sections include: mechanisms, diagnosis and treatment
Trigeminal neuralgia, formerly called tic douloureux, is a terrible shooting pain in the face. People usually remember their first attacks in great detail because they are so severe. Some individuals may feel a prodrome, or early symptom, of mild pain or “pins and needles” (paresthesia). Once the pain appears, it can recur at any time. It may last a fraction of a second or, like repetitive bolts of lightning, strike over and over again for up to an hour. An attack may be precipitated by many things: talking, chewing, feeling a cold breeze, brushing the teeth, applying makeup, kissing, and shaving. A person may set off the pain by lying down on the affected side, turning into a particular position, or turning the head. Or there may be no regular trigger.
The pains of trigeminal neuralgia are somewhat more common on the right side of the face than the left, by a ratio of 3 to 2. They are much more common in the central and lower face; the forehead, eye, and top of the head are involved in only 5 percent of cases. For most people, trigeminal neuralgia attacks can start in any area and gradually spread to the whole face, though occasionally one entire side of the face is involved from the onset.
As time passes, the pains become more frequent and more prolonged. It may no longer take being in certain positions to set off an attack; they may occur at any time. Many people find the attacks to be more severe in the winter and fall, though better pain medications have made that change harder to measure. There are rarely any other symptom than pain. A few people develop some redness of the cheek or the eye, and some develop mild numbness after many years or a serious episode.
Trigeminal neuralgia is usually a problem of middle age and later: most people are in their sixth or seventh decade when the onset occurs. The problem may occur at any age, however; when it appears in young women, they are very prone to have pain in the cheek only. There has even been a case of a thirteen-month-old baby suffering an attack. Often people having trigeminal neuralgia attacks think they have a dental problem. They may go to a dentist to have teeth extracted, root canal surgery, or other well-intentioned procedures that do nothing for the pain. Sometimes one dentist will refuse to remove a healthy tooth, and a person in pain will shop around to find another. People may also worry that the pains are a symptom of such dire problems as strokes (ischemic, hemorrhagic) or a fatal disease.
Often people have gone to three or more dentists and one or two physicians before their real problem is diagnosed. Trigeminal neuralgia is not a fatal condition, but it can be debilitating. People state that its pain is the worst they have ever had and that waiting for the next attack is almost as bad as having one. The pain can take over people’s lives, making them afraid to do things they enjoy. They can also become dependent on medications to control the pain, or be harmed by their side effects. People have even been known to commit suicide, especially before we understood the problem and developed current treatments.
Trigeminal neuralgia, we now know, is caused by an abnormality of the trigeminal nerve, which is adjacent to the area of the brain stem called the pons. Usually a blood vessel, either an artery or a vein or both, is compressing and distorting the nerve in that area. There is a clear correlation between the site of the pressure and the part of the face that is in pain. Normally the myelin sheath around the nerve protects it from “short circuits,” but there may be scattered abnormalities in that coating in patients with trigeminal neuralgia.
Occasionally something besides a blood vessel is what puts pressure on the trigeminal nerve. About 5 percent of people with trigeminal neuralgia turn out to have benign tumors pushing the nerve and blood vessel together. People with multiple sclerosis may develop the pains if a plaque is located in this area of the trigeminal nerve.
The true prevalence of trigeminal neuralgia is unknown because there have been very few studies. Experts estimate that there are anywhere from 10,000 to 25,000 new cases every year. Sixty percent of people with the disorder are women. It seems to be more common among Caucasians than among African Americans and Asian Americans, but this is not clear. There is a small genetic component, and individuals whose parents and grandparents were prone to trigeminal neuralgia tend to develop it at an earlier age.
Physicians once thought that viruses were involved, but they have nothing to do with the condition.
Diagnosis and Treatment
A doctor’s first step in diagnosing the cause of a person’s shooting facial pains is to ask for the history of those pains. As noted earlier, most people have a vivid memory of their first attack. The major diagnostic tests are to check hearing, because benign tumors may be present that cause hearing loss. The doctor will order a magnetic resonance imaging (MRI) scan to look for abnormal blood vessels, benign tumors, or the plaques of multiple sclerosis.
For most people, the best first treatment is pain medication, with the caution that the doctor and patient must carefully monitor the side effects of the prescribed drug. A number of medications have been used. The benchmark treatment is carbamazepine (Tegretol), but not all physicians know how to prescribe it. One must start with a small dose, such as 100 milligrams twice a day, and increase the dose by 200 milligrams every 48 hours until the pain is relieved. Trileptal is a new variation of Tegretol and has been useful. Gabapentin and baclofen may also be effective, and phenytoin (Dilantin) has been used.
In the long run, people with trigeminal neuralgia have to increase their medications gradually or combine them, making their side effects more worrisome. As individuals become older, furthermore, they may become less able to have surgery to fix the underlying cause of the pain. For those reasons, many people who develop trigeminal neuralgia early or in middle age may do best to have an operation to relieve pressure on the crucial nerve. All operations carry some risks: possible bad reaction to anesthetics, infection, and in this case the potential of damaging the nerve and causing permanent numbness or weakness in some parts of the face. An individual and his or her doctor must balance those risks against the potential benefits of stopping the pain.
There are a range of operative procedures available for treating trigeminal neuralgia. A person should consult with a neurosurgeon who can do various operations so that together they can choose the approach best suited to the case. As always, it is valuable to have an experienced surgeon perform an operation—especially so when working around the trigeminal nerve.
The benchmark operative procedure is the microvascular decompression, a procedure lasting about two hours. Using a small incision behind the ear, a surgeon moves the blood vessel causing the problem and inserts soft plastic implants to hold it away from the nerve. This is a very small-scale procedure, but microsurgical techniques have enabled surgeons to perform it safely and effectively. When performed using the latest techniques, this procedure has a recurrence rate of only 0.5 percent per year after the first two years.
A second procedure, appropriate for multiple sclerosis plaques, is a percutaneous radiofrequency rhizotomy. The doctor puts a needle through the cheek into the trigeminal ganglion and burns the nerve. The more severe the burn, the more pain it relieves and the longer the relief lasts. Unfortunately, there is a high incidence of side effects that are difficult to treat, including anesthesia dolorosa, or painful numbness. Up to 20 percent of people undergoing this operation develop disordered sensations, including numbness, which in some cases are worse than the initial pain.
In people too frail for surgery, the treatment of choice may be injecting glycerol into the nerve. This is a needle procedure done with the patient awake but sedated in the operating room. It produces good short-term results, and an experienced surgeon is unlikely to bring on the side effect of numbness. Unfortunately, up to half of people who undergo the procedure suffer recurrent pains within two years.
Another procedure, which has come into use only recently, is focused high-energy radiation to the nerve. This is the most costly procedure. We await long-term studies on its efficacy and whether it is followed by recurrences of pain.
Older treatments, no longer recommended, include injecting the trigeminal nerves with alcohol and cutting (sectioning) those nerves.
The promising paths of research into trigeminal neuralgia involve changing the basic metabolism of a person’s myelin to make the nerve sheaths less sensitive to compression, and, of course, developing better medical therapy.
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