Gamma 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
The Gamma 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 being
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 world wide.
On the day of
Gamma Knife treatment, the patient is taken to the Gamma Knife
area, and a Leksell 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. 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.
When Gamma Knife
is used for the treatment of acoustic neuromas, the likelihood
of arresting growth is in on the order of 90 to 95 %.
When used for meningioma, it is also 90 - 95%. Gamma
Knife may also be used for certain pituitary tumors, and may
arrest growth and suppress hormone production. It is
also useful for other benign tumors.
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
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.
Risks mainly relate to the location of the tumor, and radiation
to the surrounding brain tissue. If the tumor is adjacent
to the hearing nerve (acoustic neuroma), there may be worsening
of hearing or deafness. The likelihood of this is
fairly high. There is a small chance of injury to
the nerve supplying movement of the face. Trouble
with balance may occur. Tinnitus (ringing in the ear)
may also occur. 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 persistent growth of the tumor, and tumor recurrence.
Open surgery may be needed for persistent or recurrent tumor,
and the open surgical removal may be more difficult as a
result of scarring. If the tumor is located close
to the optic nerves (nerves to the eyes), your there is
a risk of blindness, although 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 procedure, patients
may potentially experience cardiac or lung difficulties,
although the likelihood is extremely low.
Anesthesia: Blood clots in the legs, heart attacks,
reaction to the anesthetic (local anesthetic and IV sedation
used during frame placement).
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.