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| Trigeminal
Neuralgia |
Trigeminal
neuralgia is a facial pain syndrome consisting of sharp,
lancinating pain in the face. The pain is often described as
shock-like stabs of pain. The pain is only on one side of the
face and may be elicited by touching trigger points in the
skin of gums. There is no associated numbness (unless there is
co-existing multiple sclerosis). Often there may spontaneous
remissions from pain lasting weeks to years. Interestingly,
this pain usually responds to carbamazepine (Tegretol), an
oral anticonvulsant medication.
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 Trigeminal
neuralgia is usually caused by compression of the sensory
(trigeminal) nerve within the skull by a small artery or vein
at the point where the nerve joins the brain stem. Sometimes a
small, benign tumor compressed the nerve, causing jolts of
electrical shock–like pain to radiate into the face. A few
percent of tic patients suffer from multiple sclerosis. In
this case the inflammatory response affecting the brain also
involves the trigeminal nerve, causing paroxysmal pain. |
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Tic
douloureaux is unique among pain disorders because nearly all
treatments work for a period of time. Over the years
peripheral nerve avulsion, heating, cooling, compressing,
decompressing, chemical ablation, and irradiation have all
enjoyed varying degrees of success. Because of the
effectiveness of carbamazepine (Tegretol), its use is usually
the first level of treatment. Other anticonvulsants may be
tried, but these are not usually as effective. When oral
medication fails to control this dreadful pain, other surgical
measures are quite effective. These procedures have challenged
the imagination of neurosurgeons
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Glycerol Injection
 Injection
of glycerol into the gasserian ganglion is a simple and
effective treatment. Using a brief, intravenous anesthetic a
needle is introduced into the nerve in the base of the skull
and a small amount of glycerol injected. The treatment only
takes a few minutes. Eighty-five percent of patients achieve
immediate pain relief and persisting numbness in the face is
unusual and infection is rare. Recurrence rates are relatively
high: about ˝ will recur over 3 to 4 years. Re-injection may
be performed, but glycerol injections become less effective
after several are performed. |
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Radiofrequency Rhizotomy
This procedure, first described by Sweet is similar to
glycerol injection. Aneedle-electrode
is introduced through the face into the nerve in the skull
base, once again using a brief anesthetic. A high frequency
(radiofrequency) current heats the needle tip, selectively
destroying pain nerve fibers and preserving touch sensation
nerve fibers. Patients develop some sensory loss. About 98% of
individuals have early success with a 20% recurrence rate
after a few years. Marked numbness of the eye is an unusual
hazard and infection is rare. The procedure can be repeated. |
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Balloon Compression of Gasserian Ganglion
In this treatment a small balloon catheter is introduced
through the needle
into the nerve in the skull base. With the patient
anesthetized the balloon is briefly inflated to compress the
nerve and then removed. Initial pain relief is high: 93% and
pain recurrence similar to radiofrequency treatment, about 20%
over a few years. Numbness in the face, unfortunately is high
(72%). Infection again is a hazard. |
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Microvascular Decompression
 Dr.
Peter Jennetta established cause of tic douloureaux when he
confirmed earlier observations (by Wlter Dandy)that these
patients usually had a small artery or vein compressing the
nerve in the posterior skull. He developed microvascular
decompression as an effective treatment. Under general
anesthesia a small window of bone is removed from behind the
ear to gain entry to the lower brain stem and trigeminal
nerve. Under a microscope the surgeon separates the blood
vessel from the nerve and places a cushion of Teflon cotton
between them. An overnight stay in the intensive care unit and
a few days hospitalization are required. Initial pain relief
is found in 83% of patients; facial numbness is rare and 10
year recurrence rate is 15%. Rare complications are deafness,
cerebrospinal leak and other complications of open surgery. |
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Trigeminal Neurotomy
Devised
by Walter Dandy, the posterior one-half of the nerve is
divided. This does not produce much numbness in the face, and
pain relief is frequent.
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Gamma Knife Radiosurgery
Gamma Knife radiosurgery
can successfully treat tic pain. A single, non-invasive morning
treatment has resulted in excellent pain relief in 58%; good
pain relief in 36% and failed pain relief in 6%. Transient facial
numbness is rare. Long term recurrence rates are unknown. This
treatment is a suitable alternative to anticonvulsant therapy
and compares favorably to other treatments.
Read
the personal
experience of a patient during and after her Gamma
Knife treatment submitted to the Trigeminal Neuralgia
Association, San Diego Support Group.
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| A
single 4 mm isocenter is focused on the left trigeminal nerve
for Gamma Knife treatment. |
