Trigeminal Neuralgia

Overview

Trigeminal neuralgia, also known as tic douloureux, is an inflammation of the trigeminal nerve causing extreme pain and muscle spasms in the face. It usually occurs in adults and may affect those with multiple sclerosis. Although the exact cause of trigeminal neuralgia is not understood, several treatments can effectively relieve pain. Each treatment offers benefits, but each has limitations. You and your doctor should determine which treatment is best for you.

What Triggers A Painful Attack?

When the trigeminal nerve becomes irritated, an attack of intense pain results. Patients describe an attack as a "pins and needles" sensation that turns into a burning or jabbing pain, or as an electrical shock that may last a few seconds or minutes. In some cases of extreme pain, patients have even considered suicide. Everyday activities can trigger an episode. Some patients are sensitive in certain areas of the face, called trigger zones, which when touched cause an attack (Fig. 2). These zones are usually near the nose, lips, eyes, or ear.

 What Causes Trigeminal Neuralgia?

Many believe that the protective sheath of the trigeminal nerve deteriorates, sending abnormal messages along the nerve. Like static in a telephone line, these abnormalities disrupt the normal signal of the nerve and cause pain. Several factors can cause the deterioration of this protective sheath: aging, multiple sclerosis, tumors, but most doctors agree that it is caused by an abnormal vein or artery that compresses the nerve.

Some types of facial pain can result from an infected tooth, sinus infections, or previous nerve injury. Because the causes of pain vary, each patient should undergo a medical evaluation.

Who Is Affected?

Trigeminal neuralgia affects 1 in every 25,000 people, and occurs slightly more in women than men. Patients are usually middle age and older. Some people with multiple sclerosis also develop trigeminal neuralgia.

 Where To Get Help?

When a person first experiences facial pain, the primary care doctor or dentist is often consulted. If the pain requires further evaluation, a consultation with a neurologist or a neurosurgeon may be recommended.

How Is a Diagnosis Made?

Few causes of trigeminal neuralgia are serious. However, the possibility of a tumor or multiple sclerosis must be ruled out. Therefore, the doctor or neurologist will prescribe an imaging study, such as a computed tomography (CT) or magnetic resonance imaging (MRI) scan. The diagnosis of trigeminal neuralgia is made after carefully assessing the patient's symptoms.

 What Treatments Are Available?

A variety of treatments are available, including medications, surgical treatments, and radiosurgery. The first treatment option is usually medical.

Medications

• Analgesics such as aspirin and ibuprofen are generally not effective against trigeminal neuralgia.
• Anticonvulsants, such as carbamazepine (Tegretol), phenytoin (Dilantin), gabapentin (Neurontin), lamotrigine  (Lamictal), and oxcarbazepine (Trileptal), are commonly used because they block firing of the nerve. These medications are initially effective for pain control in 90% of patients. These drugs can cause side effects (e.g., drowsiness, unsteadiness, nausea, skin rash, blood disorders). Therefore, patients are monitored routinely and undergo blood tests to ensure that the drug levels remain safe and that the patient doesn't develop blood disorders. Medications are used as long as the pain is controlled and the side effects do not interfere with a patient's activities. When medication is no longer effective, surgical procedures may be considered. Approximately 25% of patients achieve long-term relief with medications.
• Muscle relaxants such as baclofen (Lioresal) are sometimes effective in treating trigeminal neuralgia. Sometimes multiple drug therapy is necessary to control pain  (e.g., Tegretol and Neurontin).

Surgical procedures

Medications sometimes fail to control pain or cause side effects. When this happens, the neurologist may suggest that the patient consult a neurosurgeon, who may recommend one of several surgical procedures. No one surgical procedure is best for everyone and each procedure varies in its effectiveness versus side effects (see Comparison of Treatment Results for Facial Pain). Among the current treatment options, microvascular decompression (MVD) and percutaneous stereotactic radiofrequency rhizotomy (PSR) have comparable rates of pain relief that are highest among the available options. In a review of series of approximately 100 patients or more published in the past 10 years, the rates of pain relief calculated were 77% in 7 years for MVD and 75% in 6 years for PSR rhizotomy.

