Trigeminal Neuralgia


General Overview
Trigeminal neuralgia (also known as "tic douloureux") is one of the most painful conditions known to adults. The affliction is characterized by sudden, electric shock-like bolts of intense pain in just one side of the face (although it may occur on both sides).

The pain can occur without any warning. Often it is triggered by normal daily activities like talking, chewing, washing the face, brushing the teeth, shaving, blowing the nose, drinking, or even smiling. It can come from something as simple as a touch or a light breeze on the face.

Episodes range from a few seconds to several minutes in length, from occasional to frequent, and from mild twinges of pain to severe shocks. Some patients have less than one attack a day, while others experience a dozen or more every hour. There may be a pain-free remission lasting several months or longer.

Although this condition is relatively rare, it affects an estimated 40,000 people in the United States annually. Persons of all ages could have the condition, but it rarely affects anyone under age 50. It is slightly more prevalent in women than in men.

The Cause:
The pain comes from a blood vessel (usually an artery) compressing the trigeminal nerve at the point where it enters the brain. In about five percent of the cases, however, a tumor or an aneurysm is the cause. In another five percent of the cases, when it occurs in younger people, multiple sclerosis (MS) is the cause. Because of this, it is recommended that all patients with trigeminal neuralgia have a magnetic resonance imaging (MRI) or computerized tomography (CT) scan before proceeding with surgery for the condition.

Making the Diagnosis:
The condition is diagnosed based on the patient's description of the symptoms. No test can definitively confirm the presence of trigeminal neuralgia. Scans are done to exclude other causes of facial pain such as tumors or multiple sclerosis. The pain should have the typical severe, intermittent character and be limited to one side of the face. The response to carbemazepine (Tegretol®) is confirmatory.

Treatment:
The ideal treatment would permanently relieve the pain while avoiding facial numbness and have no risk. The ideal treatment does not exist. However, there are many tools available for the management of trigeminal neuralgia that can help its victims lead a reasonably normal life.

Trigeminal neuralgia can be approached with two different goals: control or cure. The first approach is usually to attempt to achieve control with medication.
  

Controlling Trigeminal Neuralgia:

Medication:
Anticonvulsant drugs, which were originally developed to treat seizures, are the most common medications used to treat trigeminal neuralgia. Drugs such as carbamazepine (Tegretol®, Carbatrol®) slow the function of the irritated nerve and consequently relieve the pain. Other medications, such as phenytoin (Dilantin®) and oxcarbazepine (Trileptal®) can be tried. In the early stages of the disease, medication is effective for the majority of people. However, there can be several drawbacks. Some patients may need a relatively high dose to alleviate the pain, which could produce negative side effects such as drowsiness or slowness in thinking.

Further, because the anticonvulsant may lose its effectiveness over time, patients may need a higher dose to reduce the pain, or may need a second anticonvulsant, which can lead to adverse drug reactions. Muscle relaxants may be used in combination with anticonvulsant medications to increase their effectiveness. However, they, too may produce side effects and the more medications that are combined, the greater the risk of side effects. When these medications are used for trigeminal neuralgia, quick relief is the rule, and the reaction to medication itself is important in confirming the diagnosis.

When a patient shows no relief from the medication, a physician has cause to doubt whether trigeminal neuralgia is present. While some who have trigeminal neuralgia receive adequate pain control with medications only, others eventually stop responding to their medications or they experience undesirable and intolerable side effects. These side effects and allergic reactions are the main reasons that many people with trigeminal neuralgia ultimately seek other methods of treatment. For those people, surgery — or a combination of surgery and medications — may be the best option.

Surgical Control:
The goal of a number of surgical procedures is to gently damage the trigeminal nerve. Such damage usually relieves the pain for a period of time. Unfortunately, as the nerve recovers from the injury the pain often recurs. Complete destruction of the nerve is avoided because it is not always successful and when it fails the combination of a completely numb face with continuing trigeminal neuralgia (called "anesthesia dolorosa") is even worse than the pain alone.

Surgical options for control of trigeminal neuralgia include removing part of the nerve, causing gentle injury through a needle placed in or near the nerve through the cheek, or focusing a beam of radiation on the nerve.

Nerve avulsion involves surgically removing a branch of the nerve as it enters the face. This applies to a small group of patients whose pain is limited to a single small branch of the nerve in the face (supraorbital, infraorbital and mental nerves).

Percutaneous rhizotomy is an outpatient procedure that involves placing a needle through the cheek into the opening in the skull through which a branch of the trigeminal nerve travels toward the lower jaw. Through that needle several different procedures can be done: bathing the trigeminal cistern with glycerol (glycerol rhizolysis), burning a lesion in the nerve with radio frequency waves (radiofrequency rhizotomy), and squeezing the nerve by inserting and inflating a small balloon (balloon compression). These procedures are generally done with sedation and brief anesthesia as outpatient procedures.

Radiosurgery is the technique of causing partial nerve injury with highly focused radiation. There are a number of different devices used to carry out the extremely precise focusing of the radiation beam. Among the most common is the Gamma Knife®, but all use similar highly focused radiation. Radiosurgery requires no incision, but the most precise require the attachment of a frame to the skull in order to assure that the head does not move during treatment. Radiosurgery is also typically an outpatient procedure. The major disadvantage of radiosurgery is that the effect is not immediate and may take weeks or months to achieve pain control.

Because the success of these procedures depends on damaging the nerve, one side effect is facial numbness of varying degrees. Also, as the nerve recovers from its injury the pain frequently recurs. In most cases, one of these procedures can be repeated, but repeated injury may lead to the development of permanent abnormalities in the nerve associated with numbness or unpleasant abnormal sensations called "dysesthesias".


Cure
Only one approach to treatment offers the possibility of cure. About two-thirds of patients who undergo microvascular decompression (MVD) of the trigeminal nerve for typical trigeminal neuralgia remain free of pain and off medication 20 years after their operation. While MVD is a sophisticated microsurgical operation and requires a hospital stay of several days, the vast majority of patients who have this procedure performed by an experienced neurosurgeon have no facial numbness, require no further medications and do not have other important complications of surgery. For those whose pain recurs after MVD the previously mentioned procedures for control can still be done.

MVD is generally best for those who seek cure rather than control of their pain, are in good health, and are relatively young. Because numbness is avoided, it is often the preferred treatment when the forehead and eye are the site of pain. Because of the potential for cure and avoidance of nerve damage, it is probably the best first surgical treatment for people who are healthy enough to tolerate the surgery.

The Outlook
It's possible that trigeminal neuralgia will go away on its own — but highly unlikely. A trial of medication is almost always warranted before considering surgery. However, since many patients will eventually stop responding to drug therapy, surgery may be the only alternative. On a positive note, the vast majority of patients who undergo surgery experience significant pain relief.

For more information, please visit the Trigeminal Neuralgia Association website.


 
 

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