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Trochlear Schwannoma Arising from Transition Zone of Nerve Sheath in the Pineal Region: Case Report and Review of the Literature
Journal Pre-proof Trochlear schwannoma arising from transition zone of nerve sheath in the pineal region: Case report and review of the literature Yu-Hsiang Lan, MD, Ying-Ching Li, MD, Cheng-Nen Chang, MD, PhD, Bo Zhang, MD, Yu-Jen Lu., MD, PhD PII:
S1878-8750(20)30284-9
DOI:
https://doi.org/10.1016/j.wneu.2020.02.019
Reference:
WNEU 14294
To appear in:
World Neurosurgery
Received Date: 17 January 2020 Accepted Date: 3 February 2020
Please cite this article as: Lan Y-H, Li Y-C, Chang C-N, Zhang B, Lu. Y-J, Trochlear schwannoma arising from transition zone of nerve sheath in the pineal region: Case report and review of the literature, World Neurosurgery (2020), doi: https://doi.org/10.1016/j.wneu.2020.02.019. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Inc.
Trochlear schwannoma arising from transition zone of nerve sheath in the pineal region: Case report and review of the literature Yu-Hsiang Lan*, MD1; Ying-Ching Li*, MD2; Cheng-Nen Chang, MD, PhD1,2 ; Bo Zhang, MD3; Yu-Jen Lu. MD, PhD2 1
School of medicine, Chang Gung University, Address: No.259, Wenhua 1 st Rd.,
Taoyuan, 333, Taiwan 2
Department of Neurosurgery, Chang Gung Memorial Hospital, Linkou Medical
Center, Address: No.5, Fusing St., Taoyuan, 333, Taiwan 3
Department of Neurosurgery, Chang Gung Memorial Hospital, Xiamen, Address: No.
123 Xiafei Road, Haicang District, Xiamen, Fujian *These authors contributed equally to this work.
Corresponding author: Yu-Jen Lu, MD, PhD Department of Neurosurgery, Chang Gung Memorial Hospital, Linkou Medical Center, Address: No.5, Fusing St., Taoyuan, 333, Taiwan Tel: +886-3-3281200 ext. 2119 Fax: +886-3-3285818 Email: [email protected]
Keywords: Pineal region, Schwannoma, Transition zone, Trochlear nerve Running title: Trochlear schwannoma at pineal region Source of Funding: None Conflict of Interest: The authors have no proprietary or commercial interest in any materials discussed in this article.
Abstract Background: This report presents the third case of trochlear schwannoma arising from the pineal region and the first to be resected using a paramedian infratentorial supracerebellar approach. Schwannomas of cranial nerves has traditionally been thought to arise from the transitional point where the axonal envelopment switches from glial cells to Schwann cells, although recent temporal bone histopathologic evidence from vestibular schwannomas challenges this view. Of the 38 cases of pathology-confirmed trochlear schwannoma in the literature, there are only 2 cases arising from the pineal region, where the nerve sheath transition zone is located. Here, we discuss an unusual case of trochlear schwannoma arising from this transition zone. Case Description: A 65-year-old male was admitted to our institute following a traffic accident. He complained of headache and dizziness, and a CT scan revealed an isodense mass in the pineal region with obstructive hydrocephalus. MRI with contrast showed a enhancing mass in the pineal region. The tumor was subtotally resected using a paramedian infratentorial supracerebellar approach, and pathology confirmed the diagnosis of trochlear schwannoma. Conclusions: Trochlear schwannoma should be considered when a mass is identified in the pineal region. This diagnosis should still be entertained for mass lesions along the free tentorial edge because the tumor may arise distant from the glial-Schwann transition zone located by the dorsal midbrain. We propose a treatment algorithm for this rare 1
tumor that seeks to maximize functional outcome.
2
Introduction Schwannomas are benign tumors of the nerve sheath that arise from Schwann cells. These tumors account for 8% of all primary brain tumors.1 Intracranially, schwannomas show a predilection for the sensory cranial nerve, and seldom arise from the motor cranial nerve.2 The vestibular nerve is the most common nerve of origin, accounting for 80~90% of all cases, followed by the trigeminal, glossopharyngeal, vagal, facial, accessory, hypoglossal, oculomotor, trochlear, and abducens nerves.3, 4 Schwannomas arising from the trochlear nerve are very rare, especially in non-neurofibromatosis patients.5 Only 38 pathology-confirmed cases of trochlear schwannomas have been reported in the literature to date (Table 1).1, 2, 4-37 Herein, we present the third case report of trochlear schwannoma arising from the pineal region and the first to be resected using a paramedian infratentorial supracerebellar approach.
