- Email: [email protected]
Schwannoma of the Fourth Ventricle: The Eighth Case Report
Case Report
Schwannoma of the Fourth Ventricle: The Eighth Case Report Maria M. Santos1, Aˆngela Timo´teo2, Domingos Coiteiro1, Jose´ Pimentel3
Key words Brain tumor - Fourth ventricle tumor - Intra-axial schwannoma -
Abbreviations and Acronyms MRI: Magnetic resonance imaging VP: ventriculoperitoneal From the Departments of 1Neurological Surgery and 3 Neuropathology, Centro Hospitalar Lisboa Norte, Entidade Pública Empresarial, Lisbon; and 2Department of Neurology, Hospital Fernando Fonseca, Amadora, Portugal To whom correspondence should be addressed: Maria M. Santos, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2015). http://dx.doi.org/10.1016/j.wneu.2015.04.036 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2015 Elsevier Inc. All rights reserved.
- OBJECTIVE:
We report an uncommon case of a surgical resection of a fourth ventricle tumor in an adult that proved to be a schwannoma.
- METHODS:
A 53-year-old man presented with a 1.5-year history of gait unsteadiness and vertigo and a few-week history of headache, emesis, and neurogenic dysphagia. A brain magnetic resonance imaging revealed a large, heterogeneously contrast enhancing mass located within the fourth ventricle, compressing the brainstem and causing supratentorial ventricle enlargement. A suboccipital craniotomy and a telovelar approach were performed to resect the tumor. The ventricular system was repermeabilized at the end of the operation.
- RESULTS:
A postoperative magnetic resonance imaging confirmed complete tumor removal. There was an initial worsening of the preoperative deficits, which progressively improved. The tumor was classified as a fourth ventricle schwannoma. There has been no evidence of tumor recurrence during the 6 years of follow-up. At present, the patient is ambulatory and reports an intermittent diplopia on conjugated gaze.
- CONCLUSION:
This case report intends to reveal the eighth case of a fourth ventricle schwannoma since 1957. Schwannomas of the fourth ventricle are infrequent but should be accounted in the differential diagnosis of spaceoccupying lesions in this location. Gross total resection might be the definite treatment of these tumors if deemed possible.
INTRODUCTION Schwannomas arise from the myelin sheath of peripheral nerves and account for 8% of all intracranial tumors. Although most commonly encountered in extra-axial locations, intra-axial schwannomas have been reported, including intraventricular lesions (4, 5, 7, 8, 13, 20, 25, 27). Tumors arising specifically in the fourth ventricle are extremely rare and only 7 case reports have been described to date (14, 16, 18, 22, 29). Because Schwann cells do not cover the central nervous system, theories trying to explain the occurrence of intra-axial schwannomas are speculative (2, 4, 6-8, 12, 13, 16, 17, 19, 20, 22, 28, 29). The aim of this report is to present the eighth case of a fourth ventricle schwannoma, which differs from the previously reported ones for its dimension and enriched neurological examination. A literature review focusing on this particular topography for schwannoma occurrence and its particular etiopathogenesis is also undertaken.
CASE REPORT A 53-year-old man presented with progressive gait unsteadiness during the past 18 months and chronic vertigo. Few weeks before admission, he reported severe headaches, vomiting, and increasing dysphagia. His past medical history was unremarkable and there was no family history of neurofibromatosis. No café au lait spots were found on skin examination. The neurological examination showed a saccadic horizontal nystagmus, assymetrical palate elevation, broad-based gait, and truncal ataxia. The remaining cranial nerves were normal and there were no signs of motor or sensitive pathways dysfunction. A brain magnetic resonance imaging (MRI) revealed a large, contrast-enhancing, irregularly spherical, fourth ventricular tumor (4 4 3.9 cm) suggestive of choroid plexus papilloma or ependymoma. There was evidence of brainstem compression and the ventricles were enlarged despite no
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signs of active hydrocephalus (Figure 1). Surgical treatment was recommended. Operation and Postoperative Course The patient was positioned prone with the head flexed. A midline incision was done extending from the inion to C2. A suboccipital craniotomy was performed down to the foramen magnum and the posterior arch of C1 was removed. After opening the dura mater, the cerebellar tonsils were gently retracted. Opening of the tela choroidea and the inferior portion of the inferior medullary velum exposed a yellowish mass occupying most of the fourth ventricle. After internal debulking of the tumor, it was meticulously dissected from the floor of the fourth ventricle, where it was adherent. A total resection was achieved. Transient new neurological deficits were induced and included VI, IX and X nerve palsies and ataxia worsening. On postoperative day 9, a percutaneous endoscopic
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CASE REPORT MARIA M. SANTOS ET AL.
