Primary fourth ventricular meningioma: case report and review of the literature.

Primary fourth ventricle meningiomas are extremely rare, and they are defined as meningiomas arising from the choroid plexus and lying strictly within the fourth ventricle. In this report we present a 61-year-old man with progressive worsening vertigo and gait disturbance, and new onset of diplopia. Neurological examination revealed bilateral abducens nerve paralysis, horizontal nystagmus, and gait disturbance with truncal ataxia. Neuroimaging revealed a mass lesion in the fourth ventricle with brain stem compression, and obstructive hydrocephalus. The patient was operated in the prone position with suboccipital craniotomy and splitting the lower vermis. Total resection of the tumor was achieved with no intra- or post-operative complications. Histopathologic examination revealed fibroblastic type meningioma (WHO grade I).