Clinical Presentation A 65-year-old male with hypertension under medication control and no comorbidities such as neurofibromatosis was admitted to our institute following a traffic accident. At presentation, he complained of headache and dizziness. Neurologic examination showed no significant cranial nerve dysfunction, and eye movements were intact without limitation. Laboratory data including tumor markers (α-fetoprotein and β-hCG) were all within normal levels. Computed tomography revealed an isodense mass in the pineal region with cerebral aqueduct compression, leading to obstructive hydrocephalus. MRI with contrast revealed a well-demarcated 3
enhancing mass in the pineal region (Fig. 1A-C), and an angiogram revealed tumor blush in the pineal region with arterial supply from the posterior medial choroidal artery (Fig. 2A-B). Due to the presence of a large tumor in the pineal region with obstructive hydrocephalus, cytoreduction microsurgery was indicated. The tumor was subtotally removed using a paramedian infratentorial supracerebellar approach. Intraoperative finding was confirmatory intra-operative of a tumor arising from the trochlear nerve. Pathologic examination revealed that the neoplasm consisted of spindle-shaped cells arranged in a palisading pattern, forming areas of Antoni A and Antoni B (Fig. 3A-B). Hyalinized and thrombosed vessels were also noted (Fig. 3C). Furthermore, immunohistochemical examination revealed diffuse expression of S-100 protein, which confirmed the diagnosis of schwannoma (Fig. 3D). A repeat MRI of the brain 4 months after surgery showed no evidence of rapid regrowth (Fig. 4A-C). The patient gave consent for images and other clinical information to be reported in the medical publication.
Discussion Trochlear schwannomas may be classified into three categories: cisternal, cisternocavernous and cavernous.15 They commonly originate from the cisternal part of the nerve, lateral or anterolateral to the midbrain in the region of the ambient cistern, and just beneath the tentorium edge,1 and may extend medially to the prepontine cistern and interpeduncular cistern, or upwards to the tentorial incisura.5 Larger tumors may compress the adjacent cranial nerves and the brainstem, causing a number of extra-trochlear neurological symptoms (Table 2). Diplopia (63%) is the 4
most common, while others include headache (45%), hemiparesis (39%), ataxia (32%), trigeminal nerve dysfunction (30%), facial palsy (18%), hemiparesthesia (16%), hearing loss (8%) and tinnitus (3%). It is worth noting that trochlear nerve palsy was found in only 50% of cases at presentation. This could be explained by the trochlear nerve fibers being displaced and twisted owing to the length of this segment, instead of being destroyed by the large tumor.23 Most neoplasms of the pineal region fall into one of three histological groups: germ cell tumors, pineal parenchymal tumors and gliomas. In a series of 633 cases from the SEER database, these groups accounted for 59%, 30% and 5% of patients, respectively.38 Other pineal region masses include meningiomas, pineal cysts, vascular malformations, and metastatic tumors. In our case, an enhancing mass adjacent to the tentorium or a cranial nerve is highly suggestive of meningioma or schwannoma. An angiogram revealed that the tumor was supplied by the posterior medial choriodal artery, which is the posterior branch of the posterior cerebral artery. Hence, pineal meningioma, which is usually supplied by the tentorial branch of the meningohypophyseal trunk or the meningeal branch of the external carotid artery,39-41 was less likely. A definitive diagnosis is made based on intraoperative findings and pathologic examination. Schwannomas of cranial nerves is commonly thought to arise from the transitional point where the axonal envelope switches from glial cells to Schwann cells.1 Accordingly, the most common intracranial schwannoma, vestibular schwannoma, is believed to originate near the site of the central myelin–peripheral myelin transition zone within the internal auditory canal.15, 42 However, a more recent 5
temporal bone histopathologic evidence challenges this view sharply,43 contending that the transition zone theory is without credible evidence and tumors arise from Schwann cells anywhere from the glial-Schwann junction up until the nerve terminations to end organs. The origination of this trochlear schwannoma located in the pineal region may be attributed to the glial-Schwann transition zone. Anatomically, the transition zone of trochlear nerve sheath is only 0.6 mm away from its exit from the dorsal midbrain,1 located in the quadrigeminal cistern. Interestingly, of the 38 previously reported cases, the vast majority of 36 cases (95%) originated from the anterior/lateral peri-mesencephalic cisterns or the cavernous sinus. Only 2 cases (5%) arose from the pineal region,34, 37 where the transition zone is located. The percentages of each type of previously published trochlear schwannomas are shown in Fig.5 and we separate the transition zone (quadrigemnial cistern) from the cisternal group to demonstrate this distinction. It appears the majority of trochlear schwannomas arise away from the transition zone. As with other cranial nerve schwannomas, the gold-standard treatment of trochlear schwannoma consists of surgical resection with preservation of the nerve if possible. Two previously-reported cases of trochlear schwannoma in the pineal region were resected using the paraoccipital transtentorial approach and the transventricular transvelar approach, respectively.34, 37 In our case, the tumor was resected using the paramedian infratentorial supracerebellar approach, which is a variation of supracerebellar craniotomy. The paramedian infratentorial supracerebellar approach
6
was performed to facilitate direct access to the tumor, and to reduce risk to deep venous structures and the cerebellum, and spared the vermian veins.44, 45 Due to the rarity of trochlear schwannoma, management guidelines are not yet available. Hence, we aimed to propose a rational treatment algorithm based on case series46, 47 review and discuss management and clinical outcomes of trochlear schwannomas (Fig. 6). All patients with a tumor that exerts a significant mass effect, including brain stem compression, cranial nerve palsy, long tract sign, or increased intracranial pressure, should undergo cytoreduction surgery, if there are no contraindications.46 Planned subtotal resection with early or on-demand postoperative radiosurgery may be an option to achieve better functional preservation of the trochlear nerve.46, 48, 49 The rationale for this approach is that a growing trochlear schwannoma enlarges very slowly, with an estimated average of 0.19 mm/year, compared to 1.2 mm/year for vestibular schwannoma.47, 50 Hence, patients with symptoms of diplopia only or asymptomatic patients have an excellent prognosis, and no neurosurgical intervention is needed immediately.47 If the tumor does not increase in size in the first year, which is predictive of future growth,51 regular follow-up and observation are recommended. If the tumor size increases in the first year, radiosurgery or debulking surgery may be considered, depending on the tumor size. A rapid tumor growth rate (>4 mm/year) is associated with a cystic component and hemorrhage in the tumor.51
Conclusion Trochlear schwannoma should be considered when a mass is identified in the 7
pineal region. This diagnosis should still be entertained for mass lesions along the free tentorial edge because the tumor may arise distant from the glial-Schwann transition zone located by the dorsal midbrain. We propose a treatment algorithm for this rare tumor that seeks to maximize functional outcome.
