Saint Joseph's, Atlanta - Gamma knife for Glioma

The most common type of primary brain tumor is a glioma. A glioma is a type of primary central nervous system tumor that arises from nerve cells known as glial cells, the supportive tissue of the brain. The most common site of involvement of a glioma is in the brain, but these tumors can also affect the spinal cord or any other part of the central nervous system. About 42% of all brain tumors, including benign ones, are gliomas. Counting only malignant tumors, 77% are gliomas. They are uncommon in children, but their incidence rate goes up with age and peaks in the age group from 75 – 84.

There are several types of gliomas. They are categorized according to where they are found and the type of cells from which the tumors originated. The following are different types of gliomas:

Astrocytomas are glial cell tumors that are derived from connective tissue cells called astrocytes. These cells can be found anywhere in the brain or spinal cord. Astrocytomas are the most common type of childhood brain tumor, and the most common type of primary brain tumor in adults. Astrocytomas are generally subdivided into high-grade or low-grade tumors. High-grade astrocytomas are the most malignant of all brain tumors. Astrocytomas are further classified for presenting signs, symptoms, treatment, and prognosis, based on the location of the tumor. Patients usually have symptoms of increased intracranial pressure, headache, and vomiting. There can also be problems with walking and coordination, as well as double vision. In adults, astrocytomas are more common in the cerebral hemispheres (cerebrum), where they commonly cause increased intracranial pressure (ICP), seizures, or changes in behavior.
Brain stem gliomas are tumors found in the brain stem. Most brain stem tumors cannot be surgically removed because of the remote location and delicate and complex function controlled by this area. Brain stem gliomas occur almost exclusively in children; the group most often affected is the school-age child. The child usually does not have increased intracranial pressure (ICP), but may have problems with double vision, movement of the face or one side of the body, or difficulty with walking and coordination.
Ependymomas are also glial cell tumors. They usually develop in the lining of the ventricles or in the spinal cord. The most common place they are found in children is near the cerebellum. The tumor often blocks the flow of the CSF (cerebral spinal fluid, which bathes the brain and spinal cord), causing increased intracranial pressure. This type of tumor mostly occurs in children younger than 10 years of age. Ependymomas can be slow growing compared to other brain tumors but may recur after treatment is completed. Recurrence of ependymomas results in a more invasive tumor with more resistance to treatment.
Optic nerve gliomas are found in or around the nerves that send messages from the eyes to the brain. They are frequently found in patients who have neurofibromatosis, a hereditary condition that makes a person more likely to develop tumors in the brain. Patients usually experience loss of vision, as well as hormone problems, since these tumors are usually located at the base of the brain where hormonal control is located. These tumors are typically difficult to treat due to the surrounding sensitive brain structures.
Oligodendrogliomas also arise from the supporting cells of the brain. They are found commonly in the cerebral hemispheres (cerebrum). Seizures are a very common symptom of these tumors as well as headache, weakness, or changes in behavior or sleepiness. This tumor is more common in patients in their 40s and 50s. Oligodendrogliomas have a better prognosis than most other gliomas, but they can become more malignant with time.

Most brain tumors are not associated with any known risk factors and occur for no apparent reason. However, there are a few factors that may be associated with brain tumors. One such risk factor is prior radiation treatment generally given for the treatment of other cancers and usually given over a period of time. Other environmental factors have been suggested as possible risks, although there is no conclusive evidence that they indeed cause brain tumors. These factors include exposure to vinyl chloride (a gas used in the manufacture of plastics), exposure to aspartame (a sugar substitute), exposure to electromagnetic fields (such as from cellular telephones or high-tension wires), and previous injury to the head. Rare cases of brain and spinal cord tumors tend to run in families.

Progressive weakness, speech or visual loss, headaches, and seizures may result from the pressure of the tumor on critical structures nearby. Other symptoms may include difficulty thinking or speaking, behavioral or cognitive changes, weakness or paralysis in one part or side of the body, loss of balance, vision changes, and nausea or vomiting.

CT scans and MRI (with and without contrast) are helpful in the diagnosis, grading, and pathophysiological evaluation of gliomas. MRI is considered the criterion standard, but a CT scan may be useful in the acute setting or when MRI is contraindicated. Surgical biopsies are not always required for diagnosis of a glioma. With current scanning ability of CT and MRI scans, brain tumors may be diagnosed as malignant or benign without opening the skull for a biopsy.

Several different treatments may be used to treat gliomas. The decision for treatment is dependent upon many factors including the size of the tumor, its growth rate, and the symptoms produced by the tumor. In addition, the patient’s health and physical status may also affect the treatment process. Tumors may be treated with surgery, with chemotherapy, with radiation, or a combination of all of these.

Surgery is usually considered the first-line treatment. Many times partial removal of the tumor is attempted and the residual tumor treated by some other means. When surgery is required, the surgeon often uses a high-powered microscope to magnify the surgical field, or other technologies may be used to visualize the tumor during the surgery.

Radiation therapy is used to treat a majority of these tumors, often in conjunction with surgery and chemotherapy. Radiotherapy (or radiation therapy) is directed by a radiation oncologist using one of many types of linear accelerator machines. Radiation therapy is performed over a period of time allowing the normal cells time to heal from the radiation. Most times the treatment is divided into daily doses occurring over a period of several weeks. Radiation may be used to kill remaining tumor cells after surgery or for tumors that show a particular sensitivity to radiation. It can also be used to treat tumors that are too large to be treated with other forms of therapy.

Chemotherapy may also be used to treat gliomas in conjunction with surgery and radiation. Every year more research is performed to find the best drugs to treat malignant brain tumors. Promising results have been realized lately with the use of the chemotherapeutic agent known as Temodar.

Gamma Knife radiosurgery treatment may be used in addition to surgery, conventional radiation, and chemotherapy. When Gamma Knife treatment is selected, there are several advantages to this approach:

Over thirty years of world-wide research supports the effectiveness of Gamma Knife radiosurgery. The December 2000 and 2002 supplements to the Journal of Neurosurgery were devoted to neurosurgical stereotactic radiosurgery using the Gamma Knife. These editions (some full-text articles and all “abstracts” of articles) can be found on-line at www.thejns-net.org.

The Gamma Knife Center
Saint Joseph's Hospital
5665 Peachtree Dunwoody Road
Atlanta, Georgia 30342
404-851-5513
1-866-SJGAMMA (toll-free)

Several organizations provide information on glioblastomas and other malignant and benign brain tumors. Please contact the following for more information on this topic: