial presenting symptom was facial nerve paralysis in 4 out of 8 tumors. One patient showed recurrent facial paralysis with some recovery. Seven out of 8 patients showed facial nerve paralysis during the course of the disease (Table 1). Facial nerve paralysis was most severe in intratemporal tumors and less severe in parotid tumors. Patients with IAC initially suffered from hearing loss and intermittent vertigo and showed decreased vestibular function. Patients with intratemporal tumors also complained of hearing loss. In 1 patient who did not experience facial paralysis, facial numbness was the only symptom until a parotid mass was found during a physical examination. Two patients with IAC masses also complained of sensorineural hearing loss with tinnitus, and they consulted a doctor earlier than the others because of the sudden onset of multiple symptoms. Three patients with intratemporal masses (including a case of an intra- and extratemporal mass) complained of conductive hearing loss with low-tone tinnitus. Tumors were completely removed by superficial parotidectomy in parotid tumors, the translabyrinthine approach in 1 IAC tumor, the middle fossa approach in the other IAC tumor, the transmastoid approach in mastoid tumors, and the infratemporal fossa approach in intratemporal and extratemporal tumors. There were no severe postoperative complications (Table 2). Facial nerves were sacrificed in 6 cases. Facialhypoglossal crossover technique was performed in
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MRI, intraoperative, and pathologic findings in Case 3. (A, B) Axial and coronal MRI showing a small 1 ⫻ 2 cm, well-enhanced mass in the left internal auditory canal (arrows). (C) Mass (*) originating from the facial nerve (arrow) in the internal auditory canal. The mass was removed together with the attached facial nerve and the nerve was repaired by a cable graft between the intracranial portion and mastoid portion (mFN) using the greater auricular nerve. (D) Pathologic finding (⫻200) showing a palisading array of nuclei around a central mass of cytoplasm (Verocay body, arrows). This finding was an Antoni A type.
3
2 cases of intratemporal schwannoma, and end-toend cable grafts using the greater auricular nerve were performed in 1 of each parotid and IAC schwannoma. End-to-end anastomosis with the sural nerve was applied in 1 case of intratemporal mass. In this case, the labyrinthine and meatal portion of the facial nerve were also involved, and the translabyrinthine approach was performed. The cable graft was performed between the IAC and facial nerve trunk in the parotid gland. In 1 patient, the mass involved all the peripheral branches, and facial reanimation surgery is planned. Facial nerves were able to be preserved after resection of the mass in 1 of the parotid cases and 1 IAC case. Facial expression improved in patients who received the facial nerve graft except for one case with an intact facial function at presentation. In the
cases of facial nerve preservation, facial function did not change postoperatively. The final facial expression was Grade III in the cases with the cable graft (GAN and sural nerve) and Grade IV in the cases with facial-hypoglossal cross-over (Table 2). MRIs were checked in all the patients except the last case at one year of follow-up, and there was no evidence of recurrence. Up to the last follow-up, there have been no specific symptoms or signs suggesting recurrence of the tumor.