SCHWANNOMA OF THE FOURTH VENTRICLE
Figure 1. Preoperative T1 weighted magnetic resonance imaging after gadolinium administration. (A) Axial view; (B) sagittal view; (C) coronal view.
gastrostomy tube was inserted, mechanical ventilation was discontinued, and the patient was started on rehabilitation therapy. He was discharged 5 weeks later to a rehabilitation center. The gait progressively improved during 6 months, when he could ambulate without assistance. The percutaneous endoscopic gastrostomy tube was removed 1 year after the procedure. A mild intermittent diplopia was unchanged. The 1-year follow-up brain MRI showed no residual tumor (Figure 2) and there is no evidence of tumor recurrence 6 years after surgery. Microscopic Examination The tumor consisted mainly of areas of compact architecture with elongated bipolar cells arranged in fascicles, long club-shaped nuclei, and the so-called Antoni A tissue. Rarer, a loose-textured Antoni B tissue was
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elicited (Figure 3A). Tumor cells were strongly and uniformly immunoreactive for S-100 protein (Figure 3B). The interface between tumor and cerebral parenchyma from where it probably arose was illdefined and showed abundant Rosenthal fibers (Figure 3C). Schwannoma of the fourth ventricle was the histologic diagnosis. DISCUSSION Schwannomas correspond to 8% of brain tumors and 25% of spinal tumors (22). Most (95%) are extra-axial, but they can also be found within the brain and spinal cord parenchyma or ventricular system (4, 16). The intraventricular location is the least common, with no more than 20 cases reported since 1950 (18), comprising 1 case in the third ventricle (17), 12 in the lateral ventricles (2, 4-8, 11-13, 19, 20, 25, 28), and 7 cases in the fourth ventricle (10, 14, 16,
18, 22, 29). The first fourth ventricle schwannoma ever reported (in 1957) was malignant and diagnosed postmortem (14). The current report is, to our knowledge, the eighth description of a fourth ventricle schwannoma (Table 1). A presumptive diagnosis based on MRI features is rather difficult, as intraventricular schwannomas do not have unique characteristics. Ependymoma, choroid plexus papilloma, and juvenile pilocytic astrocytoma are common-enhancing tumors of the fourth ventricle and may encompass the differential diagnosis. Age and gender are not contributory to the diagnosis. The symptoms (mainly headaches) and the neurological signs (cerebellar and cranial nerve signs) are unspecific. Duration of symptoms can easily be longer than 1 year. The postoperative course is mostly related to preoperative deficits, tumor size, and floor invasion of the fourth ventricle. In the current case report, significant postoperative deficits were temporarily induced, but a mild diplopia was the only fixed neurological deficit. It should be noted that this tumor was the largest one reported to date. There were no descriptions of tumor recurrence on the previously published 7 surgical cases, which is in accord with the benign nature of these tumors. Although recurrence might be rare, MRI surveillance is warranted, particularly if total resection is not achieved. To our knowledge, there are no Schwann cells covering central nervous system fibers. Schwann cells are present in peripheral fibers and in autonomic tissue surrounding vessels. A few investigators defend a single etiopathogenic theory (9, 22, 24), which would explain any intra-axial occurrence of a schwannoma, whereas others (4, 29) believe in a plurietiology model to explain the ectopy of this neoplasm. These attempts to explain the finding of intraspinal or intracerebral schwannomas can be extrapolated to the even least common ventricular schwannomas (17). Benedickt (3), in 1874, first described nerve fibers (covered by Schwann cells) in the choroids plexus of the fourth ventricle. Stöhr (26), in 1922, and Rigs and Clary, in 1957 (23) suggested a neoplastic growth/ hyperplasia of Schwann cells of the autonomic nervous fibers covering the arteries and the choroid plexus of the central nervous system. Adelman and
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2015.04.036
CASE REPORT MARIA M. SANTOS ET AL.
Figure 2. Postoperative T1 weighted magnetic resonance imaging after gadolinium administration. (A) Axial view; (B) sagittal view; (C) coronal view.
