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
minimal dose. For the treatment of trigeminal neuralgia,
the treatment involves placing a single shot of radiation
at the point where the trigaminal nerve (nerve supplying sensation
to the face) leaves the brainstem.
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. For trigeminal neuralgia,
one shot of radiation is used. After completing
the treatment, the frame will be removed, and the patient
For the treatment
of trigeminal neuralgia, Gamma Knife has an 80 - 85% chance
of a achieving a good to excellent result at two years after
treatment. A excellent result would mean the patient
is pain free while off of any medications (such as pain medications
or carbamazepine (Tegretol)), while a good result would be
significantly reduced pain, while still on medication.
Improvement in pain may take from several days up to 3 months
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 treatment, and
radiation to the surrounding brain tissue. The target
site is the trigeminal nerve (supplies sensation to the
face, and is the cause of the facial pain) at the point
where it leaves the brainstem. The goal of the treatment
is to relieve pain while leaving sensation intact.
There is a risk that numbness may occur. There is
a very small chance that the patient may experience anesthesia
dolorosa, with resulting severe burning pain.
There could be concomitant seizures, paralysis, stroke,
coma and death. The likelihood of these is very small.
In addition, there is the theoretical risk of the radiation
exposure causing another tumor within the brain or elsewhere
in the body. Even if the treatment is successful,
pain may recur in the future.
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.