Acknowledgement No funding was provided for the research in this study.
8
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40. Inoue A, Ohnishi T, Kohno S, Ohtsuka Y, Nakamura Y, Mizuno Y, et al. Two cases of pineal-region meningiomas derived from arachnoid membrane over the vein of Galen without dural attachment. World J Surg Oncol. 2015;13:226. 41. Nowak A, Dziedzic T, Czernicki T, Kunert P, Marchel A. Falcotentorial and velum interpositum meningiomas: two distinct entities of the pineal region. Neurol Neurochir Pol. 2014;48:397-402. 42. St Martin MB, Hirsch BE. Imaging of hearing loss. Otolaryngol Clin North Am. 2008;41:157-178. 43. Roosli C, Linthicum FH Jr, Cureoglu S, Merchant SN. What is the site of origin of cochleovestibular schwannomas? Audiol Neurootol. 2012;17(2):121-5. 44. Kulwin C, Matsushima K, Malekpour M, Cohen-Gadol AA. Lateral supracerebellar infratentorial approach for microsurgical resection of large midline pineal region tumors: techniques to expand the operative corridor. J Neurosurg. 2016;124:269-276. 45. La Pira B, Sorenson T, Quillis-Quesada V, Lanzino G. The paramedian supracerebellar infratentorial approach. Acta Neurochir (Wien). 2017;159:1529-1532 46. Torun N, Laviv Y, Jazi KK, Mahadevan A, Bhadelia RA, Matthew A, et al. Schwannoma of the trochlear nerve—an illustrated case series and a systematic review of management. Neurosurg Rev. 2016;41:699-711. 47. Yoshimoto Y. Systematic review of the natural history of vestibular schwannoma. J Neurosurg. 2005;103:59-63. 48. Kondziolka D, Lunsford LD, McLaughlin MR, Flickinger JC. Long-term outcomes after radiosurgery for acoustic neuromas. N Engl J Med. 1998;339:1426– 13
1433. 49. Lunsford LD, Niranjan A, Flickinger JC, Maitz A, Kondziolka D. Radiosurgery of vestibular schwannomas: summary of experience in 829 cases. J Neurosurg. 2005;102:195–199. 50. Elmalem VI, Younge BR, Biousse V, Leavitt JA, Moster ML, Warner J, et al. Clinical Course and Prognosis of Trochlear Nerve Schwannomas. Ophthalmology. 2009;116:2011-2016. 51. Paldor I, Chen AS, Kaye AH. Growth rate of vestibular schwannoma. J Clin Neurosci. 2016;32:1-8.
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Figure Legends Figure 1. Preoperative T1-weighted contrast enhanced MRI (A-C) reveled a contrast enhancing heterogeneous mass in the pineal region. Figure 2. Angiography showed tumor blush in the pineal region (circle in A, B) with arterial supply from posterior medial choroidal artery (arrow in A, B). Figure 3. Hematoxylin-eosin stain in low magnification (A) and high magnification (B) showed the spindle-shaped cells arranged in palisading pattern and forming areas of Antoni A (black arrow in B) and Antoni B (white arrow in B). Hyalinized and thrombosed vessels were noted (C). Immunopositivity for S-100 protein (D), confirm the diagnosis of schwannoma. Figure 4. Postoperative MRI (A-C) confirmed some residual tumor revealing a subtotal resection. Figure 5. Anatomic pathway of trochlear nerve and the classification of trochlear schwannomas with percentage. Figure 6. A rational treatment algorithm for trochlear schwannomas
15
Table 1. Previously published 38 cases of pathology-confirmed trochlear schwannomas Age / Gender
Citation
King et al.6
55 / F
Presentation Headache, facial and extremity hemiparesthesia, ataxia, vertigo Diplopia, headache, facial paresis, hemianesthesia, hemiparesthesias, ataxia
Boggan et al.7
32 / F
Ho et al.2
58 / F
Leunda et al.8
16 / F
Asymptomatic Diplopia, headache,
Location
Duration of symptoms
Size(cm)
Preoperative IVth palsy
Degree of resection
Follow-up and residual symptoms
cisternal
1 year
3.0 × 4.0
No
Total
18 months: IVth palsy, right extremity paresis
cisternal
2 years
4.0
Yes
Total
8 months : IVth palsy, absent right corneal reflex
cisternal
ND
cisternocavernous
5 months
3.0 × 4.0
No
ND
ND; found at autopsy
4.5
Yes
Total
6 months: IVth palsy
54 / M
Diplopia, headache
cisternal
7 months
3.5
Yes
Total
1 year: IVth palsy
Garen et al.9
18 / F
Diplopia, ptosis
cisternal
6 months
2.5
No
Total
ND: partial IVth palsy
Yamamoto et al.10
37 / F
Diplopia, headache, nausea, vomiting
cisternal
< 1 week
1.0 × 9.0 × 7.0
Yes
Total
5 years: IVth palsy
23/F
Diplopia, left hemiparesis, left. facial numbness, ataxia
cisternal
1 month
1.8 × 1.5
No
Total
ND: IVth palsy
cisternal
13 months
ND
No
Subtotal
cisternal
5 months
2.0
No
Total
2 years: IVth palsy, right extremity spasticity.
cisternal
ND
ND
Yes
Total
ND: IVth palsy
cisternal
12 months
4.0 × 3.0
Yes
Total
5 years: IVth palsy
Leunda et al.
