What is Microvascular Decompression (MVD) for Trigeminal Neuralgia?
This is the most invasive neurosurgical procedure for
trigeminal neuralgia. It is a formal operation. The patient is admitted
to the hospital and usually will stay for 2 or 3 days. General
anesthesia is used and the patient is put to sleep for the operation. A
cut is made in back of the ear, some bone is removed, the dura (covering
of the brain is cut), the brain is gently moved out of the way, the
trigeminal nerve is seen as well as any blood vessel impinging on it.
The surgeon places some synthetic material (shredded Teflon felt) to
separate the blood vessel from the nerve. Most patients get pain relief.
Recurrence may occasionally develop but can be relieved by another
procedure, usually a Gamma Knife radiosurgery or needle rhizotomy.
Although the operation can usually be done safely, occasionally there
are complications, which infrequently can be severe.
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Who is a candidate for Microvascular Decompression for Trigeminal Neuralgia?
The best candidates for microvascular decompression for
trigeminal neuralgia are patients younger than 65 years of age, in good
medical condition, who do not have multiple sclerosis, who have not had a
prior microvascular decompression, who do not have a very large blood
vessel or vein compressing the trigeminal nerve and are willing to take a
greater risk of complications (than from Gamma Knife radiosurgery or
needle rhizotomy) in return for a smaller chance of recurrent or
persistent pain. Women are more likely than men to have recurrent
trigeminal neuralgia after microvascular decompression.
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Can Magnetic Resonance imaging (MRI) help determine if a
patient with Trigeminal Neuralgia is a good candidate for Microvascular
Often a high resolution, thin section (1 mm thick or less)
Magnetic Resonance Imaging (MRI) can provide useful information about
whether or not a patient with trigeminal neuralgia is a good candidate
for microvascular decompression. Occasionally, in about 10 percent of
patients, a very high resolution MRI will show no blood vessel in
contact with the trigeminal nerve. Under these circumstances, there is a
good chance that blood vessel compression is not the cause of the
trigeminal neuralgia and microvascular decompression is not a good idea.
In about 5 percent of the time, an extremely large and tortuous blood
vessel may compress the trigeminal nerve and cause trigeminal neuralgia.
It is very difficult to safely mobilize this very large blood vessel
away from the trigeminal nerve and microvascular decompression is not
often successful unless the nerve is significantly traumatized and
damaged; such damage can be done more safely by Gamma Knife radiosurgery
or needle rhizotomy. MRI may show that a vein (and not an artery) is in
contact with the trigeminal nerve; microvascular decompression is more
effective if an artery is compressing the trigeminal nerve. Sometimes,
MRI may show another cause for the trigeminal neuralgia (other than
blood vessel compression) such as a multiple sclerosis-like problem, and
microvascular decompression is not good for this. MRI may infrequently
(less than 5 percent of the time) show a tumor that is causing the
trigeminal neuralgia. Gamma Knife radiosurgery is often a less invasive
alternative to treat such a tumor and trigeminal neuralgia.
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If the patient has recurrent Trigeminal Neuralgia after an initial Microvascular Decompression, can it (the MVD) be repeated?
Although a repeat microvascular decompression can be done, it is not advisable because complications and recurrent trigeminal neuralgia pain are more likely with a repeat MVD, and there are less invasive and safer alternatives (Gamma Knife radiosurgery or needle rhizotomy).
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How is Microvascular Decompression done?
The patient is put to sleep with general anesthesia. Some
hair is shaved in the back of the head and a surgical incision is made
behind the ear. Bone (a little larger than a 50-cent piece) is removed
from the back of the head. The coverings of the brain are cut, and the
brain is gently moved to reveal the trigeminal nerve. The surgeon uses
an operating microscope, which provides excellent illumination and
magnification. The nerve is carefully examined to see whether a blood
vessel is pressing on it. If a blood vessel is found, it is moved away
and a soft material (padding) is placed between the nerve and blood
vessel. Sometimes, because of the particular relationship between the
nerve and the blood vessel, it is too dangerous to move the blood
vessel. Sometimes - infrequently, now that we are using thin-section MRI - a blood vessel is not found to be pressing on the nerve. Under these
circumstances, part of the trigeminal nerve may be cut or heated.
In the operating room, I (Ronald Brisman, M.D.) use precise
navigational techniques to help identify important structures in the
head. This requires that a special MRI of the head be done within 24
hours of the surgery.
During surgery, we often monitor the
function of the hearing nerve, which is close to the trigeminal nerve,
to minimize any chance of injury to this nerve.
The patient stays overnight in the recovery room and goes back to a room the next day and usually home the following day.
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What are the results following Microvascular Decompression for Trigeminal Neuralgia?
Approximately 90 percent of patients will have immediate
relief of pain. Excellent pain relief ─ no pain and no medicines ─ will
be present in 70 - 75 percent of patients one year after the surgery,
and another 9 percent will have substantial, but not complete, pain
relief. Thirty-five percent will either not obtain relief initially or
will have recurrence within 10 years.
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What are the complications from Microvascular Decompression?
If the nerve does not have to be cut or manipulated
extensively, there usually will be either no numbness or only minimal
and temporary numbness. In some cases, especially if the nerve is cut or
vigorously manipulated, which sometimes cannot be avoided, there will
be numbness, which may be permanent. There is a small chance that damage
to the trigeminal nerve may cause persistent, constant, discomforting
feelings of tightness, crawling, burning or itching or decreased
sensation and/or tearing of the eye, rarely with visual impairment.
Infrequently, there is a new numbness or pain at the site of the
surgical incision in the back of the head.
decompression is a major surgical procedure that may infrequently be
associated with major complications such as facial paralysis, brain
infection, spinal fluid leak or a permanently disabling stroke or death,
which occur in 1-2 percent of patients nationally. Fortunately, these
have not occurred in any of my (Ronald Brisman, M.D.) patients.
Diminished hearing may occur infrequently and is usually temporary.
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