Figure 3. Microscopic examination of the fourth ventricle tumor. (A) Antoni A (left) and Antoni B (right) tissue of the schwannoma (hematoxylin and eosin [H&E] 40); (B) Fusiform elements with strongly S-100 protein
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SCHWANNOMA OF THE FOURTH VENTRICLE
Aronson (1), in 1972, and Russel and Rubinstein (24), in 1977, proposed that proliferation of primary mesenchymal cells could form foci of differentiated Schwann cells and used the term schwannosis for these groups of cells responsive to different stimuli (e.g., metabolic, traumatic). In 1990, Redekop et al. (22) reported a case of a 7-year-old boy with a fourth ventricle schwannoma and justified its occurrence as a result of a failed migration of neural crest cells during embryogenesis and consequent neoplastic proliferation of an ectopic population of cells—a theory that was originally developed by Ramamurthy et al. (21). In 1993, Weiner et al. (29), reported on 2 of their cases of fourth ventricle schwannomas as a proliferation of Schwann cells in the nerve root entry zone where the pia mater starts the covering of the previously myelin-sheathed fibers (the “critical area” from Mason and Keigher (15)). In summary, a fourth ventricle schwannoma results from a monoclonal proliferation of Schwann cells that are ectopically placed in the fourth ventricle. This ectopy can be consecutive to 1) a disorder of embryogenesis resulting in neural crest cells failed migration; 2) proliferation of the small amount of Schwann cells covering the choroid plexus and arteries of the fourth ventricle; or 3) transformation of undifferentiated mesenchymal cells presented in the fourth ventricle to differentiated Schwann cells. Although the first hypothesis seems suitable to explain the occurrence of these tumors in children (like the one reported
immunoreactivity (10); (C) Transition between tumor (right) and normal parenchyma (left) (H&E 10).
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CASE REPORT MARIA M. SANTOS ET AL.
SCHWANNOMA OF THE FOURTH VENTRICLE
Table 1. Clinical and Imaging Features of the Previously Reported Fourth Ventricle Schwannomas
Reference
Duration Age of (years) Sex Symptoms
Symptoms/Signs
Size
Associated Hydrocephalus
Extension of the Resection Postoperative Comments
Marchand et al., 1957 (14)
43
M
4.5 years Psychiatric disorder, headache, ataxic gait
“petite noix”
No
Autopsy
Dead
Redekop et al., 1990 (22)
7
M
5 months Inward deviation of the left eye, left facial palsy, nystagmus, left dysdiadochokinesia
1.1 1.3 cm
No
Subtotal
Previous deficits þ left side ataxia
Weiner et al., 1993 (29)
61
M 1.5 months Right hemifacial spasm, right facial palsy, neck pain, right arm dismetry and dysdiadochokinesia, ataxic gait
Large
Yes
Subtotal
Increasing hydrocephalus (VP Shunt), improved ataxia, unchanged facial spasm and palsy
Weiner et al., 1993 (29)
78
F
7 months Right hemifacial spasm, diplopia, dysartric speech, right facial palsy, horizontal nystagmus, ataxic gait
Large
Yes
Subtotal
Resolved diplopia, unchanged remaining deficits
Mastache et al., 2002 (16)
36
F
9 months Vertigo, headache, ataxic gait, right nystagmus, dysdiadochokinesia and dismetry
4 3.8 cm
No
Total
Right dismetry; independent
Oertel et al., 2009 (18)
71
F
2 months Transient scintillating scotomas
1.5 cm
No
Total
No deficits
Hodges et al., (2011) (10)
69
M
1.8 1.8 2 cm
No
Total
Present case
53
M
4 3.9 cm
No
Total
-
Generalized weakness, gait instability, memory disturbances
1.5 years Vertigo, headaches, vomiting, dysphagia, ataxic gait, nystagmus
Transient dysphagia, permanently diplopia; independent
VP Shunt, ventriculoperitoneal shunt.
by Redekop et al. (22)), the second and the third hypotheses can probably be applied to older ages.
CONCLUSION Despite being uncommon tumors, schwannomas should be considered in the differential diagnosis of fourth ventricle space-occupying lesions. Several hypotheses have been raised to explain the presence of a Schwann cell tumor in the fourth ventricle, however, at present, no single theory is consensually accepted. Gross total resection should be attempted if tumor dissection from the floor of the fourth ventricle is deemed possible without incurring additional neurological deficits. Subtotal resection is a valid option when more aggressive dissection of the fourth ventricle’s floor is required. REFERENCES 1. Adelman LS, Aronson SM: Intramedullary nerve fiber and Schwann cell proliferation within the
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spinal cord (schwannosis). Neurology 22:726-731, 1972. 2. Barbosa MD, Rebelo O, Barbosa P, Gonçalves J, Fernandes R: Cystic intraventricular schwannoma: case report and review of the literature. Neurocirurgía (Astur) 12:56-60, 2001.
9. Herregodts P, Vloeberghs M, Schmedding E, Goossens A, Stadnik T, D’Haens J: Solitary dorsal intramedullary schwannoma: case report. J Neurosurg 74:816-820, 1991.
