• Mayo Clinic Minute: How gamma knife surgery treats brain tumors

It's a form of brain surgery without any incisions. Patients with brain tumors, both benign and malignant; vascular formations; and trigeminal neuralgia, a chronic condition that affects the nerve that carries sensation from your face to your brain often are candidates for a noninvasive procedure called gamma knife stereotactic radiosurgery. It pinpoints high doses of radiation at the tumor with little impact to surrounding healthy tissue.

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It's called gamma knife surgery, but there's no cutting involved.

"Gamma knife radiosurgery is the precise delivery of radiation to some imaging-defined target so we're able to treat benign or malignant tumors within the brain," says Dr. Bruce Pollock, a Mayo Clinic neurologic surgeon.

It's been used at Mayo Clinic for 30 years as an alternative to open brain surgery.

"We're performing an outpatient-based procedure that doesn't require an incision and has no risks of infections," says Dr. Pollock.

The patient's head is held still during the procedure with a headframe, which also serves as a map for the radiation. Using 3D imaging — typically an MRI — as a guide, the gamma knife is targeted directly at the tumor.

"The mechanical accuracy of the device is measured as a fraction of a millimeter," says Dr. Pollock.

And with no hospital stay and minimal side effects, it's a procedure that is efficient and can be lifesaving.

"For malignant tumors, the success rate per tumor typically is on the order of 90% or more. For benign tumors that are well-selected, the success rate really ranges up to about 95% to 97%," says Dr. Pollock.