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TRIGEMINAL NEURALGIA
Trigeminal neuralgia (TN) is paroxysmal triggered face pain. Most
patients respond very well to radiosurgery with the Gamma Knife,
which is one of the best standard treatments for this condition.
Symptoms
Trigeminal neuralgia is characterized by sudden bursts (paroxysms) of
face pain. These bursts are often triggered by a light touch around
the mouth or face or by talking, eating, or brushing one's teeth. The
pain sometimes gets worse or better for periods of weeks or months.
The pain is in the areas supplied by the trigeminal nerve: the cheeks,
jaw, teeth, gums, lips and less often around the eye or forehead.
Usually pain occurs on just one side of the face, but in five to 10
percent of patients, pain occurs on both sides of the face, although
not at the same time. The pain responds to Tegretol (carbamazepine is
the generic name), but sometimes the dose has to be increased and
unpleasant side effects can occur.
Atypical features may coexist with some of the previously described
symptoms. These atypical features may include a constant pain that is
not always triggered by light touch. Patients with constant pain and
TN are sometimes diagnosed as having atypical trigeminal neuralgia.
Gamma Knife radiosurgery and other treatments for TN usually relieve
the sharp electric-like pains that are triggered by light touch, but
are less likely to relieve the constant, untriggered pains.
Incidence and Prevalence
Approximately 14,000 people develop TN each year in the United
States; about 140,000 people have the condition. Trigeminal neuralgia
is more common in patients with multiple sclerosis.
Cause
The cause of trigeminal neuralgia is not always certain. Approximately
five percent of patients have a tumor pressing on the trigeminal nerve
where it leaves the brain, while other patients have a blood vessel
that presses on the trigeminal nerve, close to the brain. In some
patients the cause cannot be determined.
Approximately five percent of patients with trigeminal neuralgia have
multiple sclerosis. Patients with TN and multiple sclerosis are
generally younger, and tend to first experience TN symptoms while in
their mid 40s. These patients are more likely to have pain on both
sides of the face (bilateral trigeminal neuralgia) and often have
other neurological abnormalities, such as weakness or numbness in the
arms or legs, dizziness, unsteadiness and double vision. Most patients
in their 40s and 50s who have trigeminal neuralgia do not have multiple
sclerosis. Patients who have TN but not multiple sclerosis tend to
first experience TN symptoms while in their mid 50s.
Diagnosis
In addition to a thorough history and physical examination, magnetic
resonance imaging (MRI) of the brain is recommended. This procedure
helps identify a brain tumor in the rare cases in which it is present
along with TN. It may also help to diagnose multiple sclerosis.
Often when the MRI is performed, some contrast material is injected
into the vein so that the appearance of a small tumor, blood vessel, or
other structures in the brain can be enhanced and made easier to
detect.
Nonsurgical Treatment
There are some patients who have very mild face pain that may subside
and even disappear without treatment. For severe pain, medications,
especially Tegretol, are often highly effective. Tegretol can cause
many side effects including sleepiness, forgetfulness, confusion,
drowsiness, dizziness and nausea. Tegretol can also cause more serious
problems such as bone marrow suppression, which can lead to anemia or
a decrease in the number of white blood cells. A low white blood cell
count can predispose a patient to contracting an infection. Rarely,
these problems are life threatening. Blood counts must be monitored
in order to lessen the chance of these complications occurring.
Tegretol can also harm many other parts of the body, so patients who
take this medicine must be under careful medical supervision.
Tegretol interacts with many medications, so patients must advise their
doctor of all the medications they are taking. Elderly patients and
those with multiple sclerosis are more likely to experience the side
effects of Tegretol.
There are other medications that can be used either alone or in
combination to control trigeminal neuralgia pain. These are usually
less effective than Tegretol. They include Lioresal (baclofen),
Dilantin (phenytoin), Klonopin (clonazepam), Neurontin (gabapentin),
or Lamictal (lamotrigine). All of them, except baclofen, are also
used to prevent seizures.
Surgical Treatment
A surgical procedure is recommended for patients who continue to
experience severe pain or side effects from medications. In the past,
patients with TN did not consider neurosurgical options until the pain
or medicines became unbearable, because surgical procedures carried
higher risks. Now that surgery is safer, and especially with GKRS,
which is not only highly effective but safer than any of the other
procedures, patients no longer have to wait to be in agony in order to
undergo neurosurgical intervention.
There are five important neurosurgical procedures. Each is effective,
but not always, and occasionally has to be repeated. These procedures
are: Gamma Knife radiosurgery (GKRS), radiofrequency
electrocoagulation (RFE), glycerol injection (GLY), balloon
microcompression (BMC), and microvascular decompression (MVD). All of
these procedures treat the trigeminal nerve at around the same place,
close to where it leaves the brain.
