Knife is a procedure which has been in use since 1968, when
Dr. Lars Leksell, a Swedish neurosurgeon, introduced the device
in Stockholm, Sweden. The device is known for its
low complication rate because of its accuracy and precision.
The device focuses 201 gamma rays, emitted from Cobalt, into
a focal point at the center of the sphere. While the
center (where the target is) gets an enormous amount of delivered
radiation, any other portion of the sphere (brain) gets a
Knife procedure requires a team approach, with a neurosurgeon,
radiation oncologist, physicist, radiologist, nurse, and radiation
therapist being involved intimately with the care. The
procedure is relatively painless, with the only mild discomfort
occurring during the initial frame placement.
The remainder of the day of treatment is just "boring."
There is no shaving of the head required, and the patient
can resume most normal activities the next day. There
have been over 160,000 treatments of Gamma Knife performed
day of Gamma Knife treatment, the patient is taken to the
Gamma Knife area, and a Leksell frame (a titanium alloy frame)
is placed on the patient's head. Four pins are affixed
to the scalp and skull. The patient is sedated, and
local numbing medicine is used during the frame placement.
Often patients will not even remember this part of the procedure.
Next, the patient is taken to the MRI or CT scanner, where
detailed images of the brain are taken. The images are
transported by computer to the Gamma Knife planning station,
where the neurosurgeon, radiation oncologist, and physicist
will outline the area to be treated, and formulate a dose
plan. All three will agree upon the final treatment
plan before treating. Next, the patient will be taken
to the Gamma Knife room, and treatment will commence.
The treatment is painless. Depending upon the size and
shape of the lesion being treated, a number of different positions
("shots") will be used. After
completing the treatment, the frame will be removed, and the
patient discharged home.
Gamma Knife is used for the treatment of arteriovenous malformations,
the likelihood of obliterating the AVM is on the order of
80%. The arteriovenous malformation may take up
to two years to disappear. If this does not occur, the
malformation is still at risk for hemorrhage.
Risks for Gamma
Knife for tumor can be broken down into two categories, 1)
those related to the operative site of the tumor, and 2) those
related to the risks of anesthesia.
related to the operative site
site: The patient has a frame placed on the head.
There are potential risks associated with this, although
they are very small. There may be bleeding or infection
associated with the pin placement, and a pin could potentially
pierce the skull causing damage to the underlying brain,
although these risks are very small.
injury: Risks mainly relate to the location of
the avm, and radiation to the surrounding brain tissue.
There could be swelling of the surrounding brain.
There could be concomitant seizures, paralysis, stroke,
coma and death. The likelihood of these is very small.
There may be radiation necrosis (dead brain tissue and swelling)
associated with the treatment, requiring open surgery to
remove. There is the risk of persistence of the avm,
requiring either additional surgery or gamma knife.
Open surgery may be needed for persistent avm, and the open
surgical removal may be more difficult as a result of scarring.
If the avm is located close to the optic nerves (nerves
to the eyes), there is a risk of blindness, although the
Gamma Knife team will do everything possible to minimize
these risks. In addition, there is the theoretical
risk of the radiation exposure causing another tumor within
the brain or elsewhere in the body.
Risks: As a result of the sedatives and local
anesthetics used during the procedure, patients may
potentially experience cardiac or lung difficulties, although
the likelihood is extremely low. There is also the
risk of difficulty with the angiogram used during the procedure,
to localize the avm. There could be a reaction to
the intravenous contrast dye, and there could be bleeding
from the angiogram site in the leg. The angiogram
could cause a stroke by pushing an embolus into the brain,
or the arteries in or feeding the brain could become injured.
Blood clots in the legs, heart attacks, reaction to the
anesthetic (local anesthetic and IV sedation used during
There is relatively
little pain associated with Gamma Knife. Your surgeon
will prescribe pain medications for any pain associated with
the pin sites, although this will most likely be minimal.
- Follow up
appointment will be scheduled with your neurosurgeon and
- Take it easy
the remainder of the day. You may be tired from a
- You may resume
activity the following day. You may take the day off
from work, but could most likely return to work, if you
have been working, two days after the treatment.
- Keep the pinsites
clean, and covered with an antibiotic ointment until healed,
This will take several days.
- You may shower
after you go home. Keep the pinsites dry and clean.
- Sexual activities
- If you notice
swelling, redness or opening of the pinsites, or if there
is any clear fluid draining from it, please contact your
surgeon immediately! If you develop a fever, stiff
neck or chills, contact the office immediately. Take
your temperature at 4:00 PM daily until the clips are removed.
Call if greater than 101 degrees Fahrenheit.
- If you have
a seizure, notify our office or come to the emergency room.
- If you develop
any new weakness, notify our office.
- If you have
any questions, call our office, and for after hours emergencies,
call the medical society.
- Take your
medications prescribed on discharge from the Gamma Knife
department, as directed. Your Gamma Knife team will
determine whether steroids or other medications are needed.
- Make sure
to follow up with any other physicians involved in your
care. These may include your family physician, neurologist,
radiation oncologist and oncologist.