Discussion Facial palsy is induced by various causes, with 50⬃80% of cases thought to be idiopathic [1]. Since Schmidt first reported a case of facial nerve
IV ⫹ (2 mos) ⫹ facial palsy hearing loss
2 mos
⫹
⫺
V ⫹ (7 yrs) ⫹ hearing loss, tinnitus
L 48 8
F
60 7
F
L
Internal auditory canal (IAC) Intratemporal (labyrinthine portion-stylomastoid foramen) Intratemporal (geniculate ganglion-stylomastoid foramen) Intra- & Extratemporal (IACfacial nerve trunk) R R 31 51 5 6
F F
L 21 4
M
10 yrs
⫹
⫺
III V ⫹ ⫹ ⫹ ⫹ 1 mo 8 yrs
⫹ ⫹
⫹ ⫹
IV ⫹ (1 mo) ⫹
hearing loss, vertigo facial palsy recurrent facial palsy
2 mos
⫹
⫹
I IV VI ⫺ ⫹ ⫹ (2 yrs) ⫺ ⫺ ⫺ ⫺ ⫺ ⫹ facial numbness facial palsy infra-auricular mass
Intraparotid Intraparotid Intra- & Extra-temporal (geniculate ganglion-distal branches) Internal auditory canal (IAC) R L R 31 47 43 1 2 3
M F F
SYMPTOM
INITIAL OF MASS
EXTENT SIDE AGE (YRS)
SEX
1 yr 2 yrs 2 yrs
TINNITUS LOSS
⫺ ⫺ ⫺
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NO
1
Demographic Data and Presentation of Facial Nerve Schwannoma Cases
DURATION
HEARING
ASSOCIATED
VERTIGO
SYMPTOMS
FACIAL PARALYSIS
FACIAL EXPRESSION
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schwannoma, many authors reported a 0.15 to 0.8% prevalence of facial nerve schwannoma [13]. For a diagnosis of facial nerve schwannoma, one must put together many diagnostic tools, such as clinical aspect and radiologic and pathologic findings. As we discussed above, the clinical manifestations of facial nerve schwannoma vary depending on the site and size of the tumor mass. Facial palsy is a distinctive and relatively common symptom, having an 84% incidence in intratemporal tumors and 34% in extratemporal tumors [13]. But other investigators have reported that hearing loss and tinnitus were the most common symptoms, and facial palsy was found in only 45% of 48 cases [11]. In this study, 7 out of 8 cases (86%) had facial palsy of varying degree and hearing loss was found in 5 cases (71%). As for initial symptoms, only 4 out of 8 patients experienced facial paralysis. Another 4 patients initially suffered from hearing loss, vertigo, facial numbness, or facial mass. When the site of the lesion was categorized as intratemporal (including IAC) and extratemporal, we found few symptoms in extratemporal cases, but more than 3 symptoms, such as hearing loss, tinnitus, dizziness, and facial weakness or pain, in intratemporal cases. Based on this finding, intratemporal schwannoma showed more severe clinical manifestations. Recently, the development and improvement of radiologic technique, such as gadolinium-enhanced MRI, has made it possible to diagnose small facial nerve schwannomas earlier. MRI can differentiate facial nerve schwannoma from hemangioma, cholesterol granuloma, and meningioma [2,11]. In our series, all the facial nerve schwannomas were diagnosed with the help of a preoperative MRI scan and confirmed by pathologic examination. MRI was more helpful in facial nerve schwannomas within the IAC or mastoid cavity. Inside the IAC, facial nerve schwannoma could be differentiated from vestibular schwannoma by posterior displacement of the tumor relative to the IAC in MRI [5,11,15,16]. Other authors, however, have insisted that MRI could not reveal facial nerve tumors [8]. In our series, there were 2 cases of a tumor originating inside the IAC. MRI could not differentiate this mass from vestibular schwannoma because of a lack of evidence of posterior displacement. In the cases of vestibular schwannoma, only 3.2% of the patients were reported to have facial weakness at presentation [18], and the incidence of facial paralysis was greater for the larger tumors. On the contrary, facial nerve symptoms were more frequently observed (up to 73%) in the patients with facial nerve schwannoma at initial presentation
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2
Intra-Operative Findings and Follow-up Data
COMPLICATIONS OPERATIVE
FACIAL
NO
APPROACH
1
Superficaial parotidectomy Superficaial parotidectomy Infratemporal fossa approach
4 ⫻ 4 ⫻ 3 cm
Translabyrinthine approach Middle fossa approach Middle fossa and transmastoid approach Transmastoid approach Translabyrinthine approach
1 ⫻ 2 ⫻ 1 cm
2 3 4 5 6 7 8
MASS
SIZE
NERVE MANAGEMENT
FACIAL
NERVE GRAFT
IMMEDIATE
LATE
FACIAL
EXPRESSION
AT PRESENTATION
LAST
F/U
F/U
DURATION
Excision and anastomosis not sacrificed
End to end anastomosis with GAN graft –
–
–
I
III
6 yrs 6 mos
–
–
IV
IV
2 yrs 6 mos
Excision and no anastomosis Excision and anastomosis not sacrificed
–
wound dehiscence
–
VI
VI
5 yrs
End to end anastomosis with GAN graft –
keloid
keloid
IV
III
4 yrs 6 mos
–
–
III
III
4 yrs 4 mos
N/A**
Excision and anastomosis
VII–XII anastomosis
–
Tinnel sign
V
IV
6 mos
N/A**
Excision and anastomosis Excision and anastomosis
VII–XII anastomosis
–
–
V
IV
2 yrs
End to end anastomosis with sural nerve graft
–
–
IV
III
10 mos
2 ⫻ 2 ⫻ 2 cm 3 ⫻ 4 ⫻ 3 cm*
2 ⫻ 2 ⫻ 1 cm
3 ⫻ 3 ⫻ 2 cm
*Size of extratemporal mass, whole mastoid cavity was also filled with the mass. **Mass occupying whole mastoid cavity.
