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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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