Neurosurgical tumors

A glioma (from the Greek “glia” = glue) is a collective term for brain tumors of the central nervous system that arise from glial cells, the supportive and nourishing tissue of nerve cells. They usually occur in the brain, but can also develop in the spinal cord and the optic nerve—which is considered part of the brain. They do not occur in peripheral nerves, because these do not contain glial cells.

A distinction is made between low-grade gliomas (WHO grades I and II) and high-grade gliomas (WHO grades III and IV).

Since gliomas are usually infiltrating tumors, they generally cannot be removed completely (in toto). Therefore, recurrences often develop, usually at the same location as the primary tumor.

Gliomas include:

• Astrocytomas
• Glioblastomas
• Oligodendrogliomas
• Oligoastrocytomas
• Ependymomas

Brain metastases are an important differential diagnosis when multiple intracranial lesions are detected and account for more than 60% of all brain tumors overall.

Brain metastases originate in another organ and arise when tumor cells from this primary tumor spread and form secondary deposits in the brain. These migrating tumor cells reach the brain via the bloodstream.

The brain is one of the preferred organs for the spread of solid tumors. Due to the frequency of the underlying cancers, 40–60% of brain metastases originate from bronchial carcinoma (lung cancer), 15–20% from breast carcinoma, and 10–15% from malignant melanoma (black skin cancer). In 10–20% of cases, the primary tumor remains unknown.

Therapeutic options:

• Surgical resection followed by radiation therapy, often in the form of targeted postoperative irradiation, for example using the Gamma Knife.
• Primary radiosurgery of one or multiple lesions using local, highly focused radiation (Gamma Knife radiosurgery); this is a treatment option when the metastases are smaller than 3 cm.
• Drug therapy, depending on the type of primary tumor and with adequate central nervous system (CNS) penetration.

• Primary CNS lymphomas
• Cysts: dermoid and epidermoid cysts; 0.3–1% of all brain tumors
• Tumors of the posterior cranial fossa: Hemangioblastomas, Medulloblastomas, Pilocytic astrocytomas, Ependymomas, Choroid plexus papilloma, PNET (Primitive Neuroectodermal Tumors)

Meningiomas, also known as tumors of the meninges, are very slow-growing and usually benign tumors of the meninges (the membranes covering the brain). They account for about 20–30% of all intracranial tumors.

They arise from the degeneration of cells of the arachnoid (one of the meningeal layers), which can lead to compression of adjacent brain tissue. Since they usually grow by displacement rather than infiltration, meningiomas can often be treated by complete surgical excision, but also by stereotactic radiosurgery and, in some cases, radiation therapy.

According to the WHO classification, meningiomas are divided into:

• Grade I meningioma (benign, 90–95%)
• Grade II meningioma – atypical meningioma (faster growth, more frequent recurrences, 5–8%)
• Grade III meningioma – anaplastic meningioma (malignant, infiltrative growth, tendency toward extracranial metastasis)

Schwannomas of the vestibular nerve (vestibular schwannomas) are benign tumors (WHO grade I) that are typically located in the cerebellopontine angle. They account for about 10% of all intracranial tumors, but approximately 80% of tumors of the cerebellopontine angle.

The tumor originates in the internal auditory canal and grows toward the cerebellum. The facial nerve is variably displaced and is usually adherent to the surface of the tumor. An early symptom of the growing tumor, which compresses the auditory nerve, is slowly progressive hearing loss in one ear (hence the historical term acoustic neuroma). Vestibular schwannomas occur predominantly in middle age and grow very slowly, at a rate of approximately 0.1–0.2 cm per year.

From a therapeutic perspective, surgical removal is generally recommended. However, in the case of smaller tumors, high-dose radiation therapy (Gamma Knife radiosurgery) may be used as the primary treatment, or a “wait-and-see” strategy with regular MRI monitoring may be chosen.

To determine the most appropriate therapy and to better estimate the risk of potential postoperative loss of cranial nerve function—particularly of the acoustic nerve or facial nerve—the Koos classification is often considered. This anatomical classification system for vestibular schwannomas is named after Wolfgang Koos, who served as head of the Vienna University Department of Neurosurgery (1978–1998).

Koos, Wolfgang T., et al. Neurotopographic considerations in the microsurgical treatment of small acoustic neurinomas. Journal of Neurosurgery 88.3 (1998): 506–512.

The pituitary gland, also called the hypophysis, is located in a bony depression behind the nose and beneath the brain, known as the sella turcica, and is responsible for regulating the secretion of many important hormones. Pituitary tumors are generally benign, slow-growing tumors originating from the anterior pituitary lobe. They are classified into hormonally inactive and hormonally active tumors, and further categorized by size into microadenomas and macroadenomas (≥10 mm), i.e., small and large tumors.

In hormonally active tumors, there is excessive secretion of one or more hormones, leading to various clinical manifestations. Examples include: Cushing’s disease – overproduction of ACTH (adrenocorticotropic hormone), Acromegaly – increased secretion of STH (growth hormone or somatotropic hormone), Prolactinoma – pituitary tumor producing prolactin.

Surgical intervention (pituitary surgery) for a pituitary adenoma is usually indicated in the presence of: A chiasma syndrome (compression of the optic chiasm by a large tumor), excessive hormone secretion or anterior pituitary insufficiency caused by pressure of a large tumor on the healthy pituitary tissue. Prolactinomas are the only adenomas treated primarily with medication.

At our clinic, the interdisciplinary Pituitary Board discusses treatment strategies, disease progression, and complex pathologies in the sellar region.