Trigeminal Neuralgia
Cheryl A. Glass and Barbara I. Bailes
Definition
A.Trigeminal neuralgia (TN), also known as tic douloureux, is a chronic pain condition of the face. There are two types: Type I or TN1 and Type 2 or TN2:
1.TN1 causes extreme, sporadic, sudden burning or shock-like facial pain that may last from a few seconds to as long as 2 minutes per episode. These attacks can occur in succession lasting as long as 2 hours.
2.TN2 is characterized by constant aching, burning, or stabbing pain of somewhat lower intensity than TN1.
3.Both can occur at the same time, in the same person. The pain can be physically and mentally incapacitating.
Incidence
A.TN occurs most often in people older than the age of 50, although it may occur at any age including infancy. The incidence of new cases is approximately 12 per 100,000 people per year. The disorder is more common in women than in men.
Pathogenesis
A.The trigeminal nerve is the fifth of 12 pairs of cranial nerves (CNs) 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, whereas the other runs to the left. Each of these nerves branches off after the nerve leaves the brain and travels inside the skull. It divides into three smaller branches:
1.The first branch controls sensation in the eye, upper eyelid, and forehead.
2.The second branch controls sensation in the lower eyelid, cheek, nostril, upper lip, and upper gum.
3.The third branch controls sensation in the jaw, lower lip, lower gum, and some of the muscles used in chewing.
Predisposing Factors
A.TN may be caused by a blood vessel pressing on the trigeminal nerve as it exits the brainstem causing the wearing away of the protective coating of the nerve (myelin sheath).
B.TN may occur in people with multiple sclerosis (MS), a disease that causes deterioration of the trigeminal nerve sheath. The development of TN in a young adult suggests the possibility of MS.
C.Injury to the trigeminal nerve resulting from sinus surgery, oral surgery, stroke, or facial trauma may produce neuropathic facial pain.
D.Hypertension (HTN) is a risk factor for TN.
E.There is evidence that TN runs in families.
F.Rarely, TN may be caused by a tumor or tangle of arteries and veins known as arteriovenous malformation (AVM).
Common Complaints
A.Pain varies depending on the type of TN and may range from sudden, severe, and stabbing pain to a more constant aching and burning sensation. The usual pattern is for the attacks to intensify over time with shorter pain-free periods.
B.Flashes of pain may occur by vibration or contact with the cheek such as with shaving, washing the face, applying makeup, blowing the nose, brushing teeth, eating, drinking hot or cold beverages, talking, or being exposed to the wind.
C.The pain may affect a small area of the face or it may spread.
D.Bouts of pain rarely occur at night when the patient is sleeping.
Other Signs and Symptoms
A.Classic pain occurs with definite periods of remission. The pain is intensely sharp, throbbing, and shock-like.
B.Atypical pain often presents as a constant, burning sensation affecting a more widespread area of the face. There may not be remission periods, and symptoms are more difficult to treat.
C.TN tends to run in cycles. Long stretches of frequent attacks will be followed by weeks, months, or even years with little or no pain.
Potential Complications
A.Uncontrollable facial twitching.
B.Attacks becoming more frequent and intense.
C.The attacks often worsen over time, eventually pain-free intervals disappear, and medication becomes less effective.
D.TN is not fatal, but it can be debilitating, causing patients to avoid daily activities or social contacts in fear of an impending attack.
E.TN may be caused by a tumor or MS.
Subjective Data
A.Ask patient what activity brought about or preceded the episode.
B.Have patient describe duration of pain and what time of day symptoms began.
C.Ask patient to describe pain—for example, crushing, stabbing, or burning—and affected areas.
D.Ask patient where sensation began and in what direction it radiates.
E.Have patient rate pain on a scale of 0 to 10, with 0 being no pain.
F.Ask patient to list all medications currently being taken, particularly substances not prescribed and illicit drugs such as cocaine.
G.Ask the patient about any other medical conditions for which he or she is being treated.
H.Ask the patient if he or she has had sinus or dental surgery or facial trauma/injury.
I.Ask what treatments have been tried so far and if anything helps the pain.
J.Ask how the pain impacts quality of life and ability to perform daily activities.
Physical Examination
A.Start with vital signs: Check temperature (if infection is suspected), pulse, respirations, and blood pressure.
B.Inspect:
1.Inspect general appearance, noting any patient discomfort.
2.Note facial appearance and evidence of tics.
C.Auscultate:
1.Heart.
2.Lungs.
D.Palpate:
1.Complete a full neurologic exam, testing all CNs.
Diagnostic Tests
A.MRI to rule out tumor or MS.
Differential Diagnosis
A.TN.
B.Brain tumor.
C.MS.
D.Temporal tendinitis (migraine mimic).
E.Ernest syndrome—injury of the stylomandibular ligament, which connects the base of skull with the lower jaw.
F.Occipital neuralgia.
G.Postherpetic neuralgia.
Plan
A.General interventions:
1.Order MRI to rule out a tumor or MS as the cause of the pain.
