Neuralgia

Neuralgia is the name given to severe pain coming from a nerve. There are two types of neuralgia, trigeminal neuralgia and postherpetic neuralgia.

Trigeminal neuralgia

Trigeminal neuralgia is sudden, severe facial nerve pain. It can be described as a "stabbing", "shooting" or "electric-shock-like" pain in the face, which can last for a few minutes at a time.

In most cases, trigeminal neuralgia only affects one side of the face, with just 3% of people with the condition experiencing pain on both sides of their face.

Trigeminal neuralgia is quite a rare condition. For example, in the UK it is thought to affect only four or five people out of 100,000 each year. However, since it can sometimes be difficult to confirm a diagnosis of neuralgia, this figure may be considerably higher.

Almost twice as many women are affected by trigeminal neuralgia as men. Trigeminal neuralgia becomes more common with age, and is rare among people below the age of 40.

Trigeminal neuralgia is a chronic condition that often gets worse over time. The symptoms can be treated with medicines to ease the pain, although in some cases surgery may be needed.

Postherpetic neuralgia

Postherpetic neuralgia is constant severe nerve pain that can sometimes occur as a result of shingles.

Shingles is an infection caused by a virus called varicella zoster, which is the virus that also causes chickenpox. It usually affects the nerves of the chest and abdomen, causing pain and a rash on one side of the body.

In most cases, shingles lasts between two and four weeks. If the pain caused by shingles continues for longer than this after the rash has healed, it is known as postherpetic neuralgia.

In adults, postherpetic neuralgia is the most common complication of shingles. However, it is difficult to estimate how many people are affected by the condition because there are many varying definitions of the condition in terms of the time it takes to develop and the length of time that someone experiences pain. Research has estimated that approximately 20% of people with shingles will go on to have postherpetic neuralgia.

This type of neuralgia is uncommon in children, but the risk of developing it increases with age.

Postherpetic neuralgia sometimes resolves after a few months, although the symptoms can last longer than this. Medicines and treatments are available that can ease the symptoms, but they may not relieve the pain completely.

Neuralgia is severe nerve pain. The type of pain, and where it occurs, depends on the type of neuralgia that you have.

Trigeminal neuralgia

The symptoms of trigeminal neuralgia may include:

• severe stabbing or piercing pain in your face that comes on suddenly, usually around your cheek or jaw area,
• severe pain in your forehead or around your eyes,
• pain on one side of your face, although in rare cases you may have pain on both sides,
• tingling or numbness in your face before the pain develops,
• spasms of pain that may last from a few seconds to two minutes each time.

If you have trigeminal neuralgia, you may experience spasms of pain regularly for days, weeks or months at a time. In severe cases you may experience the pain hundreds of times a day. However, it is also possible for the pain to disappear completely and not reoccur again for months or even years.

You may also have points on your face that if touched, even gently, will bring on pain. Certain actions or movements can also trigger the pain, such as speaking, eating and washing your face.

Living with trigeminal neuralgia can be very difficult. You may feel like avoiding activities such as washing, shaving or eating, in order to try to prevent the pain from coming on.

Postherpetic neuralgia

The symptoms of postherpetic neuralgia can include:

• constant burning, aching, or throbbing pain at the places on your body where your shingles occurred,
• occasional stabbing or shooting pain, and
• intense itching.

If you have postherpetic neuralgia you may find that your pain is made worse by heat or cold, or that something that would normally only cause mild pain, such as bumping your arm, is very painful.

Like trigeminal neuralgia, postherpetic neuralgia can interfere with your ability to carry out some daily activities such as dressing and bathing. You may also have trouble sleeping and experience fatigue.

The two types of neuralgia - trigeminal neuralgia and postherpetic neuralgia - are caused in different ways.

Trigeminal neuralgia

Trigeminal neuralgia comes from the trigeminal nerve. You have two trigeminal nerves in your face; one in each side. Each nerve splits into three branches, which between them transmit sensations of pain and touch from your face, teeth, and mouth to your brain.

The causes of trigeminal neuralgia are not completely understood. In some cases, it may not be possible to identify a cause.

However, in 80-90% of cases, trigeminal neuralgia is thought to be caused by blood vessels pressing on the root of the trigeminal nerve (where the nerve leaves your brain).

It is thought that the pressure that is placed on the trigeminal nerve causes uncontrollable pain signals to travel along the nerve to your face, causing the sudden stabbing pains of trigeminal neuralgia.

Other, less common causes of trigeminal neuralgia include pressure on the trigeminal nerve from a tumour and multiple sclerosis (a long-term condition that affects the central nervous system).

In multiple sclerosis, the nerve fibres of your central nervous system become damaged due to the body's own immune system, which can also affect the trigeminal nerve.

Postherpetic neuralgia

Postherpetic neuralgia is where the nerve damage caused by shingles prevents the nerves from working properly. The damaged nerves send uncontrolled pain signals to your brain, resulting in a burning, throbbing pain at the site of the nerves.