Murakawa.
8
11
Tokuriki et al.12
Maurice-Williams et al.13
Samii et al.
14
Celli et al.15
43 / M
56 / M
53/F
51 / M
Extremity hemiplegia and hemianesthesia, ataxia Diplopia, headache, facial and extremity hemiparesis, dysarthria Right oculomotor nerve palsy, right hemiparesis Diplopia, headache, hemiparesthesia, ataxia
1 month: IVth palsy
Abe et al.16
Abe et al.
57 / M
16
60/M
Jackowski et al.
17
26 / F
Dolenc et al.18
68 / M
Santoreneos et al.
19
35 / F
Beppu et al.20
66 / M
Nadkarni et al.21
48 / F
Shenouda et al.
22
Ture et al.23 Veshchev et al.
Matsui et al.
24
Du et al.25
Shenoy et al.26
5
49 / M
Headache, facial hemianesthesia Left sensory disturbance and hemiparesis Diplopia, headache, tongue hemianesthesia Diplopia, extremity hemiparesis Headache, extremity and facial hemiparesis, ataxia Diplopia, facial hemianesthesia, tinnitus, hearing loss, vertigo Inappropriate laughter Diplopia, headache, dysphagia, ataxia, amnesia
31 / M
Diplopia
26 / F
Atypical facial pain
61 / M
17 / F
54 / F
Diplopia, extremity hemiparesis, dysphagia, ataxia Diplopia, headache, Headache, extremity and facial hemiparesis, dysarthria, dysphagia
4 months: IVth palsy
cisternal
48 months 3.0 × 2.0 × 2.0
No
Total
cisternal
8 months
3.0 × 2.0 × 2.0
No
Total
ND: IVth palsy
cisternal
8 months
ND
Yes
Total
6 months: IVth palsy
cisternal
2 years
3.0 × 2.5 × 2.5
No
Total
cisternal
8 weeks
ND
No
Total
23 months: IVth palsy
cisternal
5 years
2.0 × 2.0 × 1.0
No.
Total
ND: right sixth nerve palsy.
cisternal
6 months
ND
No
Total
6 months: IVth palsy
Cisternocavernous
3 weeks
4.0 × 3.0
Yes
Total
6 years: IVth palsy, left-sided deafness
cisternal
2 months
2.0 × 1.5
Yes
Total
ND: IVth palsy
Cavernous sinus
3 months
ND
No
Total
4 months: IVth palsy
cisternal
3 months
ND
Yes
Total
3 years: IVth palsy
cisternocavernous
3 months
3.8 × 2.9 × 2.5
No
Total
ND: asymptomatic.
cisternal
2 months
ND
No
Total
1 year: left hemianesthesia.
2 months: extremity hemiparesis improved.
Ohba et al.1
42 / M
Diplopia, facial hemianesthesia, extremity and facial hemiparesis, Diplopia, facial hemianesthesia, hearing loss, extremity hemiparesis, ataxia
cisternal
2 weeks
2.5
Yes
Total
4 months: IVth palsy
cisternal
10 months
2.5
Yes
Total
28 months: IVth palsy, right face hypesthesia.
Gerganov et al.27
52 / F
Kohama et al.28
47 / F
Extremity hemiparesis, ataxia
cisternal
5 months
ND
No
Total
ND: IVth palsy
Bartalena et al.29
50 / F
Diplopia
cisternal
3 months
2.5
Yes
Total
15 months: IVth palsy
Younes et al.4
65 / F
cisternal
ND
1.7
Yes
Subtotal
2 years: asymptomatic.
cisternal
10 days
2.7 x 2.7 x 3.0
Yes
Subtotal
1 year: asymptomatic.
cisternal
2 months
0.9 x 0.7 x 1.1
Yes
Total
cisternal
1 month
ND
Yes
Subtotal
cisternal
8 months
ND
No
Total
ND: IVth palsy
cisternal
11 days
2.4 x 2.2 x 3.1
No
Total
6 months: IVth palsy, Parinaud syndrome
cisternal
4 months
ND
Yes
Total
2 years: asymptomatic.
cisternal
6 months
1.7 x 0.9 x 0.8
No
Total
3 months: asymptomatic
cisternal
2 months
2
Yes
Total
12years: asymptomatic
Hatae et al.30 Boucher et al.
Inoue et al.
31
32
44 / M
Diplopia, vertigo, extremity hemiparesis Singultus
64 / M
Diplopia, headache
52 / M
Samadian et al.33
63/M
Chaudhry et al.34
24 / F
Liu et al.35
65/M
Nesvick et al.36
50/M
Farrokhi et al.37
12/M
ND, not described
Diplopia, extremity hemianethesia and hemiparesis, ataxia Diplopia, headache
Headache Diplopia, facial pain Left trigeminal neuralgia Diplopia, headache, ataxia
1 month: IVth palsy
6 months: improved diplopia.
