Trigeminal neuralgia

What causes trigeminal neuralgia?

In most cases, trigeminal neuralgia happens because something is pressing on the trigeminal nerve. This is the largest nerve inside the skull, and it carries feelings of pain and touch from your face, teeth and mouth to your brain.

This pressure usually comes from a nearby blood vessel resting against part of the nerve inside the skull.

In rare cases, trigeminal neuralgia develops because the trigeminal nerve has been damaged by an underlying condition, such as multiple sclerosis (MS) or a tumour.

Who is affected

It is not clear exactly how many people live with trigeminal neuralgia, but doctors consider it a rare condition.

Some studies suggest that around 27 in every 100,000 people are diagnosed with it in the UK each year, though this figure is probably a bit high, since the condition tends to be over diagnosed by doctors. Other estimates put the number of new cases in the UK at around 6,500 a year.

Women are affected more often than men, and the condition is rare in people under 40, although younger people can develop it too. Most people are first diagnosed between the ages of 50 and 60.

Causes of trigeminal neuralgia

The exact cause is still not fully understood, but trigeminal neuralgia is generally thought to result from pressure on the trigeminal nerve, or from an underlying condition affecting it.

The trigeminal nerve

The trigeminal nerve, also known as the fifth cranial nerve, is the largest nerve inside the skull. You have two of them, one on each side of your face. Small branches from different parts of the face come together into three main nerve branches:

The upper branch, called the ophthalmic branch, carries sensation from the skin above the eye, the forehead and the front of the head.

The middle branch, called the maxillary branch, carries sensation from the skin across the cheek, the side of the nose, the upper jaw, teeth and gums.

The lower branch, called the mandibular branch, carries sensation from the skin across the lower jaw, teeth and gums.

These three branches enter the skull through different routes and then come together at a point called the Gasserian ganglion, before connecting to the brainstem in the region of the skull known as the posterior fossa.

Trigeminal neuralgia can affect one branch of the nerve or more than one. The maxillary and mandibular branches are involved most often, while the ophthalmic branch is affected the least.

Pressure on the trigeminal nerve

Evidence suggests that in up to 95 percent of cases, trigeminal neuralgia is caused by pressure on the trigeminal nerve near the point where it enters the brainstem, the lowest part of the brain that merges into the spinal cord, just past the Gasserian ganglion.

In most cases, this pressure appears to come from an artery or vein pressing against the trigeminal nerve, though it is not known why this happens in some people and not others.

It is also unclear exactly why this pressure leads to painful attacks, since not everyone with a compressed trigeminal nerve experiences pain. One possibility is that, in some people, the pressure wears away the nerve's protective outer layer, called the myelin sheath, which may allow uncontrolled pain signals to travel along the nerve.

Even so, this does not fully explain why some people go through periods of remission, when symptoms disappear for a while, or why pain relief tends to be immediate after a successful operation to move the blood vessel away from the nerve.

Other underlying causes

The trigeminal nerve can also become compressed or damaged for other reasons, including:

a tumour, which is a growth or lump

a cyst, a fluid filled sac

arteriovenous malformation, an abnormal tangle of arteries and veins

multiple sclerosis (MS), a long term condition affecting the central nervous system, which is made up of the brain and spinal cord

Diagnosing trigeminal neuralgia

As the pain caused by trigeminal neuralgia is often felt in the jaw, teeth or gums, it is common for people to visit their dentist initially, rather than their GP.

If you visit your dentist, they will ask you questions about your symptoms and investigate your facial pain using a dental X-ray and other means to look for other more common causes, such as a dental infection or cracked tooth.

If the dentist cannot find a cause, it is important not to undergo unnecessary treatment such as a root canal filling or an extraction, even though you may be convinced that it is a tooth problem. If your dentist can’t find anything wrong, do not try to persuade them to remove a particular tooth, as this will not solve the problem.

Often, the diagnosis of trigeminal neuralgia is made by a dentist, but if you have already seen your dentist and they have not been able to find an obvious cause of your pain, visit your GP.

Seeing your GP

There is no specific test for trigeminal neuralgia, so a diagnosis is largely based on your symptoms and your description of the pain.

If you have experienced facial pain, your GP will ask you questions about your symptoms, such as how often they occur, how long the pain attacks last and which areas of your face are affected. The more details about your pain you can provide, the better.

