DentCast
DentCast
Dr. Foad Shahabian
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Trigeminal Neuralgia

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What a general dentist needs to know.

∆ How this patient walks into the office

A patient comes in and says he has a terrible pain in the upper or lower jaw. Usually he also points to one specific tooth and insists that the problem is coming from it. If we are not careful, that very insistence takes us toward root canal treatment or the extraction of a completely healthy tooth. This happens so often that many of these patients have lost several healthy teeth of their own before arriving at the correct diagnosis.

∆ What makes this pain different

Five features separate this pain from dental pain:

1. The attack is short. The pain lasts a few seconds, at most up to two minutes. Then it stops completely. Pulpal pain does not behave like this; pulpitis is a drawn-out, continuous pain.

2. The character of the pain. The patient uses words such as electric shock, shooting, jolt and knife. Pulpal pain is usually described as throbbing and poorly localized.

3. The trigger zone. There is a small area on the face, gingiva or mucosa where the slightest contact starts an attack: brushing, shaving, washing the face, speaking, chewing, even a draft of air. The point here is that the stimulus is an innocuous one — something that causes no pain in any healthy person. This differs from dental pain, which is provoked by cold and heat.

4. It is unilateral. The pain is almost always on one side of the face only and does not cross the midline.

5. Sleep. This pain usually does not wake the patient in the middle of the night. Irreversible pulpitis is precisely what jolts a patient out of sleep at night.

There is one more feature that is very helpful. Immediately after an attack there is a short period during which, however much you stimulate the trigger zone, the pain will not fire. It is called the refractory period, and it is almost specific to this condition.

∆ Which part of the face is involved

In practical terms, three regions:

The second and third regions are far more common, and that is exactly why these patients go to the dentist first rather than to a physician. Involvement of the forehead region alone is rare.

∆ What the examination shows

Nothing. And that very "nothing" is the most important finding.

If the clinical picture looks like neuralgia but you find no dental explanation, that very contradiction between the severity of the pain and everything being normal is itself what makes the diagnosis.

There is also one simple thing you can do. If local anesthesia at the trigger zone completely stops the attacks for the duration of the drug's action, this supports the diagnosis.

∆ When to be more concerned

These mean that an underlying cause such as a tumor or multiple sclerosis is more likely and that referral should be more urgent:

∆ How the final diagnosis is made

The diagnosis is clinical, that is, based on this same history. But every patient should have a brain MRI with a protocol dedicated to the trigeminal nerve, so that an underlying cause is ruled out and so that decision-making is possible if surgery is ever to be considered. Ordering and interpreting this MRI is not our job; it is the neurologist's.

∆ Medication, at an introductory level only

The first-line drug is carbamazepine, with oxcarbazepine as its alternative. Both are anticonvulsants and work by calming the excitability of the nerve, not through an analgesic effect.

A few practical points:

If the patient does not respond to medication or cannot tolerate the side effects, there are surgical options, which are entirely outside our scope.

∆ The practical summary

Shock-like pain, lasting a few seconds, unilateral, starting with light touch, and all dental tests normal. In that situation, hold off. Perform no irreversible treatment on the tooth. Refer the patient to a neurologist or an orofacial pain clinic, and write in the referral note that you have examined and ruled out dental causes. That one sentence shortens the patient's journey.

∆ References

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