Tumor Neurosurgery (eBook)

Investigations.- Neurophysiology.- Neuroradiology and Ultrasound.- Neuropathology.- Perioperative Care.- Neuroanesthesia.- Neurosurgical Intensive Care.- Techniques.- Neuroendoscopy.- Principles and Practice of Image-guided Neurosurgery.- Stereotactic Radiosurgery.- Tumors.- Low-grade Gliomasin Adults.- Neurosurgical Management of High-grade Gliomas.- Sellar and Parasellar Tumors.- Meningiomas.- Intraventricular and Pineal Region Tumors.- Cerebello-pontine Angle Tumors.- Skull Base Tumors.- Tumors: Cerebral Metastases and Lymphoma.- Pediatric Neuro-oncology.- Management of Spinal Tumors.- Management of Extradural Spinal Tumors.

"13 Intraventricular and Pineal Region Tumors (S. 235-236)

Sandeep Kunwar, G. Evren Keles, Mitchell S. Berger

Summary

Intraventricular and pineal region tumors represent 2% of all primary central nervous system tumors but have many unique features. Because many patients present with symptomatic hydrocephalus, urgent treatment of the tumor or hydrocephalus is often needed. Both benign and malignant tumors can arise in these regions, and often radiographic imaging is non-diagnostic. Surgery remains the main therapeutic approach for these tumors but is complicated by the central location of these lesions. A successful resection of intraventricular and pineal region tumors is based on a thorough knowledge of the relevant cerebral anatomy and the deep vascular system, avoidance of func ­tionally eloquent areas and use of limited retraction.

Intraventricular Tumors

Brain tumors located in the ventricles constitute 1.4% of all primary central nervous system tumors, and 5.4% of all central nervous tumors in the pediatric age group [1]. The most common primary neoplasms of the third ventricle are neuroepithelial tumors [2]. These tumors include juvenile pilocytic astrocytoma, astrocytoma, subependymal giant cell astrocytoma, ependymoma and glioblastoma multiforme. Although juvenile pilocytic astrocytomas most often originate from the floor of the third ventricle, they may arise from the posterior pituitary or optic system and extend into the ventricle. Low-grade astrocytomas, as well as anaplastic astrocytoma and glioblastoma multiforme, typically originate from the thalamic region. Ependymomas, and less frequently subependymomas, originate from the ventricular wall.

These lesions are more common in the lateral ventricles. Subependymal giant cell astrocytoma, which may be associated with tuberous sclerosis, often originates at the foramen ofMonro and is more frequently seen in the lateral ventricle. Colloid cysts are the most common lesions located in the third ventricle [3]. Although rare, epidermoid and dermoid tumors may occur in the third ventricle, and usually are solid rather than cystic at th is location. Meningiomas originating from the velum interpositum and choroid plexus papillomas are also seen in the third ventricle. Craniopharyngioma and suprasellar germinomas can invade the floor of the third ventricle.

Another main group of tumors that may grow into the third ventricle originate from the pineal gland and will be discussed in detail later in th is chapter. In addition to these primary neoplasms, metastatic tumors may occur in the third ventricle and invade its floor or lateral walls. Regarding lateral ventricle tumors, in a study excluding tumors that orig inated in the brain parenchyma with secondary extension into the ventricles, the authors found that the most common histologic diagnosis in adults was astrocytoma, followed by meningioma [2]. In the pediatric age group, the most common diagnosis was subependymal giant cell astrocytoma. In another series [4], the most frequent tumor types were subependymal giant cell astrocytoma, choroid plexus tumors, ependymoma and astrocytoma.

The most common location for lateral ventricular tumors was the trigone (38%), followed by the cella media (33%) and the frontal horn (27%) [2]. Intraventricular meningioma, although rare, is a well circumscribed tumor, most often located in the trigone, and constitutes approximately 0.5-2% of all intracranial meningiomas [3] (Figure 13.1). Approximately 80% occur in the lateral ventricles, more commonly in the left trigone, but can occur in the third ventricle, and less frequently in the fourth ventricle. Most patients present in the fourth to the sixth decades, and these tumors are more common in women.

The intraventricular location of these slow-growing tumors provides a compensatory mechanism in the form of reserve space, which contributes to the delay in clinical demonstration of symptoms and signs. They may either arise from the choroid plexus and grow with in the ventricle, or arise from the tela choroidea and grow partly within the ventricle and partly into the surrounding brain tissue . Imaging characteristics are similar to those of other meningiomas, being sharply defined and globular."