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Facial Nerve Schwannoma
[4,9,11], such as sudden or gradual onset of facial paralysis and recurrent paralysis as shown in our cases. The patients who had a tumor originating inside the IAC in this study complained of hearing loss, vertigo, and facial palsy, which are indistinguishable from the symptoms of vestibular schwannoma. However, they experienced the early onset of facial palsy, and an electro-diagnostic test at 1 and 2 months after the onset of symptoms showed that more than 95% of the facial nerve had degenerated. Taken together, early onset of facial weakness is a suspicious sign of facial nerve schwannoma in the case of a tumor inside the IAC, and a high index of suspicion is needed to precisely diagnose facial nerve schwannoma. The aim of surgery in facial nerve schwannoma is complete tumor excision with preservation of the facial and hearing functions [11]. Therefore, it is very important to decide upon the location and size of the tumor, facial nerve function, and hearing before choosing the treatment method. We performed different surgical approaches in line with the location, size, and grade of invasion of the tumor. Theoretically, facial function could be preserved when the mass is removed with the facial nerve sheath without interrupting the nerve fibers [14]. We were able to preserve the facial nerve in 2 cases, but inevitably the facial nerve was sacrificed in the rest of the cases. Facial function gradually improved in cases with facial nerve grafts. The final grade of facial expression in patients with end-to-end facial nerve anastomsis with cable graft was grade III. In the cases of facial nerve preservation, there was no improvement of facial function. In other investigators’ series, when the facial nerve could be preserved, as, for example when a mass was located eccentrically on the nerve, 1 of 2 cases completely recovered facial function [15]. From these findings, we suggest that resection and anastomosis of the facial nerve is to be encouraged when facial function is worse than Grade III and graft materials are available. Also, end-to-end anastomosis is better than facialhypoglossal cross-over wherever possible. In the point of the postoperative facial function, the size of the mass could be a factor for the prediction of the function. Three cases in which the end-to-end cable graft was possible had smaller tumors than the other cases. From above, early surgical intervention was highly recommended. Hearing function could be preserved in all cases that had serviceable preoperative hearing. Three out of 8 cases had profound hearing loss, and the
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labyrinth was resected for the complete removal of the mass. There has been a lot of debate about the timing of surgical intervention for facial nerve schwannoma. Many authors have insisted that it is beneficial to operate as early as possible except in cases of poor general status or advanced age [11]. We also believe early surgical intervention and careful facial nerve anastomosis to be the best management of facial nerve schwannoma.