Table 2. Literature review of 38 pathology-confirmed cases of trochlear schwannomas Presenting symptoms Diplopia Headache
24 (63%) 17 (45%)
Long tract sign (motor) Long tract sign (sensory) Ataxia Cranial nerve sign
15 (39%) 6 (16%) 12 (32%)
3rd cranial nerve disorder 4th cranial nerve disorder 5th cranial nerve disorder 6th cranial nerve disorder
9 (24%) 19 (50%) 11 (29%) 0 (0%)
7th cranial nerve disorder 8th cranial nerve disorder Hearing loss
7 (18%) 3 (8%) 3 (8%)
Tinnitus Lower cranial nerve disorder Dysphagia Dysarthria
1 (3%) 4 (11%) 3 (8%) 2 (5%)
Highlights: • This is the third case of trochlear schwannoma arising from pineal region, and the first case to be resected using a paramedian infratentorial supracerebellar approach. • A literature review of all previously reported cases of trochlear schwannoma indicated that trochlear nerve palsy was present initially in only 50% of cases. • The possibility of trochlear schwannoma should be considered when a mass is identified in the pineal region or along the free tentorial edge. • A rational treatment algorithm for trochlear schwannoma that seeks to maximize functional outcome is illustrated in this article.
Abbreviations: CT: Computed tomography MRI: Magnetic resonance imaging
Declaration of Interest: None
S1878-8750(20)30284-9
DOI:
https://doi.org/10.1016/j.wneu.2020.02.019
Reference:
WNEU 14294
To appear in:
World Neurosurgery
Received Date: 17 January 2020 Accepted Date: 3 February 2020
Please cite this article as: Lan Y-H, Li Y-C, Chang C-N, Zhang B, Lu. Y-J, Trochlear schwannoma arising from transition zone of nerve sheath in the pineal region: Case report and review of the literature, World Neurosurgery (2020), doi: https://doi.org/10.1016/j.wneu.2020.02.019. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Inc.
Trochlear schwannoma arising from transition zone of nerve sheath in the pineal region: Case report and review of the literature Yu-Hsiang Lan*, MD1; Ying-Ching Li*, MD2; Cheng-Nen Chang, MD, PhD1,2 ; Bo Zhang, MD3; Yu-Jen Lu. MD, PhD2 1
School of medicine, Chang Gung University, Address: No.259, Wenhua 1 st Rd.,
Taoyuan, 333, Taiwan 2
Department of Neurosurgery, Chang Gung Memorial Hospital, Linkou Medical
Center, Address: No.5, Fusing St., Taoyuan, 333, Taiwan 3
Department of Neurosurgery, Chang Gung Memorial Hospital, Xiamen, Address: No.
123 Xiafei Road, Haicang District, Xiamen, Fujian *These authors contributed equally to this work.
Corresponding author: Yu-Jen Lu, MD, PhD Department of Neurosurgery, Chang Gung Memorial Hospital, Linkou Medical Center, Address: No.5, Fusing St., Taoyuan, 333, Taiwan Tel: +886-3-3281200 ext. 2119 Fax: +886-3-3285818 Email: [email protected]
Keywords: Pineal region, Schwannoma, Transition zone, Trochlear nerve Running title: Trochlear schwannoma at pineal region Source of Funding: None Conflict of Interest: The authors have no proprietary or commercial interest in any materials discussed in this article.
Abstract Background: This report presents the third case of trochlear schwannoma arising from the pineal region and the first to be resected using a paramedian infratentorial supracerebellar approach. Schwannomas of cranial nerves has traditionally been thought to arise from the transitional point where the axonal envelopment switches from glial cells to Schwann cells, although recent temporal bone histopathologic evidence from vestibular schwannomas challenges this view. Of the 38 cases of pathology-confirmed trochlear schwannoma in the literature, there are only 2 cases arising from the pineal region, where the nerve sheath transition zone is located. Here, we discuss an unusual case of trochlear schwannoma arising from this transition zone. Case Description: A 65-year-old male was admitted to our institute following a traffic accident. He complained of headache and dizziness, and a CT scan revealed an isodense mass in the pineal region with obstructive hydrocephalus. MRI with contrast showed a enhancing mass in the pineal region. The tumor was subtotally resected using a paramedian infratentorial supracerebellar approach, and pathology confirmed the diagnosis of trochlear schwannoma. Conclusions: Trochlear schwannoma should be considered when a mass is identified in the pineal region. This diagnosis should still be entertained for mass lesions along the free tentorial edge because the tumor may arise distant from the glial-Schwann transition zone located by the dorsal midbrain. We propose a treatment algorithm for this rare 1
tumor that seeks to maximize functional outcome.
2
Introduction Schwannomas are benign tumors of the nerve sheath that arise from Schwann cells. These tumors account for 8% of all primary brain tumors.1 Intracranially, schwannomas show a predilection for the sensory cranial nerve, and seldom arise from the motor cranial nerve.2 The vestibular nerve is the most common nerve of origin, accounting for 80~90% of all cases, followed by the trigeminal, glossopharyngeal, vagal, facial, accessory, hypoglossal, oculomotor, trochlear, and abducens nerves.3, 4 Schwannomas arising from the trochlear nerve are very rare, especially in non-neurofibromatosis patients.5 Only 38 pathology-confirmed cases of trochlear schwannomas have been reported in the literature to date (Table 1).1, 2, 4-37 Herein, we present the third case report of trochlear schwannoma arising from the pineal region and the first to be resected using a paramedian infratentorial supracerebellar approach.