3. Benedickt M: The innervation of the choroid plexus [in German]. Virschows Arch Pathol Anat 59:395-400, 1874.
10. Hodges TR, Karikari IO, Nimjee SM, Tibaleka J, Cummings TJ, Radhakrishnan S, Friedman AH: Fourth ventricular schwannoma: identical clinicopathologic features as Schwann cell-derived schwannoma with unique etiopathologic origins. Case Rep Med 2011:1-4, 2011.
4. Benedict WJ, Brown HG, Sivarajan G, Prabhu VC: Intraventricular schwannoma in a 15-year-old adolescent: a case report. Child Nerv Syst 24: 529-532, 2008.
11. Jaimovich R, Jaimovich SG, Arakaki N, Sevlever G: Supratentorial intraventricular solitary schwannoma. Case report and literature review. Childs Nerv Syst 29:499-504, 2013.
5. David M, Guyot JF, Sachs M, Ballivet J: Schwannoma of the lateral ventricle [in French]. Neurochirurgie 11:578-581, 1965. 6. Dow GR, Hussein A, Robertson IJ: Supratentorial intraventricular schwannoma. Br J Neurosurg 18: 561-562, 2004. 7. Erdogan E, Onguru O, Bulakbasi N, Baysefer A, Gezen F, Timurkaynak E: Schwannoma of the lateral venticle: eight year follow-up and literature review. Minim Invasive Neurosurg 46:50-53, 2003. 8. Ghatak NR, Norwood CW, Davis CH: Intracerebral schwannoma. Surg Neurol 3:45-57, 1975.
12. Jung JM, Shin HJ, Chi JG, Park IS, Kim ES, Han JW: Malignant intraventricular schwannoma. Case report. J Neurosurg 82:121-124, 1995. 13. Lévêque M, Gilliard C, Godfraind C, Ruchoux MM, Gustin T: Intraventricular schwannoma: a case report [in French]. Neurochirurgie 53:383-386, 2007. 14. Marchand L, Koechlin P, Racine Y: Malignant neurinoma of the fourth ventricle with medullary propagation on a schizophrenic. Death after an electroshock [in French]. Ann Med Psychol (Paris) 115:108-113, 1957.
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2015.04.036
CASE REPORT MARIA M. SANTOS ET AL.
15. Mason TH, Keigher HA: Intramedullary spinal cord neurilemmoma of the cervical spinal cord. Case report. J Neurosurg 29:414-441, 1968. 16. Mastache J, Rodriguéz G, Garcia R, Garciduenas A: Schwannoma of the fourth ventricle. Case description and literature review [in Spanish]. Rev Med IMSS 40:405-408, 2002. 17. Messing-Junger AM, Riemenschneider MJ, Reifenberger G: A 21-year-old female with a third ventricular tumor. Brain Pathol 16:87-88, 2006. 18. Oertel M, Nolte K, Blaum M, Weiss J, Gilsbach J, Korinth M: Primary intraventricular schwannomas. Clin Neurol Neurosurg 111:768-773, 2009.
SCHWANNOMA OF THE FOURTH VENTRICLE
21. Ramamurthy B, Anguli VC, Iyer CG: A case of intramedullary neurinoma. J Neurol Neurosurg Psychiatry 21:92-94, 1958.
28. Vasconcellos L, Santos A, Veiga J, Schilemann I, Lancellotti C: Supratentorial intraventricular schwannoma of the choroid plexus. Arq Neuropsiquiatr 67:1100-1102, 2009.
22. Redekop G, Elisevich K, Gilbert J: Fourth ventricular schwannoma. J Neurosurg 73:777-781, 1990. 23. Rigs HE, Clary WU: A case of intramedullary sheath cell tumor of the spinal cord. Consideration of vascular nerves as a source of origin. J Neuropathol Exp Neurol 16:332-336, 1957. 24. Russel DS, Rubinstein LJ: Pathology of Tumours of the Nervous System. 4th ed. London: Edward Arnold; 1977. 25. Schalit MN, Toledo E, Sandbank U: Intracerebral schwannoma. Acta Neurochir 64:253-258, 1982.
29. Weiner H, Zagzag D, Babu R, Weinreb H, Ransohoff J: Schwannoma of the fourth ventricle presenting with hemifacial spasm. A report of two cases. J Neuro-Oncol 15:37-43, 1993.
Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Received 17 February 2015; accepted 16 April 2015
19. Ost AH, Meyer R: Cystic intraventricular schwannoma: a case report. AJNR Am J Neuroradiol 11: 1262-1264, 1990. 20. Pimentel J, Tavora L, Cristina M, Antunes J: Intraventricular schwannoma. Childs Nerv Syst 4: 373-375, 1988.
