Gamma Knife for AVM @ Wake Forest (3)

The Gamma Knife has revolutionized the treatment of brain metastases from once difficult to treat tumors such as melanoma, kidney cancer, lung cancer, and breast cancer.

It offers extraordinarily high rates of local control (nearly 90% in most studies) of these tumors when deposits have begun to grow in the brain.

It's becoming clear that this is the treatment of choice for multiple brain metastases. There is a significant chance that Gamma Knife radiosurgery can eliminate brain metastases as a cause of death in a cancer patient afflicted with this problem. A recent randomized study demonstrates a six-fold benefit of the Gamma Knife in treating people with multiple brain metastases over whole brain radiation alone. Furthermore, a study conducted by the Radiation Therapy Oncology Group (RTOG) found people with recurrent brain tumors treated with Gamma Knife radiosurgery are almost three times more likely to have success than those treated with linear accelerator radiosurgery.

It can be used in addition to whole brain radiation therapy. It also has the potential to allow people to avoid or delay whole brain radiation sparing them from its side effects such as hair and memory loss and dementia.

While the benefits of Gamma Knife have been proven for up to four lesions there is no arbitrary limit to the number of lesions that can be treated successfully. Large lesions and some of those that are producing symptoms from swelling may still benefit from convential surgery. Any additional lesions can then be treated with the Gamma Knife. Close follow up after surgery and Gamma Knife radiosurgery is usally warranted so that any new lesions can also be treated. Multiple treatments can be employed when necessary but are not usually needed.

The 22-ton Gamma Knife unit aims 201 "pencil beams" of radioactive cobalt-60 at the target brain tissue, sharply focused to minimize radiation effects to surrounding healthy brain tissues. Using computers, a team of neurosurgeons, radiation oncologists and radiation physicists precisely conform the radiation dose to the size and shape of the lesion.

In a typical scenario, both the neurosurgeon and radiation oncologist evaluate patients (along with prior imaging studies and records) to determine if they are appropriate candidates for the procedure. On the morning of the procedure, a mechanical guiding device called a stereotactic head frame is attached to the patient's head. The location of the tumor and the surrounding normal tissue is evaluated with imaging technology such as computed tomography (CT), angiography, and/or magnetic resonance imaging (MRI). Next, the team of neurosurgeons, radiation oncologists and radiation physicists works together to plan the Gamma Knife procedure so it precisely treats the target lesion.

Drs. Stephen Tatter and Edward Shaw prepare a patient for Gamma Knife radiosurgery.

The patient's head is then placed into the Gamma Knife, a large helmet-like device with 201 openings that focus the narrowbeams of radiation onto the target in the brain. The dose of radiation each patient receives is selected by the neurosurgeon and radiation oncologist depending on the type and location of each lesion. The radiation treatment session usually lasts 30 to 60 minutes, and up to several hours for very complex cases. Following the completion of radiosurgery, the head frame is removed and the patient is sent home with only two bandaids on the forehead to show for the entire procedure.

Gamma Knife treatment causes few of the immediate side effects that are associated with conventional external beam radiation. Fatigue, hair loss, nausea, vomiting and headaches rarely occur; and few infections, hemorrhages or other standard neurological complications have been reported as a result of Gamma Knife procedures. Patients usually return home the same day and return to their normal schedule within a day or so.

While traditional surgery may deliver more immediate results, the gamma knife’s long-term prognosis is often comparable or better. In most cases, gamma knife radiosurgery immediately stops the growth of tumors, which shrink or disappear over a period of time.

Gamma knife treatment offers some patients the ability to maintain or improve quality of life, says neurosurgeon Charles Branch, M.D. "People with lesions that were considered inoperable or with health issues that made them poor candidates for open surgery are good candidates for this procedure. It is especially useful when conventional surgical techniques would pose a high risk, such as in the presence of other illnesses or when a patient’s age prohibits standard surgery."

Radiation oncologist Edward Shaw, M.D., co-director of the Gamma Knife Program, calls gamma knife "one of the most exciting and potentially beneficial medical technologies available today."

A Brief History

The first gamma knife radiosurgery unit was developed in Sweden in 1967 to treat functional neurological disorders such as Parkinson’s disease, trigeminal neuralgia (severe facial pain) and essential tremor. The technology has been refined and perfected over three decades. Gamma knife radiosurgery is now an approved treatment for selected benign and malignant brain tumors and vascular malformations.

Wake Forest University Baptist Medical Center is home to North Carolina’s only Gamma Knife Radio-surgery Program. The Medical Center’s program in neurology and neurosurgery is among the top 20 in the nation according to a U.S.News & World Report ranking.

Some of the most common indications for Gamma Knife treatment include:

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010707 Stephen B. Tatter, M.D., Ph.D.