Clinical Presentation A 65-year-old male with hypertension under medication control and no comorbidities such as neurofibromatosis was admitted to our institute following a traffic accident. At presentation, he complained of headache and dizziness. Neurologic examination showed no significant cranial nerve dysfunction, and eye movements were intact without limitation. Laboratory data including tumor markers (α-fetoprotein and β-hCG) were all within normal levels. Computed tomography revealed an isodense mass in the pineal region with cerebral aqueduct compression, leading to obstructive hydrocephalus. MRI with contrast revealed a well-demarcated 3
enhancing mass in the pineal region (Fig. 1A-C), and an angiogram revealed tumor blush in the pineal region with arterial supply from the posterior medial choroidal artery (Fig. 2A-B). Due to the presence of a large tumor in the pineal region with obstructive hydrocephalus, cytoreduction microsurgery was indicated. The tumor was subtotally removed using a paramedian infratentorial supracerebellar approach. Intraoperative finding was confirmatory intra-operative of a tumor arising from the trochlear nerve. Pathologic examination revealed that the neoplasm consisted of spindle-shaped cells arranged in a palisading pattern, forming areas of Antoni A and Antoni B (Fig. 3A-B). Hyalinized and thrombosed vessels were also noted (Fig. 3C). Furthermore, immunohistochemical examination revealed diffuse expression of S-100 protein, which confirmed the diagnosis of schwannoma (Fig. 3D). A repeat MRI of the brain 4 months after surgery showed no evidence of rapid regrowth (Fig. 4A-C). The patient gave consent for images and other clinical information to be reported in the medical publication.
Discussion Trochlear schwannomas may be classified into three categories: cisternal, cisternocavernous and cavernous.15 They commonly originate from the cisternal part of the nerve, lateral or anterolateral to the midbrain in the region of the ambient cistern, and just beneath the tentorium edge,1 and may extend medially to the prepontine cistern and interpeduncular cistern, or upwards to the tentorial incisura.5 Larger tumors may compress the adjacent cranial nerves and the brainstem, causing a number of extra-trochlear neurological symptoms (Table 2). Diplopia (63%) is the 4
most common, while others include headache (45%), hemiparesis (39%), ataxia (32%), trigeminal nerve dysfunction (30%), facial palsy (18%), hemiparesthesia (16%), hearing loss (8%) and tinnitus (3%). It is worth noting that trochlear nerve palsy was found in only 50% of cases at presentation. This could be explained by the trochlear nerve fibers being displaced and twisted owing to the length of this segment, instead of being destroyed by the large tumor.23 Most neoplasms of the pineal region fall into one of three histological groups: germ cell tumors, pineal parenchymal tumors and gliomas. In a series of 633 cases from the SEER database, these groups accounted for 59%, 30% and 5% of patients, respectively.38 Other pineal region masses include meningiomas, pineal cysts, vascular malformations, and metastatic tumors. In our case, an enhancing mass adjacent to the tentorium or a cranial nerve is highly suggestive of meningioma or schwannoma. An angiogram revealed that the tumor was supplied by the posterior medial choriodal artery, which is the posterior branch of the posterior cerebral artery. Hence, pineal meningioma, which is usually supplied by the tentorial branch of the meningohypophyseal trunk or the meningeal branch of the external carotid artery,39-41 was less likely. A definitive diagnosis is made based on intraoperative findings and pathologic examination. Schwannomas of cranial nerves is commonly thought to arise from the transitional point where the axonal envelope switches from glial cells to Schwann cells.1 Accordingly, the most common intracranial schwannoma, vestibular schwannoma, is believed to originate near the site of the central myelin–peripheral myelin transition zone within the internal auditory canal.15, 42 However, a more recent 5
temporal bone histopathologic evidence challenges this view sharply,43 contending that the transition zone theory is without credible evidence and tumors arise from Schwann cells anywhere from the glial-Schwann junction up until the nerve terminations to end organs. The origination of this trochlear schwannoma located in the pineal region may be attributed to the glial-Schwann transition zone. Anatomically, the transition zone of trochlear nerve sheath is only 0.6 mm away from its exit from the dorsal midbrain,1 located in the quadrigeminal cistern. Interestingly, of the 38 previously reported cases, the vast majority of 36 cases (95%) originated from the anterior/lateral peri-mesencephalic cisterns or the cavernous sinus. Only 2 cases (5%) arose from the pineal region,34, 37 where the transition zone is located. The percentages of each type of previously published trochlear schwannomas are shown in Fig.5 and we separate the transition zone (quadrigemnial cistern) from the cisternal group to demonstrate this distinction. It appears the majority of trochlear schwannomas arise away from the transition zone. As with other cranial nerve schwannomas, the gold-standard treatment of trochlear schwannoma consists of surgical resection with preservation of the nerve if possible. Two previously-reported cases of trochlear schwannoma in the pineal region were resected using the paraoccipital transtentorial approach and the transventricular transvelar approach, respectively.34, 37 In our case, the tumor was resected using the paramedian infratentorial supracerebellar approach, which is a variation of supracerebellar craniotomy. The paramedian infratentorial supracerebellar approach