26. Stöhr P: Choroid plexus innervation from menschen [in German]. U Z Gesamte Anat 63:562-607, 1922.
Citation: World Neurosurg. (2015). http://dx.doi.org/10.1016/j.wneu.2015.04.036 Journal homepage: www.WORLDNEUROSURGERY.org
27. Van Rensburg MJ, Proctor NSF, Danziger J, Orelowitz MS: Temporal lobe epilepsy due to an intracerebral schwannoma: case report. J Neurol Neurosurg Psychiatry 38:703-709, 1975.
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Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2015 Elsevier Inc. All rights reserved.
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Schwannoma of the Fourth Ventricle: The Eighth Case Report Maria M. Santos1, Aˆngela Timo´teo2, Domingos Coiteiro1, Jose´ Pimentel3
Key words Brain tumor - Fourth ventricle tumor - Intra-axial schwannoma -
Abbreviations and Acronyms MRI: Magnetic resonance imaging VP: ventriculoperitoneal From the Departments of 1Neurological Surgery and 3 Neuropathology, Centro Hospitalar Lisboa Norte, Entidade Pública Empresarial, Lisbon; and 2Department of Neurology, Hospital Fernando Fonseca, Amadora, Portugal To whom correspondence should be addressed: Maria M. Santos, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2015). http://dx.doi.org/10.1016/j.wneu.2015.04.036 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2015 Elsevier Inc. All rights reserved.
- OBJECTIVE:
We report an uncommon case of a surgical resection of a fourth ventricle tumor in an adult that proved to be a schwannoma.
- METHODS:
A 53-year-old man presented with a 1.5-year history of gait unsteadiness and vertigo and a few-week history of headache, emesis, and neurogenic dysphagia. A brain magnetic resonance imaging revealed a large, heterogeneously contrast enhancing mass located within the fourth ventricle, compressing the brainstem and causing supratentorial ventricle enlargement. A suboccipital craniotomy and a telovelar approach were performed to resect the tumor. The ventricular system was repermeabilized at the end of the operation.
- RESULTS:
A postoperative magnetic resonance imaging confirmed complete tumor removal. There was an initial worsening of the preoperative deficits, which progressively improved. The tumor was classified as a fourth ventricle schwannoma. There has been no evidence of tumor recurrence during the 6 years of follow-up. At present, the patient is ambulatory and reports an intermittent diplopia on conjugated gaze.
- CONCLUSION:
This case report intends to reveal the eighth case of a fourth ventricle schwannoma since 1957. Schwannomas of the fourth ventricle are infrequent but should be accounted in the differential diagnosis of spaceoccupying lesions in this location. Gross total resection might be the definite treatment of these tumors if deemed possible.
INTRODUCTION Schwannomas arise from the myelin sheath of peripheral nerves and account for 8% of all intracranial tumors. Although most commonly encountered in extra-axial locations, intra-axial schwannomas have been reported, including intraventricular lesions (4, 5, 7, 8, 13, 20, 25, 27). Tumors arising specifically in the fourth ventricle are extremely rare and only 7 case reports have been described to date (14, 16, 18, 22, 29). Because Schwann cells do not cover the central nervous system, theories trying to explain the occurrence of intra-axial schwannomas are speculative (2, 4, 6-8, 12, 13, 16, 17, 19, 20, 22, 28, 29). The aim of this report is to present the eighth case of a fourth ventricle schwannoma, which differs from the previously reported ones for its dimension and enriched neurological examination. A literature review focusing on this particular topography for schwannoma occurrence and its particular etiopathogenesis is also undertaken.
CASE REPORT A 53-year-old man presented with progressive gait unsteadiness during the past 18 months and chronic vertigo. Few weeks before admission, he reported severe headaches, vomiting, and increasing dysphagia. His past medical history was unremarkable and there was no family history of neurofibromatosis. No café au lait spots were found on skin examination. The neurological examination showed a saccadic horizontal nystagmus, assymetrical palate elevation, broad-based gait, and truncal ataxia. The remaining cranial nerves were normal and there were no signs of motor or sensitive pathways dysfunction. A brain magnetic resonance imaging (MRI) revealed a large, contrast-enhancing, irregularly spherical, fourth ventricular tumor (4 4 3.9 cm) suggestive of choroid plexus papilloma or ependymoma. There was evidence of brainstem compression and the ventricles were enlarged despite no
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signs of active hydrocephalus (Figure 1). Surgical treatment was recommended. Operation and Postoperative Course The patient was positioned prone with the head flexed. A midline incision was done extending from the inion to C2. A suboccipital craniotomy was performed down to the foramen magnum and the posterior arch of C1 was removed. After opening the dura mater, the cerebellar tonsils were gently retracted. Opening of the tela choroidea and the inferior portion of the inferior medullary velum exposed a yellowish mass occupying most of the fourth ventricle. After internal debulking of the tumor, it was meticulously dissected from the floor of the fourth ventricle, where it was adherent. A total resection was achieved. Transient new neurological deficits were induced and included VI, IX and X nerve palsies and ataxia worsening. On postoperative day 9, a percutaneous endoscopic
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CASE REPORT MARIA M. SANTOS ET AL.
