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Pineocytoma (WHO grade I), pineal parenchymal tumor of intermediate differentiation (WHO grades II and III), pineoblastoma (WHO grade IV), and papillary tumor of the pineal region are tumors affecting the pineal region. These tumors are rare and can affect persons of all ages.

This chapter deals with tumours whose origin is from intracerebral cells. They include a whole family of tumours of which the commonest are the gliomas. However, the list includes ependymomas, haemangioblastomas and others. The chapter sections will be grouped according to the cell of origin of the tumours being considered. Clinical presentations will not be presented since they are to be found in any standard neurosurgery textbook. The questions to be examined here are the suitability of GKNS as a treatment once the diagnosis is established. Since the role of the treatment is in fact in debate for all the indications mentioned in this chapter, the subject matter will be limited to the commoner disease processes concerning which there is some degree of useful documentation. Moreover, it should be mentioned that stereotactic fractionated treatments are in use and their role is being assessed. They are however not included in this chapter being considered outside the scope of this book.

Pineal region tumors include a variety of neoplasms of different histological origin growing from the pineal gland itself or from structures of the parapineal space. These tumors are rare and account for 0.4 to 1.0% of intracranial tumors in adults and 3.0–8% in children. The most common types are germ cell tumors, pineal parenchymal cell tumors and glial cell tumor. Other pineal region tumors such as meningiomas, PNET, neurocytomas, hemangioblastomas, cavernomas and metastasis are infrequent.

A variety of tumours arise in the pineal region [44]. Germ cell tumours (GCTs), which is a heterogeneous group of various neoplasms, is the most common type, followed by pineal parenchymal cell tumours, pine-ocytomas and pineoblastomas. Planning of surgical management depends on the biological nature of individual neoplasms and is determined by preoperative radiological findings and an intraoperative histological diagnosis using frozen sections, as well as the surgeon’s experience. Germinoma, which is the most common tumour originating from the pineal body, can be cured by low-dose radiotherapy and chemotherapy, and nowadays needs only to be biopsied. On the other hand, mature teratomas, dermoid or epidermoid cysts, neurocytomas, and meningiomas can be cured by radical surgical resection. Pineal parenchymal tumours and ependymomas require surgical removal and adjuvant radiotherapy. Other tumours, such as malignant teratomas or embryonal carcinomas, need a sophisticated combination therapy including surgery, radiation therapy, and chemotherapy. For such tumours, neurosurgeons should recognize that a surgical resection is only a part of the combination therapy. For instance, application of an appropriate neoadjuvant therapy prior to a radical surgical removal will remarkably reduce the surgical risk for the patients with large malignant pineal tumours.

Central nervous system (CNS) germ cell tumors (GCT) are rare neoplasms primarily occurring in adolescent and pediatric populations. The age-adjusted incidence rate in the United States is 0.1 per 100,000 person-years. These GCT are, however, more common in far-east Asia than in western countries. The incidences in the United States and Japan account for 0.5% and 3.1% of all primary brain tumors, respectively (CBTRUS 1996, JBTR 1996).

Central nervous system (CNS) germ cell tumors (GCTs) exhibit diverse neurological signs and symptoms. It is clear that the neurological manifestations of CNS GCTs are totally dependent on the site of the tumor origin. A pineal region mass causes symptoms of increased intracranial pressure and impairment of ocular movement. A hypothalamic-neurohypophyseal mass induces a variety of neuroendocrinological problems, as well as neurocognitive and visual disturbances. Currently, a vast majority of CNS GCT are curable neoplasm, though thay are malignant in nature, and many of neurological deficits at diagnosis are irreversible even after successful treatment for a tumor. An earlier diagnosis by a physician, Which can provide a better prognosis for patients is extremely important.

Intracranial cavernous vascular malformations are variously known as cavernous angiomas, cavernous hemangiomas or, more simply, cavernomas.

The tumors originating in this site make up a heterogeneous group of neoplasms and account for approximately 1% of all intracranial tumors. Some derive from the parenchymal cells of the pineal gland: pineocytoma and pineoblastoma; others originate from the supporting tissues: tumors of glial origin; additionally, with greater incidence, others may originate from embryonic cell nests which do not belong to the pineal gland: germinomas and teratomas. In this site, papillomas of the choroid plexus and meningiomas are less frequent. Nontumoral space-occupying processes of the pineal gland, mostly arachnoid and parasitic cysts, will be discussed in a separate chapter.

Following an introductory chapter which presents the scientific basis of the complex phenomenon of nuclear magnetic resonance and MR imaging, this study explores MR anatomy of the brain and the classification of tumours of the central nervous system. Further essays deal with one of the following: neuroepithelial tumours, pineal region tumours, meningiomas, neurinomas, pituitary adenomas and craniopharyngiomas, angiomas and aneurysms producing mass effect, intracranial metastatic tumours, rare tumours, expansive nontumoural lesions and spinal tumours. There is a brief clinical discussion on each of these topics, and each chapter is illustrated with reproductions of MR images of these lesions.

Personal experience with surgical exploration and total resection or evacuation of pineal and midbrain mass lesions in 20 pediatric patients from a total material of 52 cases demonstrate the efficacy of modern microsurgical techniques. Microtopography indicated the choice of the most suitable approach to these deep-seated lesions. The infratentorial supracerebellar approach proved to be the ideal exposure, except in one case of a lesion in the interpeduncular cistern, where a subtemporal approach was chosen. There was only one death as a consequence of the operation in a case of an extensive medulloblastoma; in all the other cases, no increase in morbidity occurred after surgery. Duration of post-operative observation with individual survival times will be demonstrated.

We have now operated and confirmed 80 tumors of the pineal region. Our experience is that 30 percent of these are benign, encapsulated and can be removed, and that only 30 percent represent germinomas. Another 30 percent are astrocytomas of varying grade. The preferred therapy in the majority of these tumors is radiotherapy and its extent depends upon the analysis of the lumbar spinal fluid. Chemotherapy has been reserved for tumors of the primitive embryonic type.

The treatment of tumors in the pineal area remains controversial. There are two main approaches

The idea of organizing a Symposium on Stereotactic Cerebral Irradiations arose from several converging trends in the recent evolution of stereotactic neurosurgery. The latter might indeed offer solutions to problems arising from significant progress achieved in other fields.

On the basis of anatomical studies in fresh cadavers, formalin fixed brains and clinical experiences in 40 surgically treated cases of pineal and midbrain lesions the most important surgical approaches with their anatomical peculiarities as well as pitfalls are demonstrated. Emphasis is given to the great vein of Galen and its tributaries as major obstacle in microsurgery in this area.

The use of the operating microscope and specialized anesthesiologic techniques make it possible to operate safely on tumors in the pineal region. A survey is presented of the main surgical and anesthesiologic techniques used: the supracerebellar infratentorial approach in the sitting position and the occipital transtentorial approach in the semi-sitting position. For selecting the optimal approach a CT scan with sagittal sections is very important to localize the tumor in relation to the tentorium cerebelh, the straight sinus and the great vein of Galen. Based upon the comparison of the two techniques the author concludes that nearly all tumors in the pineal region in children can be operated by the infratentorial supracerebellar route and that the transtentorial route offers relatively little advantage.