Anatomy - Trigeminal Neuralgia
What is Trigeminal Neuralgia?
Trigeminal neuralgia or tic douloureux is sometimes
described as the most excruciating pain known to humanity.
The pain typically involves the lower face and jaw,
although sometimes it affects the area around the nose
and above the eye. This intense, stabbing, electric
shock-like pain is caused by irritation of the trigeminal
nerve, which sends branches to the forehead, cheek,
and lower jaw. It is usually limited to one side of
Although trigeminal neuralgia cannot always be
cured, there are treatments available to alleviate the
excruciating pain. Anticonvulsive medications are normally
the first treatment choice. Surgery can be an effective
option for those who become unresponsive to medications
or for those who suffer serious side effects from the
The Trigeminal Nerve
The trigeminal nerve is the fifth of 12 pairs of cranial
nerves in the head. It is the nerve responsible for
providing sensation to the face. One trigeminal nerve
runs to the right side of the head and the other to
the left. Each of these nerves has three distinct branches.
("Trigeminal" derives from the Latin word
"tria," which means three, and "geminus,"
which means twin.) After the trigeminal nerve leaves
your brain and travels inside your skull, it divides
into three smaller branches, controlling sensations
throughout your face:
- The first branch controls sensation in your eye,
upper eyelid and forehead.
- The second branch controls sensation in your lower
eyelid, cheek, nostril, upper lip and upper gum.
- The third branch controls sensations in your jaw,
lower lip, lower gum and some of the muscles you use
Prevalence and Incidence
Advanced age is a major risk factor for trigeminal
neuralgia. The disorder is more common in women than
in men and rarely affects anyone younger than age 50.
Hypertension and multiple sclerosis are also risk factors.
Trigeminal neuralgia is relatively rare. An estimated
45,000 people in the United States and an estimated
one million people worldwide, suffer from trigeminal
While inheritance has not been conclusively established,
there is evidence that trigeminal neuralgia is tied
to family history. According to the Trigeminal Neuralgia
Association, 4.1 percent of patients with unilateral
trigeminal neuralgia and 17 percent of patients with
bilateral trigeminal neuralgia report a family history
of the disorder.
The pain associated with trigeminal neuralgia represents
an irritation of the nerve. The cause of the pain usually
is due to contact between a normal artery or vein and
the trigeminal nerve at the base of your brain. This
places pressure on the nerve as it enters your brain
and causes the nerve to misfire.
Other causes of trigeminal neuralgia include pressure
of a tumour on the nerve or multiple sclerosis, which
damages the myelin sheaths. Development of trigeminal
neuralgia in a young adult suggests the possibility
of multiple sclerosis.
What symptoms can it cause?
Most patients report that their pain begins spontaneously
out of nowhere. Other patients say that their pain follows
a car accident, a blow to the face, or dental surgery.
Most physicians and dentists do not believe that dental
work can cause trigeminal neuralgia. In these cases,
it is more likely that the disorder was already developing,
and the dental work caused the initial symptoms to be
Pain is often first experienced along the upper or
lower jaw and many patients assume they have a dental
abscess. Some patients see their dentists and actually
have a root canal performed, which inevitably brings
no relief. When the pain persists, patients realize
the problem is not dental-related.
The pain of trigeminal neuralgia is defined as either
classic or atypical. With classic pain, there are definite
periods of remission. The pain is intensely sharp, throbbing
and shock-like, and usually triggered by touching an
area of the skin, or by specific activities. Atypical
pain is often present as a constant, burning sensation
affecting a more diffuse area of the face. With atypical
trigeminal neuralgia, there may not be a remission period,
and symptoms are usually more difficult to treat.
Trigeminal neuralgia tends to run in cycles. Patients
often suffer long stretches of frequent attacks followed
by weeks, months or even years of little or no pain.
The usual pattern, however, is for the attacks to intensify
over time with shorter pain-free periods. Some patients
suffer less than one attack a day, while others experience
a dozen or more every hour. The pain typically begins
with a sensation of electrical shocks that culminates
in less than 20 seconds, with an excruciating stabbing
pain. The pain often leaves patients with uncontrollable
facial twitching, which is why the disorder is also
known as tic douloureux.
The symptoms of several pain disorders are similar
to those of trigeminal neuralgia. Temporal tendinitis
involves cheek pain and tooth sensitivity as well as
headaches and neck and shoulder pain. Ernest syndrome
is an injury of the styomandubular ligament, which connects
the base of the skull with the lower jaw, producing
pain in areas of the face, head and neck. Occipital
neuralgia involves pain in the front and back of the
head that sometimes extends into the facial region.
Magnetic resonance imaging (MRI) can detect if a tumour
or multiple sclerosis is irritating the trigeminal nerve.
However, unless a tumour or multiple sclerosis is the
cause, imaging of the brain will seldom reveal the precise
reason why the nerve is being irritated. The vessel
abutting the nerve root is difficult to see even on
a high quality MRI. Tests can help rule out other causes
of facial disorders. Trigeminal neuralgia is usually
diagnosed based on the description of the symptoms provided
by the patient.
Years ago trigeminal neuralgia was not well understood
and treatment was nearly nonexistent. Today, there are
several effective ways to alleviate the pain, including
a variety of medications. There are drawbacks to these
medications other than side effects. Some patients may
need relatively high doses to alleviate the pain and
the side effects can become more pronounced at higher
doses. Anticonvulsant drugs may lose their efficacy
over time. Some patients may need a higher dose to reduce
the pain or may need a second anticonvulsant, which
can lead to adverse drug reactions. Many of these drugs
can have a toxic effect on some patients, particularly
people with a history of bone marrow suppression and
kidney and liver toxicity. These patients must have
their blood monitored to ensure their safety.
If medications have proven ineffective in treating
trigeminal neuralgia, there are several surgical procedures
which may help control the pain. Surgical treatment
is divided into two categories: percutaneous (through
the skin) and open. In general, percutaneous approaches
are preferred in older or medically frail patients,
in patients with multiple sclerosis, or in individuals
who have failed to attain pain relief from the open
approach. The open approach is recommended for younger
and healthier patients. All of the procedures have varying
success rates and some side effects, such as recurrence
of pain and facial numbness.
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