2.Surgery procedures are available if medications do not control the pain: percutaneous (through the skin) or open. The benefits of surgery should always be weighed carefully against the risk involved. There is no guarantee that surgery will help every individual:
a.Microvascular decompression (MVD) involves exposure of the trigeminal nerve root with gentle movement of the blood vessel away from the point of compression. MVD is the most invasive surgery for TN, but offers the lowest probability that pain will return. Approximately one-half of individuals post-MVD will experience recurrent pain within 12 to 15 years.
b.Rhizotomy involves the use of electrocoagulation (heat), destroying the part of the nerve that causes pain and suppressing the pain signal to the brain. There are several types of rhibolysis:
i.Balloon compression works by injuring the insulation on the nerve that involves the sensation of light touch on the face. A soft catheter with a balloon tip is threaded through a cannula inserted through the cheek through which one branch of the TN passes. The balloon is inflated to compress the nerve and is deflated and removed with the cannula a few minutes later. Pain relief from balloon compression usually lasts 1 to 2 years.
ii.Glycerol rhizotomy utilizes glycerol injection into the area where the nerve divides into the three branches hoping to damage the nerve, selectively interfering with the pain transmission to the brain. Pain recurrence is generally within a year or two; however the procedure can be repeated multiple times.
iii.Stereotactic radiosurgery (SRS; Gamma Knife, Cyber Knife) involves delivering a single highly concentrated dose of radiation to a small target of the trigeminal nerve. This procedure avoids many of the risks and complications of open surgery and other treatments. The slow formation of a lesion in the nerve interrupts transmission of pain signals to the brain. The International RadioSurgery Association reports 50% to 78% who are treated with the Gamma Knife radiosurgery experience pain relief within a few weeks post procedure and almost one half have recurrence of pain within 3 years.
iv.Radiofrequency (RF) thermal lesioning (RF ablation or RF lesion) is most often the procedure performed on an outpatient basis under sedation. The procedure involves passing an electrode to the area causing tingling in the area of the nerve. The nerve area is gradually heated, injuring the nerve fibers. The procedure can be repeated until desired sensory loss is obtained. Approximately half of the patients will have reoccurrence of symptoms 3 to 4 years post RF lesioning.
v.A neurectomy (partial nerve resection) involves cutting superficial branches of the TN. When performed on the face, the nerve may grow back and sensation may return.
B.Patient education:
1.Provide patient with education regarding the disease process.
2.Complementary therapies including low-impact exercise, yoga, aroma therapy, acupuncture, upper cervical chiropractic care, and biofeedback are often used in combination to drug treatment.
3. 
See Section III: Patient Teaching Guide Trigeminal Neuralgia.
C.Pharmaceutical therapy:
1.Carbamazepine, an anticonvulsant medication, is the most common medication used to treat TN. In the early stages, carbamazepine controls pain for most people but the effect of the drug decreases over time. Side effects include dizziness, double vision, drowsiness, and nausea.
2.Muscle relaxants such as baclofen, robaxin, norflex, or flexeril are especially effective when used with either carbamazepine or an anticonvulsant. Possible side effects include confusion, depression, and drowsiness.
3.Anticonvulsant medications such as phenytoin, which was the first medication used to treat TN, with possible side effects of gum overgrowth, balance disturbances, and drowsiness. Currently, more anticonvulsant medications are available for use.
4.Oxcarbazepine (Trileptal) has been used more recently as the first-line treatment and has fewer side effects, notably dizziness and double vision.
5.Other medications include gabapentin, clonazepam, sodium valproate, lamotrigine, and topiramate.
6.Botulinum toxin injections have been used with some success in blocking the sensory activity of the nerves.
Follow-Up
A.Follow-up is determined by patient needs, severity of symptoms, and whether complications are present. Monitor the patient for depression and sleep disturbance.
B.Anticonvulsant therapies may lose their effectiveness over time requiring an increase in dosage or adding a second anticonvulsant. Laboratory follow-up is necessary to evaluate bone marrow suppression, and renal and liver toxicity.
Consultation/Referral
A.Neurology referral is essential in confirming diagnosis of TN.
B.Medication initiation, titration, and management should be instituted by the neurologist.
C.Neurosurgeon referral per neurology recommendations due to medication failure and possible surgery.
D.Some patients may require supportive counseling or therapy by a psychiatrist or psychologist.
Individual Considerations
A.Geriatrics:
1.Current research postulated that pregabalin (Lyrica®) treatment for older adults suffering with TN was effective. The medication improved pain in 48.5% of patients in a clinical trial. Because of pregabalin’s effectiveness at regular and low doses with older adults, it has been recommended to prescribe to TN geriatrics preceding surgical intervention.
2.Studies have given evidence to the safety and efficacy of treating TN geriatrics ≥ 80 years with botulinum toxin type A. The dosages were comparable to treatments given to TN adults younger than 60 years. Side effects were minimal and resolved within 3 weeks.
3.Research examined MVD and SRS in TN patients that were between 62 and 73 years old and compared long-term pain control of each modality. Older adults that received MVD had longer intervals of pain control than those who elected SRS. These results could assist clinicians on what options to present to geriatrics considering surgery for TN.
4.Geriatric syndromes associated with TN:
a.Confusion related to medication side effects.
b.Depression and sleep disturbance secondary to pain.
c.Falls as a result of dizziness and sedation related to medication side effects.