What is Gamma Knife radiosurgery?
Gamma Knife radiosurgery is a form of radiation therapy that accurately focuses hundreds of individual laser beams at a tumour. It is often used as an alternative therapy to chemotherapy, surgery or other forms of radiation oncology to treat brain tumours.
Why do you need Gamma Knife radiosurgery?
Gamma Knife radiosurgery can be used to treat the following conditions:
- Benign brain tumours
- Malignant brain tumours
- Nerve disorders, such as trigeminal neuralgia
- Arteriovenous malformations (AVMs), which is an abnormal collection of blood vessels
- Acoustic neuroma, a non-cancerous tumour that develops between your inner ear and brain.
- Pituitary tumours, which are tumours at the base of your brain (pituitary gland)
The effects of the Gamma Knife radiosurgery will not be immediate but gradual. As radiation treatments are designed to stop the growth of tumours or lesions, you may only see progress over a period of weeks or months.
Your doctor will stay in contact with you during this period. To track your progress, you may need follow-up magnetic resonance imaging (MRI) scans, computed tomography (CT) scans or angiography examinations.
Who should not do Gamma Knife radiosurgery?
If you are expecting, you should discuss with your doctor if you should go ahead with Gamma Knife radiosurgery.
What are the risks and complications of Gamma Knife radiosurgery?
Despite its name, Gamma Knife radiosurgery does not involve surgical incisions. This makes it less risky, especially when compared with traditional neurosurgery.
The risks and side effects of Gamma Knife radiosurgery may include:
- Nausea and vomiting
- Swelling in the brain, which may show up approximately 6 months after surgery instead of immediately
- Red and irritated scalp, especially where the head frame was worn during the procedure
- Numbness or tingling sensation on the scalp where the surgery pins were placed
- Hair loss, if the tumour is close to the scalp
How do you prepare for a Gamma Knife radiosurgery?
Your doctor will advise you on how to prepare for your Gamma Knife radiosurgery. Some advice may include:
- Fasting from food and drinks from midnight before the procedure.
- Wearing comfortable, loose-fitting clothes on the day of your procedure.
You should also inform your doctor if you have:
- Medications that you are currently taking, in case they may affect the surgical outcomes.
- Allergies to shellfish or iodine (if any), as both are chemically related to the dyes that may be used during the procedure.
- Implanted medical devices that are in your body, such as a pacemaker, artificial heart valve, aneurysm clips, neurostimulators or stents.
What can you expect in a Gamma Knife radiosurgery?
Gamma Knife radiosurgery generally involves specialised equipment and imaging scans. Usually, only sedation or local anaesthesia is needed. As patients do not have to go under the knife, there is a reduced risk of infection and bleeding.
Most patients do not feel any pain but may feel slight discomfort from the local anaesthesia. A headframe, which is fitted onto patients to prevent any head movement, may also cause slight discomfort.
The procedure itself takes between 15 minutes – 1 hour or more. However, the preparation and planning may take the team several hours.
Before the procedure
The radiosurgery team will attach a lightweight frame to your head with 4 pins. You will receive local anaesthesia where the pins will be placed. The pins will be placed on each side of your forehead and in the back of your head. This frame stabilises your head during the radiation treatment and serves as a reference on where to focus the beams of radiation.
You may feel pressure for a few minutes as the pins are tightened. This sensation will remain until the frame is removed at the end of the entire procedure.
Next, a radiation therapist will take measurements of your head. They will also perform either a computerised tomography (CT) or magnetic resonance imaging (MRI) scan on you, with the head frame in place. If necessary, a small needle may be placed in the back of your hand or in your arm to inject a dye into your blood vessels. This highlights tumours and blood vessels and helps with the planning.
Lastly, the radiosurgery team will review the results of your brain scans to determine the:
- The areas to treat
- The doses of radiation to administer
- How to focus the radiation beams to treat the areas.
This planning process may take 1 – 2 hours. During this time, you can relax in another room. The frame will remain attached to your head.
During the procedure
Once the team is ready to begin your treatment, you will lie on a bed that slides into a Gamma Knife machine that delivers the radiation. Your head frame will be attached to a helmet inside the machine.
You should not feel the radiation or hear noise from the machine. There will be a microphone that allows you to communicate with the team during the procedure. The team will also monitor you closely using cameras from immediately outside the room.
After the procedure
The table will move out of the machine, and the radiosurgery team will return to the room. They will remove the head frame for you. After about 30 minutes, you should not feel much pressure from the head frame.
You may experience minor bleeding and tenderness at the pin sites. You will also be given medications in case you experience headache, nausea or vomiting after the procedure.
You will be monitored in the observation area for up to an hour before being discharged.
Care and recovery after Gamma Knife radiosurgery
On the morning after your procedure, you can remove the bandages on your pin sites. Clean the sites twice a day with hydrogen peroxide or mild soap and water. You can also apply a small amount of antibiotic ointment on the pin sites for 3 – 4 days. Leave the pin sites exposed as they will heal rapidly.
You should wait for 24 hours before washing your hair. Waiting allows the pin sites to heal and prevents infection from developing in the wounds. If there is any bleeding, press on the area with tissue paper for 10 minutes.
Call your doctor if you notice any of the following:
- Pin sites feel hot to the touch.
- Cloudy or foul-smelling drainage leaking from the pin sites.
- You have a fever of 38°C or higher.
Head to the accident and emergency clinic if you experience any of the following:
- Severe headache
- Difficulty speaking
- Visual changes
- A seizure