Gamma Knife radiosurgery is the most recent and least invasive
neurosurgical treatment for trigeminal neuralgia. Of all the surgical
procedures, it is least likely to cause complications and uncomfortable
new facial sensations (dysesthesias).
What is Gamma Knife Radiosurgery?
Gamma Knife radiosurgery is a method for treating certain problems in
the brain without making an incision. Two hundred-one beams of
cobalt-60 radiation are focused precisely on a specific region in the
brain. In the case of TN, the target area is the trigeminal nerve,
just where it leaves the brain. The treatment does not require
general anesthesia, and the patient stays in the hospital for less than
five hours.
Who is a candidate for Gamma Knife Radiosurgery?
Any patient with trigeminal neuralgia who has pain or has difficulty
with the medicines used to relieve the pain is an excellent candidate
for GKRS. The patient's age or medical condition does not affect the
decision to have GKRS. Even the elderly or medically infirm can
undergo this treatment. Patients who are receiving anticoagulants for
other medical conditions do not have to stop or reverse the
anticoagulation therapy prior to GKRS. Those who have had previous
procedures for TN may also undergo GKRS. Patients who are concerned
about the possibility of numbness are particularly good candidates for
GKRS, because the chance of postoperative numbness occurring is very
small. Patients who poorly tolerate medicines given for sedation and
relief of pain during a procedure are also very suitable for GKRS
because these medications are not necessary.
What results can be expected from GKRS?
Excellent or good pain relief occurs in approximately 85 to 90 percent
of patients. Onset of pain relief may occur one day to four months
after the procedure. About half of patients will experience pain
relief within four weeks. Recurrent pain occurs within three years in
10 percent of patients. Patients with TN and multiple sclerosis are
less likely to respond to GKRS than those without multiple sclerosis,
although they also may be helped by the procedure. Gamma Knife
radiosurgery can be repeated, but not until at least four months after
the original procedure.
What are the complications from GKRS?
Major complications have not been reported. Additional numbness in the
face or new facial sensations occur in less than 10 percent of
patients. There are theoretical possibilities of delayed complications
such as brain damage or brain tumor formation, but these are rare and
have not been reported to occur in any patients treated for trigeminal
neuralgia.
Gamma Knife radiosurgery was first performed in Sweden in the 1950s,
but few patients were treated for TN. The Gamma Knife has been used
in the United States since 1987, and most cases of TN have been treated
during the past five years. Although there is not much information on
long term effects, initial and medium range follow-up suggest that
GKRS is not only effective but also very safe.
Linear Accelerator Radiosurgery
There is another form of radiosurgery, called LINAC (Linear
Accelerator) radiosurgery. It uses high-energy X-rays delivered by a
sequence of arcs, and is very different from GKRS. Only a few cases of
TN have been treated with LINAC radiosurgery, and there are no reports
on these cases in peer-reviewed journals. Unlike GKRS, LINAC
radiosurgery has not been demonstrated to be an effective and safe
treatment for trigeminal neuralgia.
Radiofrequency Electrocoagulation, Glycerol Injection and Balloon
Microcompression
These procedures are performed through a needle that is inserted into
the face and directed, under X-ray guidance, toward the trigeminal
nerve. All of these procedures partially damagee facial numbness,
which is sometimes very painful. Major complications, such as
bleeding or infection in the brain, are rare but can be devastating
when they occur.
Microvascular Decompression
Microvascular decompression is a major neurosurgical procedure in
which the skull is opened. During the operation, which requires
general anesthesia, the surgeon sees the nerve. If he or she finds
a blood vessel pressing on the trigeminal nerve, a soft piece of
material will be placed between the blood vessel and the nerve, thus
lifting the blood vessel away from the nerve. This operation carries
greater risks than the other procedures do, and these risks, although
infrequent, include possible death, stroke, bleeding, infection,
inflammation of the surface of the brain, facial weakness, hearing
loss, facial numbness and pain.
Summary
Gamma Knife radiosurgery is a major advance in the treatment of
trigeminal neuralgia, an otherwise agonizing condition characterized by
paroxysmal triggered face pain. Gamma Knife radiosurgery not only
relieves the pain as well as the other neurosurgical forms of
treatment, but it does so with fewer complications.
The Gamma Knife is the only radiosurgical machine for which positive
results of trigeminal neuralgia treatment have been published in
peer-reviewed journals.
Dr. Brisman is a graduate of Harvard Medical
School and served as Chief of Neurosurgery US Army 24th Evacuation
Hospital in Vietnam. He has performed more than 1400 surgical
procedures on TN patients and more than 125 radiosurgical procedures.
He serves on the Medical Advisory Board to the Trigeminal Neuralgia
Association. He may be reached at Columbia Presbyterian Medical
Center in New York City at +212-305-5285 or by e-mail at:
rb36@columbia.edu.
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