Surgical Approaches for Lateral Ventricular Trigone Meningioma

Intraventricular meningiomas account for 9.8-14% of all intraventricular tumors and for 20% of lateral ventricle tumors [1,2]. Meningiomas of the lateral ventricle constitute 0.5-4.5% of all intracranial meningiomas [3,4]. Between 60% and 94% of them arise from the choroid plexus at the trigone. The predilection for the trigone may be attributed to the abundance of choroid plexus arachnoidea. The clinical manifestations of lateral ventricular meningiomas depend on the tumor size [5]: A small tumor causes no clinical symptoms because the lateral ventricle has a relatively large compensating space. The most common initial symptoms are headaches, vomiting and consciousness disturbance related to increased intracranial pressure. Sensori-motor deficits, clumsiness, ataxia, and cognitive impairment including dysphasia, dyslexia, dysgraphia, and dyscalcula, are sometimes observed according to the tumor location. Visual field deficits and seizures are present, especially in patients with large tumors. Other unusual symptoms, such as epilepsy, can also occur [6]. Cushing and Eisenhardt grouped the symptoms caused by large ventricular meningiomas into the following types [7]: (a) headache caused by increased intracranial pressure; (b) contralateral spotted homonymous hemianopsia; (c) contralateral sensory disturbance and hemiparesis; (d) symptoms of cerebellar damage; and (e) possible paralexia in patients with tumors located on the left side.