6
was performed to facilitate direct access to the tumor, and to reduce risk to deep venous structures and the cerebellum, and spared the vermian veins.44, 45 Due to the rarity of trochlear schwannoma, management guidelines are not yet available. Hence, we aimed to propose a rational treatment algorithm based on case series46, 47 review and discuss management and clinical outcomes of trochlear schwannomas (Fig. 6). All patients with a tumor that exerts a significant mass effect, including brain stem compression, cranial nerve palsy, long tract sign, or increased intracranial pressure, should undergo cytoreduction surgery, if there are no contraindications.46 Planned subtotal resection with early or on-demand postoperative radiosurgery may be an option to achieve better functional preservation of the trochlear nerve.46, 48, 49 The rationale for this approach is that a growing trochlear schwannoma enlarges very slowly, with an estimated average of 0.19 mm/year, compared to 1.2 mm/year for vestibular schwannoma.47, 50 Hence, patients with symptoms of diplopia only or asymptomatic patients have an excellent prognosis, and no neurosurgical intervention is needed immediately.47 If the tumor does not increase in size in the first year, which is predictive of future growth,51 regular follow-up and observation are recommended. If the tumor size increases in the first year, radiosurgery or debulking surgery may be considered, depending on the tumor size. A rapid tumor growth rate (>4 mm/year) is associated with a cystic component and hemorrhage in the tumor.51
Conclusion Trochlear schwannoma should be considered when a mass is identified in the 7
pineal region. This diagnosis should still be entertained for mass lesions along the free tentorial edge because the tumor may arise distant from the glial-Schwann transition zone located by the dorsal midbrain. We propose a treatment algorithm for this rare tumor that seeks to maximize functional outcome.
Acknowledgement No funding was provided for the research in this study.
8
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Figure Legends Figure 1. Preoperative T1-weighted contrast enhanced MRI (A-C) reveled a contrast enhancing heterogeneous mass in the pineal region. Figure 2. Angiography showed tumor blush in the pineal region (circle in A, B) with arterial supply from posterior medial choroidal artery (arrow in A, B). Figure 3. Hematoxylin-eosin stain in low magnification (A) and high magnification (B) showed the spindle-shaped cells arranged in palisading pattern and forming areas of Antoni A (black arrow in B) and Antoni B (white arrow in B). Hyalinized and thrombosed vessels were noted (C). Immunopositivity for S-100 protein (D), confirm the diagnosis of schwannoma. Figure 4. Postoperative MRI (A-C) confirmed some residual tumor revealing a subtotal resection. Figure 5. Anatomic pathway of trochlear nerve and the classification of trochlear schwannomas with percentage. Figure 6. A rational treatment algorithm for trochlear schwannomas
15
Table 1. Previously published 38 cases of pathology-confirmed trochlear schwannomas Age / Gender
Citation
King et al.6
55 / F
Presentation Headache, facial and extremity hemiparesthesia, ataxia, vertigo Diplopia, headache, facial paresis, hemianesthesia, hemiparesthesias, ataxia
Boggan et al.7
32 / F
Ho et al.2
58 / F
Leunda et al.8
16 / F
Asymptomatic Diplopia, headache,
Location
Duration of symptoms
Size(cm)
Preoperative IVth palsy
Degree of resection
Follow-up and residual symptoms
cisternal
1 year
3.0 × 4.0
No
Total
18 months: IVth palsy, right extremity paresis
cisternal
2 years
4.0
Yes
Total
8 months : IVth palsy, absent right corneal reflex
cisternal
ND
cisternocavernous
5 months
3.0 × 4.0
No
ND
ND; found at autopsy
4.5
Yes
Total
6 months: IVth palsy
54 / M
Diplopia, headache
cisternal
7 months
3.5
Yes
Total
1 year: IVth palsy
Garen et al.9
18 / F
Diplopia, ptosis
cisternal
6 months
2.5
No
Total
ND: partial IVth palsy
Yamamoto et al.10
37 / F
Diplopia, headache, nausea, vomiting
cisternal
< 1 week
1.0 × 9.0 × 7.0
Yes
Total
5 years: IVth palsy
23/F
Diplopia, left hemiparesis, left. facial numbness, ataxia
cisternal
1 month
1.8 × 1.5
No
Total
ND: IVth palsy
cisternal
13 months
ND
No
Subtotal
cisternal
5 months
2.0
No
Total
2 years: IVth palsy, right extremity spasticity.
cisternal
ND
ND
Yes
Total
ND: IVth palsy
cisternal
12 months
4.0 × 3.0
Yes
Total
5 years: IVth palsy
Leunda et al.
Murakawa.
8
11
Tokuriki et al.12
Maurice-Williams et al.13
Samii et al.
14
Celli et al.15
43 / M
56 / M
53/F
51 / M
Extremity hemiplegia and hemianesthesia, ataxia Diplopia, headache, facial and extremity hemiparesis, dysarthria Right oculomotor nerve palsy, right hemiparesis Diplopia, headache, hemiparesthesia, ataxia
1 month: IVth palsy
Abe et al.16
Abe et al.
57 / M
16
60/M
Jackowski et al.
17
26 / F
Dolenc et al.18
68 / M
Santoreneos et al.
19
35 / F
Beppu et al.20
66 / M
Nadkarni et al.21
48 / F
Shenouda et al.
22
Ture et al.23 Veshchev et al.
Matsui et al.