It is not clear why some people who have shingles go on to develop postherpetic neuralgia after the shingles infection has gone.

However, it is possible that the nerve damage that is caused by shingles leads to scar tissue forming next to the nerves. The scar tissue may press on the nerves and cause them to send involuntary pain signals to your brain.

See your GP if you think that you may have trigeminal neuralgia or postherpetic neuralgia after a bout of shingles. Your GP will ask you about your symptoms and they may carry out some tests.

Diagnosing trigeminal neuralgia

If your symptoms suggest that you have trigeminal neuralgia your GP will need to examine your face to find out exactly which parts are painful.

They may also need to rule out several other conditions that can cause severe pain in your face, such as severe tooth decay and infection of your sinuses (the small, air-filled cavities inside your cheekbones and forehead).

If your GP needs to rule out other conditions in order to confirm a diagnosis of neuralgia you may need to have a magnetic resonance imaging (MRI) scan. An MRI scan uses a strong magnetic field and radio waves to create detailed images of the inside of your brain and the trigeminal nerve.

As well as being able to confirm a diagnosis of trigeminal neuralgia an MRI scan can also show whether trigeminal neuralgia is caused by another condition, such as multiple sclerosis (a chronic condition that affects the central nervous system).

Diagnosing postherpetic neuralgia

If you have had shingles, your GP will be able to base a diagnosis of postherpetic neuralgia on your symptoms and the length of time that you have had them.

Postherpetic neuralgia is easy to diagnose because it only occurs as a complication of shingles.

The main aim of treatment for neuralgia is to control the pain. There are many different medicines and treatments that are available to help achieve this.

The two different types of neuralgia - trigeminal neuralgia and postherpetic neuralgia - are treated in different ways.

Treatment for trigeminal neuralgia

If you have trigeminal neuralgia, your GP will first prescribe a type of medicine called an anticonvulsant, which can help relieve or numb the pain in your face.

Anticonvulsants

Normal painkillers such as paracetamol are not effective in treating trigeminal neuralgia, so your GP may prescribe an anticonvulsant medicine (a medicine that is often used to prevent seizures). Anticonvulsants that are sometimes used to treat trigeminal neuralgia include carbamazepine and gabapentin.

Although anticonvulsant medicines are usually used to treat epilepsy, they can be effective in treating trigeminal neuralgia because they calm down nerve impulses. If one type of anticonvulsant does not work for you, your GP may prescribe another or they may alter your dose.

In some cases, anticonvulsants can cause several side effects, such as:

• drowsiness,
• dizziness, and
• nausea and vomiting.

Anticonvulsants have also been linked to an increased risk of thoughts of self-harm or suicide. Therefore, you may be closely monitored if you are prescribed one.

If you are of Asian descent you may need to have a blood test before you can take carbamazepine. This is because carbamazepine can cause a severe rash in people with a particular genetic type. And, most people with this type of gene originate from Asia.

It is also possible for anticonvulsants for trigeminal neuralgia to stop working over time because they are only effective in numbing the pain and not stopping the cause of it. If this occurs you may be referred for specialist treatment.

You may also be referred for specialist treatment for trigeminal neuralgia if:

• you have pain in your face between spasms of trigeminal neuralgia,
• any of your senses are affected,
• anticonvulsants are not effective in controlling your pain,
• anticonvulsants cause you to experience severe side effects, or
• you are under 40 years of age.

You may receive specialist treatment for trigeminal neuralgia from a neurologist (a specialist in conditions of the central nervous system), a specialist in treating pain, or a neurosurgeon (an expert in surgery of the brain and nervous system).

Surgery

If anticonvulsants do not ease your pain or if they cause severe side effects, your GP may suggest that you have surgery.

The aim of surgery for trigeminal neuralgia is to either stop your blood vessels from putting pressure on the trigeminal nerve, or to damage the nerve just enough to stop if from malfunctioning. There are several operations that can achieve these aims. Your surgeon should fully explain the options with you.

Microvascular decompression

In most cases, the most effective operation for trigeminal neuralgia is an operation called microvascular decompression. This operation releases the pressure of blood vessels that are pressing on the trigeminal nerve.

During microvascular decompression surgery, your surgeon will either remove or relocate the blood vessels, separating them from the trigeminal nerve.

For most people, microvascular decompression surgery is very effective in easing the pain of trigeminal neuralgia. However, the operation can sometimes cause complications including damage to your hearing in one ear, facial weakness, and double vision.

Stereotactic radiosurgery

Stereotactic radiosurgery uses a concentrated beam of radiation to reduce the effectiveness of the trigeminal nerve. Stereotactic radiosurgery is a type of 'gamma-ray knife surgery' because it does not require any anaesthetic or incisions (cuts) to be made in your skin.

