Case ReportSchwannoma of the Fourth Ventricle: The Eighth Case Report
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, 7, 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.
Section snippets
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
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, 5, 6, 7, 8, 11, 12, 13, 19, 20, 25, 28, and 7 cases in the fourth ventricle 10, 14, 16, 18, 22, 29. The first
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
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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.