24
Du et al.25
Shenoy et al.26
5
49 / M
Headache, facial hemianesthesia Left sensory disturbance and hemiparesis Diplopia, headache, tongue hemianesthesia Diplopia, extremity hemiparesis Headache, extremity and facial hemiparesis, ataxia Diplopia, facial hemianesthesia, tinnitus, hearing loss, vertigo Inappropriate laughter Diplopia, headache, dysphagia, ataxia, amnesia
31 / M
Diplopia
26 / F
Atypical facial pain
61 / M
17 / F
54 / F
Diplopia, extremity hemiparesis, dysphagia, ataxia Diplopia, headache, Headache, extremity and facial hemiparesis, dysarthria, dysphagia
4 months: IVth palsy
cisternal
48 months 3.0 × 2.0 × 2.0
No
Total
cisternal
8 months
3.0 × 2.0 × 2.0
No
Total
ND: IVth palsy
cisternal
8 months
ND
Yes
Total
6 months: IVth palsy
cisternal
2 years
3.0 × 2.5 × 2.5
No
Total
cisternal
8 weeks
ND
No
Total
23 months: IVth palsy
cisternal
5 years
2.0 × 2.0 × 1.0
No.
Total
ND: right sixth nerve palsy.
cisternal
6 months
ND
No
Total
6 months: IVth palsy
Cisternocavernous
3 weeks
4.0 × 3.0
Yes
Total
6 years: IVth palsy, left-sided deafness
cisternal
2 months
2.0 × 1.5
Yes
Total
ND: IVth palsy
Cavernous sinus
3 months
ND
No
Total
4 months: IVth palsy
cisternal
3 months
ND
Yes
Total
3 years: IVth palsy
cisternocavernous
3 months
3.8 × 2.9 × 2.5
No
Total
ND: asymptomatic.
cisternal
2 months
ND
No
Total
1 year: left hemianesthesia.
2 months: extremity hemiparesis improved.
Ohba et al.1
42 / M
Diplopia, facial hemianesthesia, extremity and facial hemiparesis, Diplopia, facial hemianesthesia, hearing loss, extremity hemiparesis, ataxia
cisternal
2 weeks
2.5
Yes
Total
4 months: IVth palsy
cisternal
10 months
2.5
Yes
Total
28 months: IVth palsy, right face hypesthesia.
Gerganov et al.27
52 / F
Kohama et al.28
47 / F
Extremity hemiparesis, ataxia
cisternal
5 months
ND
No
Total
ND: IVth palsy
Bartalena et al.29
50 / F
Diplopia
cisternal
3 months
2.5
Yes
Total
15 months: IVth palsy
Younes et al.4
65 / F
cisternal
ND
1.7
Yes
Subtotal
2 years: asymptomatic.
cisternal
10 days
2.7 x 2.7 x 3.0
Yes
Subtotal
1 year: asymptomatic.
cisternal
2 months
0.9 x 0.7 x 1.1
Yes
Total
cisternal
1 month
ND
Yes
Subtotal
cisternal
8 months
ND
No
Total
ND: IVth palsy
cisternal
11 days
2.4 x 2.2 x 3.1
No
Total
6 months: IVth palsy, Parinaud syndrome
cisternal
4 months
ND
Yes
Total
2 years: asymptomatic.
cisternal
6 months
1.7 x 0.9 x 0.8
No
Total
3 months: asymptomatic
cisternal
2 months
2
Yes
Total
12years: asymptomatic
Hatae et al.30 Boucher et al.
Inoue et al.
31
32
44 / M
Diplopia, vertigo, extremity hemiparesis Singultus
64 / M
Diplopia, headache
52 / M
Samadian et al.33
63/M
Chaudhry et al.34
24 / F
Liu et al.35
65/M
Nesvick et al.36
50/M
Farrokhi et al.37
12/M
ND, not described
Diplopia, extremity hemianethesia and hemiparesis, ataxia Diplopia, headache
Headache Diplopia, facial pain Left trigeminal neuralgia Diplopia, headache, ataxia
1 month: IVth palsy
6 months: improved diplopia.
Table 2. Literature review of 38 pathology-confirmed cases of trochlear schwannomas Presenting symptoms Diplopia Headache
24 (63%) 17 (45%)
Long tract sign (motor) Long tract sign (sensory) Ataxia Cranial nerve sign
15 (39%) 6 (16%) 12 (32%)
3rd cranial nerve disorder 4th cranial nerve disorder 5th cranial nerve disorder 6th cranial nerve disorder
9 (24%) 19 (50%) 11 (29%) 0 (0%)
7th cranial nerve disorder 8th cranial nerve disorder Hearing loss
7 (18%) 3 (8%) 3 (8%)
Tinnitus Lower cranial nerve disorder Dysphagia Dysarthria
1 (3%) 4 (11%) 3 (8%) 2 (5%)
Highlights: • This is the third case of trochlear schwannoma arising from pineal region, and the first case to be resected using a paramedian infratentorial supracerebellar approach. • A literature review of all previously reported cases of trochlear schwannoma indicated that trochlear nerve palsy was present initially in only 50% of cases. • The possibility of trochlear schwannoma should be considered when a mass is identified in the pineal region or along the free tentorial edge. • A rational treatment algorithm for trochlear schwannoma that seeks to maximize functional outcome is illustrated in this article.
Abbreviations: CT: Computed tomography MRI: Magnetic resonance imaging
Declaration of Interest: None