SCHWANNOMA OF THE FOURTH VENTRICLE
Figure 1. Preoperative T1 weighted magnetic resonance imaging after gadolinium administration. (A) Axial view; (B) sagittal view; (C) coronal view.
gastrostomy tube was inserted, mechanical ventilation was discontinued, and the patient was started on rehabilitation therapy. He was discharged 5 weeks later to a rehabilitation center. The gait progressively improved during 6 months, when he could ambulate without assistance. The percutaneous endoscopic gastrostomy tube was removed 1 year after the procedure. A mild intermittent diplopia was unchanged. The 1-year follow-up brain MRI showed no residual tumor (Figure 2) and there is no evidence of tumor recurrence 6 years after surgery. Microscopic Examination The tumor consisted mainly of areas of compact architecture with elongated bipolar cells arranged in fascicles, long club-shaped nuclei, and the so-called Antoni A tissue. Rarer, a loose-textured Antoni B tissue was
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elicited (Figure 3A). Tumor cells were strongly and uniformly immunoreactive for S-100 protein (Figure 3B). The interface between tumor and cerebral parenchyma from where it probably arose was illdefined and showed abundant Rosenthal fibers (Figure 3C). Schwannoma of the fourth ventricle was the histologic diagnosis. DISCUSSION Schwannomas correspond to 8% of brain tumors and 25% of spinal tumors (22). Most (95%) are extra-axial, but they can also be found within the brain and spinal cord parenchyma or ventricular system (4, 16). The intraventricular location is the least common, with no more than 20 cases reported since 1950 (18), comprising 1 case in the third ventricle (17), 12 in the lateral ventricles (2, 4-8, 11-13, 19, 20, 25, 28), and 7 cases in the fourth ventricle (10, 14, 16,
18, 22, 29). The first fourth ventricle schwannoma ever reported (in 1957) was malignant and diagnosed postmortem (14). The current report is, to our knowledge, the eighth description of a fourth ventricle schwannoma (Table 1). A presumptive diagnosis based on MRI features is rather difficult, as intraventricular schwannomas do not have unique characteristics. Ependymoma, choroid plexus papilloma, and juvenile pilocytic astrocytoma are common-enhancing tumors of the fourth ventricle and may encompass the differential diagnosis. Age and gender are not contributory to the diagnosis. The symptoms (mainly headaches) and the neurological signs (cerebellar and cranial nerve signs) are unspecific. Duration of symptoms can easily be longer than 1 year. The postoperative course is mostly related to preoperative deficits, tumor size, and floor invasion of the fourth ventricle. In the current case report, significant postoperative deficits were temporarily induced, but a mild diplopia was the only fixed neurological deficit. It should be noted that this tumor was the largest one reported to date. There were no descriptions of tumor recurrence on the previously published 7 surgical cases, which is in accord with the benign nature of these tumors. Although recurrence might be rare, MRI surveillance is warranted, particularly if total resection is not achieved. To our knowledge, there are no Schwann cells covering central nervous system fibers. Schwann cells are present in peripheral fibers and in autonomic tissue surrounding vessels. A few investigators defend a single etiopathogenic theory (9, 22, 24), which would explain any intra-axial occurrence of a schwannoma, whereas others (4, 29) believe in a plurietiology model to explain the ectopy of this neoplasm. These attempts to explain the finding of intraspinal or intracerebral schwannomas can be extrapolated to the even least common ventricular schwannomas (17). Benedickt (3), in 1874, first described nerve fibers (covered by Schwann cells) in the choroids plexus of the fourth ventricle. Stöhr (26), in 1922, and Rigs and Clary, in 1957 (23) suggested a neoplastic growth/ hyperplasia of Schwann cells of the autonomic nervous fibers covering the arteries and the choroid plexus of the central nervous system. Adelman and
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2015.04.036
CASE REPORT MARIA M. SANTOS ET AL.
Figure 2. Postoperative T1 weighted magnetic resonance imaging after gadolinium administration. (A) Axial view; (B) sagittal view; (C) coronal view.