• Percutaneous stereotactic radiofrequency rhizotomy (PSR), also known as electrocoagulation, produces a heating current to destroy some of the trigeminal nerve fibers that produce pain. PSR eliminates pain but also causes partial numbness of the face. This outpatient procedure is performed under local anesthesia and sedation. While the patient is awake, an electrode is passed through the cheek to stimulate the nerve and locate the pain-causing area. The patient is then anesthetized as the surgeon destroys the portion of the nerve that carries the pain.
  
  PSR is effective because it provides the most lasting pain relief by destroying part of the trigeminal nerve. PSR provides immediate pain relief for 99% of patients. Of the 15% of patients whose symptoms recur within 10 years, medication, repeat PSR, or another surgical procedure will again be considered. PSR can cause minor complications, such as double vision or weakness of the jaw. Partial numbness in the area where the pain existed is a normal side effect. Other complications, such as blurred vision or chewing problems, are usually temporary (see Percutaneous Stereotactic Radiofrequency Rhizotomy).

• Percutaneous glycerol rhizolysis is similar to PSR in that a needle is passed through the cheek to the nerve. However, it uses an injection of glycerol instead of a heating current to damage some of the trigeminal nerve fibers that produce pain. This outpatient procedure is performed under local anesthesia and sedation. The surgeon injects glycerol to damage the portion of the nerve that carries the pain.
  
  Because the location of the glycerol cannot be controlled precisely after injection, the results are somewhat unpredictable. As with PSR, partial numbness of the face is expected. Other side effects are similar to PSR.
  
  After undergoing percutaneous glycerol rhizotomy, about 70% of patients have immediate pain relief. In about 50% of patients, symptoms recur within 3 to 4 years.

• Percutaneous balloon compression is similar to PSR and PGR in that a needle is passed through the cheek to the nerve. The surgeon places a balloon in the trigeminal nerve through a catheter. The balloon is inflated where fibers produce pain. The balloon compresses the nerve, injuring the pain-causing fibers. After several minutes the balloon and catheter are removed.
  
  Complications can be minor numbness, eye infection, chewing problems, or double vision. The procedure provides immediate pain relief for 80% of patients. In about 20% of patients who undergo balloon compression, symptoms recur within 3 years.

• Microvascular decompression (MVD) is the only surgical procedure that may actually preserve facial sensation, but is the most invasive. While the patient is under general anesthesia, the surgeon makes a 1 inch circular opening at the back of the skull called a craniotomy. This opening exposes the trigeminal nerve at its connection with the brain. A blood vessel (occasionally a tumor or other abnormality) is often found that compresses the nerve. After the nerve is freed from compression, it is protected with a small sponge (see Microvascular Decompression).
  
  This procedure is effective for 95% of patients. The major benefit of MVD is that it causes little or no facial numbness. After MVD, 20% of patients have pain recur within 10 years. Major disadvantages are the risks of anesthesia and of undergoing an operation near the brain.

• Neurectomy is the irreversible cutting of the trigeminal nerve or one of its branches. Cutting the supraorbital nerve, which supplies sensation to the forehead, may be advised if pain is isolated to the area above the eyebrow. Cutting the infraorbital nerve may be performed if pain is limited to the area below the eye along the upper cheekbone. Cutting the nerve causes permanent numbness of the region that the nerve supplies and should only be considered when all other treatments have failed to control pain. Also, a neurectomy may be performed during an MVD procedure if no vessel is found compressing the nerve. In this case, a portion of the trigeminal nerve root is cut at its connection with the brain.

Questions To Ask Your Doctor

1. Is my pain caused by trigeminal neuralgia?
2. Do I need to undergo an imaging study?
3. What treatment is best for me?
4. Can trigeminal neuralgia be cured?
5. How long will I have to take medications?
6. What can I do to help control my pain?

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