Your GP will consider other possible causes of your pain and may also examine your head and jaw to identify which parts are painful.

Ruling out other conditions

An important part of the process of diagnosing trigeminal neuralgia involves ruling out other conditions that can also cause facial pain.

By asking about your symptoms and carrying out an examination, your GP may be able to rule out other conditions, such as:

• migraine
• joint pain in the lower jaw
• giant cell arteritis (temporal arteritis) – a condition in which medium and large arteries in the head and neck become inflamed and cause pain in the jaw and temples
• a possible injury to one of the facial nerves

Your medical, personal and family history will also need to be taken into consideration when determining possible causes of your pain.

For example, trigeminal neuralgia is less likely if you are under 40 years old, and multiple sclerosis (MS) may be more likely if you have a family history of the condition or if you have some other form of this condition. However, trigeminal neuralgia is very unlikely to be the first symptom of MS.

MRI scans

If your GP is not sure about your diagnosis, or if you have unusual symptoms, they may refer you for a magnetic resonance imaging (MRI) scan of your head.

An MRI scan uses strong magnetic fields and radio waves to create detailed images of the inside of your head. It can help identify potential causes of your facial pain, such as sinusitis (inflammation of the lining of the sinuses), tumours on one of the facial nerves, or nerve damage caused by MS.

An MRI can also sometimes detect whether a blood vessel in your head is compressing one of the trigeminal nerves, which is one of the main causes of trigeminal neuralgia. However, highly sophisticated MRI scans may be needed to show this accurately, although this may not necessarily be helpful, because not everyone with a compressed trigeminal nerve has trigeminal neuralgia.

How trigeminal neuralgia is treated

Trigeminal neuralgia is usually a long-term condition, and the periods of remission often get shorter over time. However, most cases can be controlled to at least some degree with treatment.

The first treatment offered will usually be with an anticonvulsant medication (usually used to treat epilepsy) called carbamazepine. To be effective, this medication needs to be taken several times a day, with the dose gradually increased over the course of a few days or weeks so that high enough levels of the medication can build up in your bloodstream.

Unless your pain starts to diminish or disappears altogether, the medication is usually continued for as long as is necessary, sometimes for many years. If you are entering a period of remission and your pain goes away, stopping the medication should always be done slowly over days or weeks, unless you are advised otherwise by a doctor.

Carbamazepine was not originally designed to treat pain, but it can help relieve nerve pain by slowing down electrical impulses in the nerves and reducing their ability to transmit pain messages.

If this medication is ineffective, unsuitable or causes too many side effects, you may be referred to a specialist to discuss alternative medications or surgical procedures that may help.

There are a number of minor surgical procedures that can be used to treat trigeminal neuralgia – usually by damaging the nerve to stop it sending pain signals – but these are generally only effective for a few years.

Alternatively, your specialist may recommend having surgery to open up your skull and move away any blood vessels compressing the trigeminal nerve. Research suggests this operation offers the best results in terms of long-term pain relief, but it is a major operation and carries a risk of potentially serious complications, such as hearing loss, facial numbness or, very rarely, a stroke.

Read more about treating trigeminal neuralgia

Treating trigeminal neuralgia

There are a number of treatments available that can offer some relief from the pain caused by trigeminal neuralgia.

Identifying triggers and avoiding them can also help.

Most people with trigeminal neuralgia will be prescribed medication to help control their pain, although surgery may be considered for the longer term in those cases where medication is ineffective or causes too many side effects.

Surgery and procedures

If medication does not adequately control your symptoms or is causing persistently troublesome side effects, you may be referred to a specialist to discuss the different surgical and non-surgical options available to relieve your pain.

There a number of procedures that have been used to treat trigeminal neuralgia, so you will need to discuss the potential benefits and risks of each treatment with your specialist before making a decision. It is wise to be as informed as possible and to make the choice that it right for you as an individual.

There is no guarantee that one or any of these procedures will work for you but, once you have had a successful procedure, you won’t need to take your pain medications unless the pain returns. If one procedure does not work, you can always try another or remain on your medication temporarily or permanently.

Some of the procedures that can be used to treat people with trigeminal neuralgia are outlined below.

Percutaneous procedures

There are a number of procedures that can offer some relief from trigeminal neuralgia pain, at least temporarily, by inserting a needle or thin tube through the cheek and into the trigeminal nerve inside the skull.