Conclusion Facial nerve schwannomas can present in various ways. Depending on the site of origin and presenting symptoms and signs, we were able to diagnose facial nerve schwannoma preoperatively. According to the operative management of the facial nerve, we could estimate the postoperative outcome of facial function. Our finding could be pivotal in the management of the facial nerve schwannoma. REFERENCES 1. Bleicher JN, Hamiel S, Gengler JS. A survey of facial paralysis: etiology and incidence. Ear Nose Throat J 1996;75:355–7. 2. Chen JM, Moll C, Wichmann W, Kurrer MO, Fisch U. Magnetic resonance imaging and intraoperative frozen sections in intratemporal facial nerve schwannomas. Am J Otol 1995;16:68 –74. 3. Chun YM, Park K, Lee JS, Chun SH. The management of facial nerve schwannoma. Kor J Otolaryngol 1997; 40:1052–7. 4. Dort JC, Fisch U. Facial nerve schwannomas. Skull Base Surg 1991;1:51–6. 5. Fagon PA, Misra SN, Doust B. Facial neuroma of the cerebellopontine angle and the internal auditory canal. Laryngoscope 1993;103:442–6. 6. House JW, Brackmann DE. Facial nerve grading system. Otolaryngol Head Neck Surg 1985;93:146 –7. 7. Kim CS, Sung MH, Hwang EG, Chung HW, Han MH. Surgical management of intratemporal facial nerve neurilemmoma. Kor J Otolaryngol 1989;32:391–408. 8. Lassaletta L, Roda JM, Frutos R, Patron M, Gavilan J. Facial nerve schwannoma of the cerebellopontine angle: a diagnostic challenge. Skull Base 2002;12:203–7. 9. Lipkin AF, Coker NJ, Jenkins HA, Alford BR. Intracranial and intratemporal facial neuroma. Otolaryngol Head Neck Surg 1987;96:71–9. 10. Nager GT. Pathology of the ear and temporal bone. Baltimore: Williams & Wilkins, 1993;597–9. 11. O’Donoghue GM, Brackmann DE, House JW, Jackler RK. Neuromas of the facial nerve. Am J Otolaryngol 1989;10:49 –54. 12. Pulec JL. Facial nerve neuroma. Ear Nose Throat J 1994;73:721–52. 13. Saito H, Baxter A. Undiagnosed intratemporal facial nerve neurilemmomas. Arch Otolaryngol 1972;95: 415–9. 14. Sataloff RT, Frattali MA, Myers DL. Intracranial facial
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neuromas: total tumor removal with facial nerve preservation: a new surgical technique. Ear Nose Throat J 1995;74:244 –56. Sherman JD, Dagnew E, Pensak ML, van Loveren HR, Tew JM. Facial nerve neuromas: report of 10 cases and review of the literature. Neurosurg 2002;50: 450 –6. Symon L, Cheesman AD, Kawauchi M, Bordi L. Neuromas of the facial nerve: a report of 12 cases. Br J Neurosurg 1993;7:13–22. Walter JB, Israel MS. Structure and effects of some common tumors. In: General pathology, 5th ed. Edinburgh: Churchill Livingstone, 1979;219 –20. Wiegand DA, Ojemann RG, Fickel V. Surgical treatment of acoustic neuroma (vestibular schwannoma) in the United States: report from the Acoustic Neuroma Registry. Laryngoscope 1996;106:58 –66. Yamaki T, Morimoto S, Ohtaki M, et al. Intracranial facial nerve neuroma: surgical stratage of tumor removal and functional reconstruction. Surg Neurol 1998;49:538 –46.
COMMENTARY
The authors report on 8 facial nerve schwannomas treated from 1993 through 2001. Nerve reconstruction was performed in 5 of 8 patients. The images
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are of excellent quality, and the presented cases demonstrate the high variability in facial nerve schwannomas. Early surgical intervention in large tumors with facial nerve paresis of varying degrees, as in the series presented, is clearly indicated. Still, in this series one presentation of facial nerve schwannoma is missing: very small tumors, diagnosed with mild symptoms and without facial nerve paresis. When treating this patient group, the neurosurgeon faces difficult decisions. Early surgical intervention and careful nerve anastomosis might, in this patient group, not always be the best solution out of the physicians dilemma. The patients’ expectations, profession and particular situation have to be carefully analyzed before deciding about treatment options in this selected group of tumors. Wolf Lu ¨ demann, M.D., Madjid Samii, M.D. Ph.D. International Neuroscience Institute Hannover, Germany