As stereotactic radiosurgery is still a fairly new treatment, your surgeon will discuss exactly what is involved with you before your operation. So far, this treatment has been found to be quite effective for trigeminal neuralgia, although it can take several weeks before the pain eases. Stereotactic radiosurgery may sometimes cause facial numbness, or tingling.

Other types of surgery for trigeminal neuralgia

Other types of surgery that you may have for trigeminal neuralgia are outlined briefly below.

• Nerve block - where anaesthetic is injected into your face over several weeks or months.
• Cryotherapy - where the trigeminal nerve is frozen using chemicals.
• Alcohol injections - which are given into the ends of your nerves to numb your pain.
• Glycerol injection - which is injected where the three branches of the trigeminal nerve join.
• Neurectomy - a procedure where the ends of your nerves are cut.
• Peripheral radiofrequency thermocoagulation - where radiation is used to damage the nerve endings.
• Balloon compression - where a tiny balloon is inflated over the trigeminal nerve in order to relieve pressure.
• Electric current - where an electric current is used to numb the trigeminal nerve.

Treatment for postherpetic neuralgia

If you have postherpetic neuralgia, your GP will usually recommend or prescribe a painkiller to help ease the pain of your condition.

Painkillers

The type of painkiller that your GP recommends or prescribes for you will depend on the severity of your symptoms. However, your first painkiller is likely to be paracetamol. If paracetamol alone does not help to ease your pain you may also be prescribed a stronger painkiller called codeine to take alongside it.

Antidepressants

If a combination of paracetamol and codeine is not enough to keep your pain under control, your GP may prescribe a type of tricyclic antidepressant. This is not because they think you are depressed, but because this type of antidepressant can be used to ease the pain of postherpetic neuralgia.

Tricyclic antidepressants work on certain chemicals in your brain that react to pain and can make them less sensitive. These medicines can help to significantly improve your pain, although they may not be able to ease it completely.

If you are prescribed a tricyclic antidepressant it is likely to be amitriptyline, imipramine or nortriptyline. They may cause side effects, such as a dry mouth and drowsiness. However, as antidepressants for postherpetic neuralgia are prescribed at a lower dose than they are for depression, any side effects that you experience should only be mild.

Anticonvulsants

Tricyclic antidepressants may not be suitable for everyone who has postherpetic neuralgia. If paracetamol and codeine do not control your pain, but you cannot take tricyclic antidepressants, you may be prescribed an anticonvulsant medicine called gabapentin.

Although anticonvulsant medicines are usually used to treat epilepsy, they can also be effective in treating postherpetic neuralgia because they calm down nerve impulses. Gabapentin may cause side effects such as drowsiness, dizziness and muscle weakness.

Capsaicin cream

If simple painkillers are not effective in treating the paint that is caused by neuralgia, and both antidepressants and anticonvulsants are not suitable for you, your GP may suggest capsaicin cream for additional pain relief.

Capsaicin cream works by blocking the nerves that send pain messages. However, you may have to use it for a while before it has an effect. You should experience some pain relief within the first two weeks of using the cream but it may take up to a month before the treatment is fully effective.

After applying capsaicin cream, you may experience a burning sensation on your skin. This is nothing to worry about and the more you use the cream, the less you will notice it. However, avoid using too much capsaicin cream or having a hot bath or shower before or after applying it because it may make the burning sensation worse.

Lidocaine patches

If you are unable to tolerate the medications that are usually used to treat postherpetic neuralgia, such as tablets or creams, your GP may recommend using lidocaine patches.

Lidocaine patches contain a local anaesthetic, which has a painkilling effect on the area to which the plaster is applied. Make sure that you follow the instructions that come with the lidocaine patches when applying them to your skin.

Neuralgia can sometimes be triggered or made worse by a number of different things. You may be able to ease the pain of neuralgia by trying to avoid these triggers as much as possible.

Trigeminal neuralgia

Avoid wind and draughts

You may find that your pain is triggered by wind or even by a draught in a room. If this is the case, avoid sitting near open windows or the source of air conditioning and wear a scarf wrapped around your face during windy weather.

Be wary of heat and cold

Anything that is hot or cold may trigger your pain, so try not to eat or drink anything that is either very hot or very cold. You could also try using a straw to drink warm or cold drinks in order to help prevent the liquid from coming into contact with the painful areas of your mouth.

Postherpetic neuralgia

Wear comfortable clothing

If you have postherpetic neuralgia, wearing clothes that are too tight or made of rough or synthetic material may irritate your skin and make your symptoms worse. Instead, wearing loose cotton clothing will usually cause less irritation.

Cover sensitive areas

You may find that some areas of your skin are more affected by postherpetic neuralgia than others. If your clothes tend to rub in certain areas try covering them with a plastic wound dressing or cling film.

Use cold packs

Unless your postherpetic neuralgia is made worse by cold, you could try using gel-filled cold packs in order to numb your pain. Simply place them in the freezer to cool them down before pressing them gently against your skin.

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