Stereotactic Radiosurgery Health Article

Definition

Stereotactic radiosurgery is the use of a precise beam of radiation to destroy tissue in the brain.

Purpose

This procedure is used to treat brain tumors, arteriovenous malformations in the brain, and in some cases, benign eye tumors or other disorders within the brain.

Demographics

Stereotactic radiosurgery is used to treat a variety of disorders with widely differing demographic profiles.

Description

"Radiosurgery" refers to the use of a high-energy beam of radiation. "Stereotactic" refers to the three-dimensional targeting system used to deliver the beam to the precise location desired. Stereotactic radiosurgery is primarily confined to the head and neck, because the patient must be kept completely still during the delivery of the radiation in order to prevent damage to surrounding tissue. The motion of the patient's head and neck are restricted by a stereotactic frame that holds them in place. It is difficult to immobilize other body regions in this way.

The high energy of the radiation beam disrupts the DNA of the targeted cells, killing them. Multiple weak beams are focused on the target area, delivering maximum energy to it while keeping surrounding tissue safe. Since the radiation passes through the skull to its target, there is no need to cut open the skull to perform the surgery. The beam can be focused on any structure in the brain, allowing access to tumors or malformed blood vessels that cannot be reached by open-skull surgery.

Two major forms of stereotactic radiosurgery are in use as of 2003. The Gamma Knife^® is a stationary machine that is most useful for small tumors, blood vessels, or similar targets. Because it does not move, it can deliver a small, highly localized and precise beam of radiation. Gamma knife treatment is done all at once in a single hospital stay. The second type of radiosurgery uses a movable linear accelerator-based machine that is preferred for larger tumors. This treatment is delivered in several small doses given over several weeks. Radiosurgery that is performed with divided doses is known as fractionated radiosurgery. The total dose of radiation is higher with a linear accelerator-based machine than with gamma knife treatment.

Disorders treated by stereotactic radiosurgery include:

• benign brain tumors, including acoustic neuromas and meningiomas
• malignant brain tumors, including gliomas and astrocytomas
• metastatic brain tumors
• trigeminal neuralgia
• Parkinson's disease
• essential tremor
• arteriovenous malformations
• pituitary tumors