Schwannoma of the Fourth Ventricle: Report of Two Cases and Review of Literature.

Abstract

Schwannomas have been reported in several unusual intracranial locations. Here we report 2 cases of extremely rare schwannomas originating in the fourth ventricle, without attachment to the surrounding structures. The clinical course, radiologic and pathological features, treatment, and follow-up are described. Case 1 was a 49-year-old man who presented with symptoms of paroxysmal dizziness and vomiting. Magnetic resonance imaging (MRI) showed a mixed solid-cystic mass occupying the inferior half of the fourth ventricle. Complete excision of the tumor was performed via midline suboccipital craniectomy. The histological diagnosis was intraventricular schwannoma. Case 2 was an 18-year-old man with chronic vertigo and progressive gait unsteadiness. MRI revealed a heterogeneously enhancing lesion completely filling the fourth ventricle. An Ommaya tube was placed in the ventricle to relieve symptoms of hydrocephalus, followed by tumor resection performed via a suboccipital craniotomy. Histopathological examination confirmed the diagnosis of schwannoma. Fourth ventricular schwannomas are rare but should be considered in the differential diagnosis of contrast-enhancing intraventricular tumors in both children and adults. Although their etiopathological origin may differ from that of extra-axial schwannomas, their imaging, histology, and clinical course appear to be identical, and these tumors should be managed similarly.