What is gamma knife surgery?

Gamma knife surgery is a type of radiation treatment performed with the Gamma Knife®, a noninvasive neurosurgical tool. Gamma knife surgery involves focusing small, highly precise doses of radiation into the brain. This shrinks small brain tumors or blocks abnormal blood vessels and nerves that cause pain or seizures. Gamma knife surgery can also treat some brain disorders, such as Parkinson’s disease.

Gamma knife surgery does not actually involve a knife or surgery. The name is derived from the knife-like precision of the radiation delivered to the target area. Gamma knife surgery is also called gamma knife radiosurgery or stereotactic radiosurgery. 

Gamma knife surgery is an effective alternative to neurosurgery for some patients. Gamma knife surgery can help if you cannot tolerate neurosurgery because of your medical condition, age, or preference. It is less invasive and requires less hospitalization and recovery time than neurosurgery. Discuss all the procedure and surgery options with your doctor and consider getting a second opinion about all of your treatment choices before having gamma knife surgery.

Why is gamma knife surgery performed? 

Your doctor may recommend gamma knife surgery to treat some diseases and conditions of the brain. Ask your doctor about all of your treatment options and consider getting a second opinion before deciding on gamma knife surgery.

Your doctor may recommend gamma knife surgery to treat:

  • Acoustic neuroma, a tumor of the nerve between the brain and the ear
  • Arteriovenous malformations (AVMs) and other blood vessel disorders in the brain
  • Brain tumors including some types of malignant and benign tumors
  • Some types of cancer of the eye
  • Epilepsy caused by a brain tumor. A brain tumor that causes epilepsy may be treated with gamma knife surgery if medications do not control seizures.
  • Parkinson’s disease, a brain disorder that leads to uncontrollable shaking, muscle stiffness, and severe problems with coordination and balance
  • Trigeminal neuralgia, a nerve disorder causing debilitating face pain

Who performs gamma knife surgery?

A specialized team performs gamma knife surgery. These teams commonly include the following specialists:

  • Medical physicists are scientists who specialize in the safety and effectiveness of radiation treatments and imaging procedures.
  • Neurosurgeons and pediatric neurosurgeons specialize in the surgical treatment of diseases of the brain, spinal cord, and nerves.
  • Radiation oncologists specialize in treating cancer with radiation. 

Teams may also include one or more of these specialists depending on your diagnosis:

  • Otolaryngologists, or ear, nose and throat (ENT) doctors, specialize in the medical and surgical care of the ears, nose and throat, and conditions affecting the head and neck.
  • Neuroradiologists specialize in diagnosing and treating diseases of the nervous system using radiological imaging.
  • Neurotologists specialize in the medical and surgical care of diseases of the inner ear and related structures. They are sometimes called otologists or otologists/neurotologists.

How is gamma knife surgery performed?

Your gamma knife will be performed in a hospital. The entire process occurs during a single day and generally includes these steps:

  1. You will dress in a patient gown and remove any jewelry, wigs, glasses or any other items that may interfere with the radiation treatment.
  2. A treatment team member will start an intravenous (IV) line. You will receive fluids and a mild sedative or other medications during the procedure.
  3. You will have four small injections of local anesthetic to numb the area in your scalp. 
  4. Your care team will attach a head frame to your head with pins at the site of the anesthetic injections. They will not need to shave your hair to do this. Some people report a feeling of pressure when they are fitted with a head frame, but it usually goes away within a few moments.
  5. The treatment team will take brain imaging scans (pictures) to precisely locate your tumor or target area. The scan might be a magnetic resonance imaging scan (MRI), a computed tomography scan (CT), a cerebral angiogram, or a combination of these. 
  6. You will wait in a separate room while your care team determines the exact treatment plan and where to apply the radiation.
  7. You will return to the gamma knife treatment room and lie on a sliding bed. Your care team will fit a treatment helmet, called a collimator helmet, over your head frame. The helmet has a special pattern of holes in it. The holes will direct radiation beams to pass through to the exact location in your brain needing treatment.
  8. The bed will slide into the gamma knife machine. You might hear a clicking sound as the helmet attaches to the machine.
  9. Your care team will leave the treatment room, but they will observe you by video. You will be able to talk with them over an intercom.
  10. The radiation treatment itself takes from one to four hours, depending on your treatment plan. You will not feel the treatment while it is happening, and it does not produce any sounds or smells. Some people even fall asleep during treatment.
  11. When the radiation treatment is complete, your care team will return to the gamma knife treatment room. The team will slide your bed out of the treatment machine and remove your collimator helmet, head frame, and IV line. 
  12. Your care team will make sure that your vital signs, such as blood pressure and pulse, are stable. They will give you medication for nausea or head pain as needed. Most people who receive gamma knife surgery go home the same day. Some patients stay in the hospital for a night for further observation.