NOTE: The following article is a rough translation of an article I have written in Finnish for the Finnish MS Foundation magazine Avain - Neurologinen aikakauslehti. The original of the text is available here. Please note that this article has not been written by a medical professional.

TRIGEMINAL PAIN

Jakke Mäkelä

Translated from the Finnish by Mona Martin, Jakke Mäkelä, and Bertel Stenius

Trigeminal neuralgia is a rare neurological condition. It is one of the most painful afflictions known to man. Trigeminal neuralgia may appear as a symptom of Multiple Sclerosis but it also exists independently.

The trigeminal nerve, one on each side of the face, is the largest nerve of the face. It transmits various kinds of signals, for example pain, pressure, and heat. It also enervates some of the chewing muscles.

In this article I will use the term "trigeminal pain" in a rather loose sense, covering what is known as classical or typical trigeminal neuralgia as well as so-called atypical trigeminal neuralgia. In addition, there exists a diagnosis called atypical face pain, which is related to trigeminal neuralgia but is usually considered a separate condition.

CLASSICAL TRIGEMINAL NEURALGIA

Classical trigeminal neuralgia fills certain, rather precisely defined criteria.

Spasmodic pain. The pain comes in short spasmodic attacks. It is often described as resembling electric shocks. A typical attack lasts only a few seconds. Several attacks can, however, follow each other within minutes. The pain is, at its worst, completely paralyzing.

Locality. The pain usually appears very locally within the area of the trigeminal nerve and does not radiate into other areas. The pain almost always appears on only one side of the face.

Trigger points. So-called trigger points are typical of trigeminal neuralgia. These are points in the face which, if touched even lightly, will trigger a pain attack. Such points can be located in the lips, on the side of the jaw, underneath the eye, in the eyelid, or anywhere where the trigeminal nerve reaches.

Trigger activities. If an activity causes a trigger-point to be touched, it may start an attack. For example, eating can become almost impossible. Loss of weight is common among those suffering from trigeminal neuralgia. Shaving, applying make-up, and even talking can become difficult. In some cases even a gust of wind can be enough to start an attack. An attack can, however, also start without provocation.

Remissions. So-called remissions, or painless periods, are typical of classical TN. Such a period can begin completely unpredictably and last from a few days to weeks or even months. In this case the pain is completely absent and life does not feel abnormal in any way. Without medical care the pain will, however, usually appear again sooner or later.

ATYPICAL TRIGEMINAL PAIN

Unfortunately, actual diseases seldom correspond exactly with definitions. If only some of the symptoms described above fit in or other symptoms occur, the condition will be diagnosed as atypical trigeminal neuralgia. For example, the pain may be burning or squeezing rather than electrical in nature. It can be continuous as well.

Atypical facial pain is an even more unspecific diagnosis. This diagnosis often appears to be used as a kind of 'trash can': when doctors do not know what causes the pain, they diagnose it as atypical facial pain. The symptoms can be very similar to those of trigeminal neuralgia. However, it is possible that the cause of pain is something other than pure nerve damage to the trigeminal nerve. For example, a faulty bite can cause atypical facial pain.

The actual classification of patients into one or other of these groups is not always easy. It is my personal view that these diagnoses are in fact not necessarily separate conditions, but rather a continuum of differing nerve pains. At one end is classical trigeminal neuralgia with its clear-cut and well-defined symptoms. At the other end is atypical facial pain, with extremely loosely defined and fluctuating pain. Most actual cases fall between these two extremes.

Common to all these conditions is that they occur in the area of the trigeminal nerve. In the following I will treat all three together, as expressions of the same basic phenomenon.

WHAT CAUSES TRIGEMINAL NEURALGIA?

It is not always possible to determine what causes trigeminal pain. However, several possibilities exist.

Compression of the nerve root. Compression of the nerve root is nowadays often considered to be the basic cause of classical trigeminal neuralgia. However, other opinions still exist. In this case a small blood vessel pinches the root of the trigeminal nerve. The spasms may be due to the pulsing of the blood vessel, which squeezes the nerve even more.

Damage to the myelin sheath. Damage to the myelin sheath can cause trigeminal pain. This type of damage occurs typically in connection with Multiple Sclerosis (MS). In a somewhat simple way the damage can be seen as a kind of short circuit, the way it is presented in picture 2 (not included here, as I have no scanner, sorry...). Normally, sensations of pain and heat are transmitted by different nerve routes. The myelin sheath of the nerves isolates these routes from each other. If the myelin sheath is damaged, different signals blend together and thus the nerve identifies as pain something that it would, for example, normally feel as a light touch.

Other nerve damage. Accidents, unsuccessful dental work, or various infections can damage the Trigeminal nerve. In this case the damage mechanism is probably similar to that in MS patients. The varicella virus, which causes herpes zoster, can sometimes also cause an intense pain in the trigeminal area. This pain is particularly difficult to treat.

Functional problems. Functional problems in the joints or the bones of the face are often believed to be the cause of atypical facial pain. The jaw bone may squeeze the nerve, and the squeezing is perceived as pain. This pain then causes tension in the muscles of the face, which causes the nerve to be squeezed even more tightly. It can be extremely difficult to break such a vicious circle.

Psychological reasons. 'Psychological reasons' are often mentioned as the underlying cause of atypical face pain. There is no doubt that psychological factors influence the patient's tolerance of pain and how he or she relates to it. Regrettably, however, doctors often use these psychological reasons as a kind of weapon, and do not try to treat the real problem which causes the pain. Chronic pain certainly makes a person angry and depressed; on the other hand there is no reason to assume that anger and depression are the root cause of the pain.

WHO GETS TRIGEMINAL NEURALGIA?

Trigeminal neuralgia is extremely rare and it is very difficult to collect statistical data. According to one estimate, about 150 persons in a million have trigeminal neuralgia during their lifetimes. Using this estimate, there would be a few hundred persons suffering from trigeminal neuralgia in Finland. I venture to say, however, that there are more of us.

Persons with MS may get trigeminal neuralgia as a secondary symptom. This is, however, relatively rare; it occurs in about one percent of the MS patients. In general, trigeminal neuralgia is an independent condition.

Classical trigeminal neuralgia seldom begins before a person is fifty years old. It has been suggested that blood vessels harden with age, and thus nerves are more easily squeezed.

Trigeminal neuralgia occurs somewhat more often in women than in men. The cause for this is not known. Atypical facial pain especially been called an 'old ladies' disease'. The statistics are, however, not very reliable.