Figure 3. Microscopic examination of the fourth ventricle tumor. (A) Antoni A (left) and Antoni B (right) tissue of the schwannoma (hematoxylin and eosin [H&E] 40); (B) Fusiform elements with strongly S-100 protein
WORLD NEUROSURGERY - [-]: ---, MONTH 2015
SCHWANNOMA OF THE FOURTH VENTRICLE
Aronson (1), in 1972, and Russel and Rubinstein (24), in 1977, proposed that proliferation of primary mesenchymal cells could form foci of differentiated Schwann cells and used the term schwannosis for these groups of cells responsive to different stimuli (e.g., metabolic, traumatic). In 1990, Redekop et al. (22) reported a case of a 7-year-old boy with a fourth ventricle schwannoma and justified its occurrence as a result of a failed migration of neural crest cells during embryogenesis and consequent neoplastic proliferation of an ectopic population of cells—a theory that was originally developed by Ramamurthy et al. (21). In 1993, Weiner et al. (29), reported on 2 of their cases of fourth ventricle schwannomas as a proliferation of Schwann cells in the nerve root entry zone where the pia mater starts the covering of the previously myelin-sheathed fibers (the “critical area” from Mason and Keigher (15)). In summary, a fourth ventricle schwannoma results from a monoclonal proliferation of Schwann cells that are ectopically placed in the fourth ventricle. This ectopy can be consecutive to 1) a disorder of embryogenesis resulting in neural crest cells failed migration; 2) proliferation of the small amount of Schwann cells covering the choroid plexus and arteries of the fourth ventricle; or 3) transformation of undifferentiated mesenchymal cells presented in the fourth ventricle to differentiated Schwann cells. Although the first hypothesis seems suitable to explain the occurrence of these tumors in children (like the one reported
immunoreactivity (10); (C) Transition between tumor (right) and normal parenchyma (left) (H&E 10).
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CASE REPORT MARIA M. SANTOS ET AL.
SCHWANNOMA OF THE FOURTH VENTRICLE
Table 1. Clinical and Imaging Features of the Previously Reported Fourth Ventricle Schwannomas
Reference
Duration Age of (years) Sex Symptoms
Symptoms/Signs
Size
Associated Hydrocephalus
Extension of the Resection Postoperative Comments
Marchand et al., 1957 (14)
43
M
4.5 years Psychiatric disorder, headache, ataxic gait
“petite noix”
No
Autopsy
Dead
Redekop et al., 1990 (22)
7
M
5 months Inward deviation of the left eye, left facial palsy, nystagmus, left dysdiadochokinesia
1.1 1.3 cm
No
Subtotal
Previous deficits þ left side ataxia
Weiner et al., 1993 (29)
61
M 1.5 months Right hemifacial spasm, right facial palsy, neck pain, right arm dismetry and dysdiadochokinesia, ataxic gait
Large
Yes
Subtotal
Increasing hydrocephalus (VP Shunt), improved ataxia, unchanged facial spasm and palsy
Weiner et al., 1993 (29)
78
F
7 months Right hemifacial spasm, diplopia, dysartric speech, right facial palsy, horizontal nystagmus, ataxic gait
Large
Yes
Subtotal
Resolved diplopia, unchanged remaining deficits
Mastache et al., 2002 (16)
36
F
9 months Vertigo, headache, ataxic gait, right nystagmus, dysdiadochokinesia and dismetry
4 3.8 cm
No
Total
Right dismetry; independent
Oertel et al., 2009 (18)
71
F
2 months Transient scintillating scotomas
1.5 cm
No
Total
No deficits
Hodges et al., (2011) (10)
69
M
1.8 1.8 2 cm
No
Total
Present case
53
M
4 3.9 cm
No
Total
-
Generalized weakness, gait instability, memory disturbances
1.5 years Vertigo, headaches, vomiting, dysphagia, ataxic gait, nystagmus
Transient dysphagia, permanently diplopia; independent
VP Shunt, ventriculoperitoneal shunt.
by Redekop et al. (22)), the second and the third hypotheses can probably be applied to older ages.
CONCLUSION Despite being uncommon tumors, schwannomas should be considered in the differential diagnosis of fourth ventricle space-occupying lesions. Several hypotheses have been raised to explain the presence of a Schwann cell tumor in the fourth ventricle, however, at present, no single theory is consensually accepted. Gross total resection should be attempted if tumor dissection from the floor of the fourth ventricle is deemed possible without incurring additional neurological deficits. Subtotal resection is a valid option when more aggressive dissection of the fourth ventricle’s floor is required. REFERENCES 1. Adelman LS, Aronson SM: Intramedullary nerve fiber and Schwann cell proliferation within the
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spinal cord (schwannosis). Neurology 22:726-731, 1972. 2. Barbosa MD, Rebelo O, Barbosa P, Gonçalves J, Fernandes R: Cystic intraventricular schwannoma: case report and review of the literature. Neurocirurgía (Astur) 12:56-60, 2001.
