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Definition
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| Stereotactic radiosurgery (SRS) is a way of treating brain disorders with a precise delivery of a single high dose of radiation in a one-day session. Treatment involves the use of focused radiation beams delivered to a specific area of the brain to treat abnormalities, tumors or other functional disorders. Fractionated stereotactic radiation treatments - which are received over a period of days or weeks - may be administered in the body with the assistance of removable masks and frames that achieve some degree of lesser mobilization. Stereotactic radiosurgery is primarily limited to the head and neck as these areas can be immobilized with skeletal fixation devices that completely restrict the head's movement , permitting the most precise and accurate treatment. Treatment without a skeletal fixation device for a one-session treatment is not recommended because of the high potential for damage to healthy brain tissue, cranial nerves (optic, hearing, etc.) and the brain stem. |
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| Surgery |
| Radiosurgery (one-session treatment) has such a dramatic effect in the target zone that the changes are considered "surgical." Through the use of three-dimensional computer-aided planning and the high degree of immobilization, the treatment can minimize the amount of radiation to healthy brain tissue. Stereotactic radiosurgery is routinely used for brain tumors and lesions. It may be the primary treatment; utilized where a tumor is inaccessible by surgical means; or as a boost or adjunct to other treatments with a recurring or malignant tumor. In some cases, it may be inappropriate. |
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| How it Works |
 Stereotactic radiosurgery works the same as all other forms of radiation treatment. It does not remove the tumor or lesion, but it distorts the DNA of the tumor cells. The cells then lose their ability to reproduce and retain fluids. The tumor reduction occurs at the rate of the normal growth rate of the specific tumor cell. In lesions such as AVMs (a tangle of blood vessels in the brain), radiosurgery causes the blood vessels to thicken and close off. The shrinking of a tumor or closing off of a vessel occurs over a period of time. For benign tumors and vessels, this will usually be 18 months to two years. For malignant tumors and metastatic tumors, results may be seen as soon as a couple of months as these cells are very fast-growing. |
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| Side Effects |
| Swelling : As with all radiation treatments, the cells of the irradiated tumors lose their ability to regulate fluids and edema or swelling may occur. This does not happen in all treatments. If swelling does occur, and it causes symptoms that are unpleasant, then a mild course of steroid medication may be given to reduce the fluid within the tumor cavity. |
| Necrosis: The tumor tissue that remains after the radiation treatment will typically shrink. On rare occasions this necrotic or dead tissue can cause further problems and may require removal. This occurs in a very small percentage of cases. |
| Other Effects: Other side effects may occur dependent upon the site of targeting and the dosage of radiation received. This should be discussed throughly with your treating physician. For more information on side effects and radiation injury Click Here. |
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| Appropriate? |
Because all forms of radiation treatments work over time, they may be inappropriate if symptoms are severe or life-threatening. Relief of acute symptoms may drive the first treatment choice to open skull surgery or medication. For instance, if current symptoms when diagnosed are so severe that quality of life is affected the appropriate choice for the first treatment may be surgery to relieve those symptoms. The secondary treatment could then be radiosurgery.
In other cases where cells are extremely fast growing (with or without severe symptoms), such as in brain metastases, radiosurgery can quickly control the brain tumors to allow time to treat the primary cancer site. Medication can be given for the side effects of edema and radiation therapy may be used over a period of time to help eliminate the stray cancer cells from the brain. |
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| Previous Radiation |
| Stereotactic radiosurgery can be used in patients who have failed standard radiation techniques or in patients who have already received the maximum radiation dose permissible or whole brain radiation. At this time, there are no known cases of radiation-induced new tumors from stereotactic radiosurgery in 30 years of treatments. This may be attributed to the preciseness of the treatment and the sparing of healthy nerves and tissues. A patient who has had stereotactic radiosurgery for a brain tumor or condition may later have open skull surgery without problems. In many cases, if necessary, additional treatments of stereotactic radiosurgery can be performed. |
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| Indications |
| Stereotactic radiosurgery may or may not be appropriate for a condition. It may be used as the primary treatment or recommended in addition to other treatments that are needed. Only a treating neurosurgeon who operates radiosurgery equipment can make the evaluation as to whether someone can be treated. A neurosurgeon must always be present during treatment and should work with a radiation oncologist when the brain is being targeted. Some of the most common indications for treatment are: |
 Arteriovenous malformations |
| All benign brain tumors including: |
 Acoustic Neuromas |
| Meningiomas |
| Pineal and Pituitary |
| All malignant brain tumors including: |
| Glial and astrocytomas |
| Low grade tumors |
| Metastatic brain tumors |
| Functional disorders including: |
| Trigeminal Neuralgia |
| Essential Tremor |
| Parkinson's Tremor/Rigidity |
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