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Brain Tumors

 

 

Related narratives: Astrocytoma, Astrocytoma and Neurofibromatosis

Tumors of the nervous system constitute 10% of all neoplasms in adults, and up to 20% in children. Most adult tumors are supratentorial while those of childhood are below the tentorium. Seventy-five percent of intracranial tumors in adults are malignant. The percent decreases in the elderly as meningiomas and Schwannomas become more common.

Intracranial tumors produce symptoms by a combination of irritation, tissue destruction and compression within the closed space of the cranial vault. Irritation results in focal seizures. Compression may produce focal neurological deficits. The increased intracranial pressure generated by the expanding mass causes generalized effects such as headache, nausea and vomiting, decreased consciousness and decreased cognitive functions and may lead to hydrocephalus, hemorrhage and cerebral edema.

The great majority of tumors arising within the brain parenchyma are derived from the supporting glial (glia=glue, L) cells. The principle types of glial cells are astrocytes, oligodendrocytes and ependymal cells. Malignancy of gliomas is not judged by metastatic potential, which is blocked by the blood brain barrier and lack of lymphatics in the brain. Histological grading (1-4) correlates with rate of growth and infiltration of surrounding tissue. Grading is based on cellularity, mitoses, endothelial proliferation and necrosis. Grade 1 lesions have distinct boundaries and are considered to have no potential to transform into a higher grade. Low grade astrocytomas (grade 2) have one histological characteristic, are less well demarcated, grow slowly, but may degenerate into a higher grade lesion. Anaplastic (grade 3) lesions have two of the negative histological features and grow more rapidly. The highest grade (4) are called glioblastoma multiforme, are the most aggressive, and also the most common. The older the patient, the more advanced the grade is likely to be. The growth tends to follow white matter tracts and the lesion may cross the corpus callosum (butterfly lesion).

Low grade lesions presenting with slowly progressive symptoms over a long (1-2 years) period are treated with surgical debulking. Complete resection is usually not possible because of the infiltrative nature of the lesion. There is some support for use of radiotherapy, but no demonstrated benefit of chemotherapy. Median survival is 5-7 years. High grade astrocytoma presents with a more acute onset, and is best treated with surgical resection and fractionated external beam radiation. Chemotherapy has some role in extending survival and quality of life, and may be the final recourse for recurrence. The completeness of the resection, younger age and good performance status correlate with a better outcome. Median survival time for anaplastic is two years, and for glioblastoma one year.

References:

Aldrich EF, Chin LS, DiPatri A, Eisenberg HM. Primary brain tumors, in Townsend: Sabiston Textbook of Surgery, 16th ed., Copyright 2001 W. B. Saunders Company, 1518-1526.

Hoff JT, Harrigan MR. in Greenfield LJ, Surgery (3rd ed), Lippincott, Williams & Wilkins, Phila, 2001: 2149-2150.


This page was last modified on 14-Aug-2002.