These are known can “percutaneous” (through the skin) procedures, and they are carried out using X-rays to guide the needle or tube into the correct place while you are heavily sedated with medication or under a general anaesthetic (where you are asleep).

Percutaneous procedures that can be carried out to treat people with trigeminal neuralgia include:

• glycerol injections – where a medication called glycerol in injected around the Gasserian ganglion (where the three main branches of the trigeminal nerve join together)
• radiofrequency lesioning – where a needle is used to apply heat directly to the the Gasserian ganglion
• balloon compression – where a tiny balloon is passed along a thin tube inserted through the cheek and is inflated around the Gasserian ganglion to squeeze it; the balloon is then removed

These procedures work by deliberately injuring or damaging the trigeminal nerve, which is thought to disrupt the pain signals travelling along it. You are usually able to go home the same day, following your treatment.

Overall, all of these procedures are similarly effective in relieving trigeminal neuralgia pain, although there can be complications with each, and these vary with the procedure and the individual. The pain relief will usually only last a few years, and sometimes only a few months. Sometimes these procedures do not work at all.

The major side effect of these procedures is numbness of part or all the side of the face, and this can vary in severity from being very numb or just pins and needles. The sensation, which can be permanent, is often similar to that following an injection at the dentist. Very rarely, you can get a combination of numbness and continuous pain called anesthesia dolorosa, which is virtually untreatable.

The procedures also carry a risk of other short- and long-term side effects and complications, including bleeding, facial bruising, eye problems and problems moving the facial muscles.

Stereotactic radiosurgery

An alternative way to relieve pain by damaging the trigeminal nerve that doesn’t involve inserting anything through the skin is stereotactic radiosurgery. This is a fairly new treatment that uses a concentrated beam of radiation to deliberately damage the trigeminal nerve where it enters the brainstem.

Stereotactic radiosurgery does not require a general anaesthetic and no cuts (incisions) are made in your cheek.

A metal frame is attached to your head with four pins inserted around your scalp (a local anaesthetic is used to numb the areas where these are inserted) and your head, complete with the frame attached, is held in a large machine for an hour or two (which may make you feel claustrophobic) while the radiation is given. The frame and pins are then removed, and you are able to go home after a short rest.

It can take a few weeks – or sometimes many months – for this procedure to take effect, but it can offer pain relief for some people for several months or years. Studies into this treatment have shown similar results to the other procedures mentioned above.

The most common complications associated with stereotactic radiosurgery include facial numbness and pins and needles (paraesthesia) in the face. This can be permanent and, in some cases, very troublesome.

Microvascular decompression

Microvascular decompression (MVD) is an operation that can help relieve trigeminal neuralgia pain without intentionally damaging the trigeminal nerve. Instead, the procedure involves relieving the pressure placed on the nerve by blood vessels that are touching the nerve or wrapped around it.

This is a major procedure that involves opening up the skull, and is carried out under general anaesthetic by a neurosurgeon.

During MVD, the surgeon will make an incision in your scalp, behind your ear, and remove a small circular piece of skull bone. They will then either remove or relocate the blood vessel(s), separating them from the trigeminal nerve using an artificial pad or a sling constructed from adjoining tissue.

For many people, this type of surgery is effective in easing or completely stopping the pain of trigeminal neuralgia. It provides the longest lasting relief, with some studies suggesting that pain only recurs in about 30% of cases within 10-20 years of surgery. Currently, this is the closest possible cure for trigeminal neuralgia.

However, it’s an invasive procedure and carries a risk of potentially serious complications, such as facial numbness, hearing loss, stroke and even death (in around 1 in every 200 cases).

More information and support

Living with a long-term and painful condition such as trigeminal neuralgia can be very difficult.

You may find it useful to contact local or national support groups, such as the Trigeminal Neuralgia Association UK, for more information and advice about living with the condition, and to get in touch with other people who have the condition to talk to them about their experiences.

Research has shown that groups that have support from health care professionals provide high-quality help, which can significantly improve your ability to manage this rare condition. Learning from others how to cope can help remove the fear of more pain and reduce the risk of depression.

However, you need to be wary of potentially unreliable information you may find elsewhere, especially if offering “cures” for the condition. There is a great deal of misinformation on the internet, so do your research only on reliable websites, not on open forums or on social media.