9. Herregodts P, Vloeberghs M, Schmedding E, Goossens A, Stadnik T, D’Haens J: Solitary dorsal intramedullary schwannoma: case report. J Neurosurg 74:816-820, 1991.
3. Benedickt M: The innervation of the choroid plexus [in German]. Virschows Arch Pathol Anat 59:395-400, 1874.
10. Hodges TR, Karikari IO, Nimjee SM, Tibaleka J, Cummings TJ, Radhakrishnan S, Friedman AH: Fourth ventricular schwannoma: identical clinicopathologic features as Schwann cell-derived schwannoma with unique etiopathologic origins. Case Rep Med 2011:1-4, 2011.
4. Benedict WJ, Brown HG, Sivarajan G, Prabhu VC: Intraventricular schwannoma in a 15-year-old adolescent: a case report. Child Nerv Syst 24: 529-532, 2008.
11. Jaimovich R, Jaimovich SG, Arakaki N, Sevlever G: Supratentorial intraventricular solitary schwannoma. Case report and literature review. Childs Nerv Syst 29:499-504, 2013.
5. David M, Guyot JF, Sachs M, Ballivet J: Schwannoma of the lateral ventricle [in French]. Neurochirurgie 11:578-581, 1965. 6. Dow GR, Hussein A, Robertson IJ: Supratentorial intraventricular schwannoma. Br J Neurosurg 18: 561-562, 2004. 7. Erdogan E, Onguru O, Bulakbasi N, Baysefer A, Gezen F, Timurkaynak E: Schwannoma of the lateral venticle: eight year follow-up and literature review. Minim Invasive Neurosurg 46:50-53, 2003. 8. Ghatak NR, Norwood CW, Davis CH: Intracerebral schwannoma. Surg Neurol 3:45-57, 1975.
12. Jung JM, Shin HJ, Chi JG, Park IS, Kim ES, Han JW: Malignant intraventricular schwannoma. Case report. J Neurosurg 82:121-124, 1995. 13. Lévêque M, Gilliard C, Godfraind C, Ruchoux MM, Gustin T: Intraventricular schwannoma: a case report [in French]. Neurochirurgie 53:383-386, 2007. 14. Marchand L, Koechlin P, Racine Y: Malignant neurinoma of the fourth ventricle with medullary propagation on a schizophrenic. Death after an electroshock [in French]. Ann Med Psychol (Paris) 115:108-113, 1957.
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2015.04.036
CASE REPORT MARIA M. SANTOS ET AL.
15. Mason TH, Keigher HA: Intramedullary spinal cord neurilemmoma of the cervical spinal cord. Case report. J Neurosurg 29:414-441, 1968. 16. Mastache J, Rodriguéz G, Garcia R, Garciduenas A: Schwannoma of the fourth ventricle. Case description and literature review [in Spanish]. Rev Med IMSS 40:405-408, 2002. 17. Messing-Junger AM, Riemenschneider MJ, Reifenberger G: A 21-year-old female with a third ventricular tumor. Brain Pathol 16:87-88, 2006. 18. Oertel M, Nolte K, Blaum M, Weiss J, Gilsbach J, Korinth M: Primary intraventricular schwannomas. Clin Neurol Neurosurg 111:768-773, 2009.
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21. Ramamurthy B, Anguli VC, Iyer CG: A case of intramedullary neurinoma. J Neurol Neurosurg Psychiatry 21:92-94, 1958.
28. Vasconcellos L, Santos A, Veiga J, Schilemann I, Lancellotti C: Supratentorial intraventricular schwannoma of the choroid plexus. Arq Neuropsiquiatr 67:1100-1102, 2009.
22. Redekop G, Elisevich K, Gilbert J: Fourth ventricular schwannoma. J Neurosurg 73:777-781, 1990. 23. Rigs HE, Clary WU: A case of intramedullary sheath cell tumor of the spinal cord. Consideration of vascular nerves as a source of origin. J Neuropathol Exp Neurol 16:332-336, 1957. 24. Russel DS, Rubinstein LJ: Pathology of Tumours of the Nervous System. 4th ed. London: Edward Arnold; 1977. 25. Schalit MN, Toledo E, Sandbank U: Intracerebral schwannoma. Acta Neurochir 64:253-258, 1982.
29. Weiner H, Zagzag D, Babu R, Weinreb H, Ransohoff J: Schwannoma of the fourth ventricle presenting with hemifacial spasm. A report of two cases. J Neuro-Oncol 15:37-43, 1993.
Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Received 17 February 2015; accepted 16 April 2015
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Citation: World Neurosurg. (2015). http://dx.doi.org/10.1016/j.wneu.2015.04.036 Journal homepage: www.WORLDNEUROSURGERY.org
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