Intraventricular meningiomas of the lateral ventricle occur relatively rarely, but they are often large at the time of detection and present more commonly on the left side. Although the ability to resect these tumors safely has greatly improved over time, standard surgical approaches often traverse cortex close to areas of specific cortical function. Precise cortical mapping of language and sensorimotor cortices can be accomplished noninvasively by using functional magnetic resonance (fMR) imaging. The authors used fMR imaging in planning the cortical incision for resection of a large intraventricular trigone meningioma in the dominant hemisphere of a patient who, postoperatively, suffered no aphasia or hemiparesis. The authors discuss the advantages of mapping cortical function preoperatively with fMR imaging when approaching intraventricular lesions.
Since Cushing performed the first radical removal of a meningioma from the lateral ventricle in 1916, the surgical management of these lesions has been a difficult and challenging task for neurosurgeons. A variety of surgical approaches have been used to resect intraventricular meningiomas of the trigone, many of which require transcortical incisions that may be in proximity to eloquent cortex, including sensorimotor and language areas.
Functional MR imaging provides a noninvasive method for identifying human cortical function by using the BOLD technique. This technique is based on the paramagnetic quality of deoxyhemoglobin, which can indirectly reflect neuronal activation due to local changes in regional CBF. Functional MR imaging has been used in a wide variety of neurosurgical applications for the treatment of epilepsy, AVMs, and tumors.
In our case a meningioma at the trigone of the left lateral ventricle was successfully excised without causing permanent postoperative deficit. Presurgical fMR imaging allowed intraoperative identification of the most appropriate area for cortical incision and allowed us to preserve primary language and sensorimotor cortices. We believe that fMR imaging is a useful adjunct in the preoperative planning for resection of meningiomas of the lateral ventricles and that its role in neurosurgical applications of the future will expand.