There are a number of research projects running both in the UK and abroad to determine the cause of this condition and to find new treatments, including new medications, so there is always hope on the horizon.

Don’t include personal information e.g. name, location or any personal health conditions.

Avoid triggers

The painful attacks associated with trigeminal neuralgia can sometimes be triggered or made worse by a number of different things. Therefore, in addition to your medical treatment, it may help to try to avoid these triggers, if possible.

For example, if your pain is triggered by wind or even a draught in a room, it may help to avoid sitting near open windows or the source of air conditioning, and wearing a scarf wrapped around your face in windy weather. A transparent dome-shaped umbrella can also protect your face from the weather.

Hot, spicy or cold food or drink may also trigger your pain, so avoiding these can help. Using a straw to drink warm or cold drinks may also help prevent the liquid coming into contact with the painful areas of your mouth. It is important to eat nourishing meals, however, so if you are having difficulty chewing, consider eating mushy foods or liquidising your meals.

Certain foods seem to trigger attacks in some people, so you may want to consider avoiding things such as caffeine, citrus fruits and bananas.

Medication

As normal painkillers such as paracetamol are not effective in treating trigeminal neuralgia, you will normally be prescribed an alternative medication, such as an anticonvulsant medication (usually used to treat epilepsy) to help control your pain.

These medications were not originally designed to treat pain, but they can help relieve nerve pain by slowing down electrical impulses in the nerves and reducing their ability to transmit pain.

They need to be taken regularly, not just when the pain attacks occur, but can be stopped when the episodes of pain cease and you are in remission. Unless otherwise instructed by your GP or specialist, it is important to build up the dosage slowly and reduce it again gradually over a few weeks. Taking too much too soon and stopping the medication too quickly can cause serious problems.

Initially, your GP will probably prescribe a type of anticonvulsant called carbamazepine, although a number of alternatives are available if this is ineffective or unsuitable.

Carbamazepine

The anticonvulsant carbamazepine is currently the only medication licensed for the treatment of trigeminal neuralgia in the UK. It can be very effective initially, but may become less effective over time.

You will usually need to take this medicine at a low dose once or twice a day, with the dose slowly increasing up to four times a day until it provides satisfactory pain relief.

Carbamazepine often causes side effects, which may make it difficult for some people to take. These include:

• tiredness and sleepiness
• dizziness (lightheadedness)
• difficulty concentrating and memory problems
• confusion
• feeling unsteady on your feet
• feeling sick and vomiting
• double vision
• a reduced number of infection-fighting white blood cells (leukopenia)
• allergic skin reactions, such as urticaria (hives)

You should speak to your GP if you experience any persistent or troublesome side effects while you are taking carbamazepine, especially allergic skin reactions, as these could be dangerous.

Carbamazepine has also been linked to a number of less common but more serious side effects, including thoughts of self-harm or suicide. You should immediately report any suicidal feelings to your GP. If this is not possible, call the NHS 24 111 service.

Other medications

Carbamazepine may stop working over time. If this occurs, or if you experience significant side effects while taking it, you should be referred to a specialist to consider alternative medications or procedures.

There are a number of specialists you may be referred to for further treatment, including neurologists specialising in headaches, neurosurgeons and pain medicine specialists (for example, at a pain clinic).

In addition to carbamazepine, there are a number of other medications that have been used to treat trigeminal neuralgia, including:

• oxcarbazepine
• lamotrigine
• gabapentin
• pregabalin
• baclofen

None of these medications are specifically licensed for the treatment of trigeminal neuralgia, which means they have not undergone rigorous clinical trials to determine whether they are effective and safe to treat the condition.

However, this is largely only because trigeminal neuralgia is a rare condition, and clinical trials are difficult to carry out on such a painful condition because giving some people an inactive, “dummy” medication (placebo) to compare these medications to would be unethical and impractical.

However, many specialists will prescribe an unlicensed medication if they think it is likely to be effective and the benefits of treatment outweigh any associated risks.

If your specialist is considering prescribing an unlicensed medication to treat trigeminal neuralgia, they should inform you that it is unlicensed and discuss possible risks and benefits with you.

With most of these medications, the side effects can be quite difficult to cope with initially. Not everyone experiences side effects, but if you do, try to persevere because they do tend to diminish with time or at least until the next dosage increase, when you may find a further period of adjustment is necessary. Talk to your GP if you are finding the side effects unbearable.