What is neuralgia?
Neuralgia is pain caused by nerve damage or irritation. The pain is typically intense and episodic, and often felt along the course of the affected nerve.
Neuralgia: causes and risk factors
Neuralgia is caused by nerve damage or irritation, which may be the result of a number of factors, including inflammation (neuritis), infection, physical irritation (e.g. compression) of a nerve, and faulty nerve nutrition. Tooth decay, poor diet, eye strain, nasal infections, diabetes, diseases of the nervous system such as syphilis and multiple sclerosis, anaemia, extreme cold, and certain toxins are also possible causes of neuralgia. In many cases, however, a cause cannot be found.
Neuralgia occurs most commonly in elderly people, but can occur at any age.
Types of neuralgia
There are many different types of neuralgia, including:
- Trigeminal neuralgia, or tic douloureux, involves the trigeminal nerve, which supplies sensation to the face. This is the most common form of neuralgia, affecting four to five per 100 000 people, almost always middle-aged or elderly. Sudden, brief (10 seconds or less) episodes of severe shooting pain occur on one side of the face - usually the lower face and jaw, and sometimes the forehead and temple. The pain may be severe enough to cause a facial tic (muscle spasm).
Certain movements, such as speech, chewing, swallowing or touching the face may trigger a neuralgia episode. The cause is occasionally identified as a blood vessel or small tumour compressing the nerve, inflammation of the nerve root, or disorders such as multiple sclerosis.
- Postherpetic neuralgia usually occurs as a complication of shingles, a painful rash that appears along the course of a nerve as a result of infection with the herpes zoster virus. A persistent, burning pain is felt at the site of a previous attack of shingles, one or more months after the rash. Movement or contact with the affected area worsens the pain.
This is the most common non-facial neuralgia (although it may also occur on the face). About 10% of people infected with herpes zoster develop neuralgia. In older adults, this figure may be up to 50%.
Neuralgias other than trigeminal neuralgia and postherpetic neuralgia are rare.
Symptoms of neuralgia may include:
- Pain, which is usually:
- superficial (on the surface of the body)
- brief and episodic (occurring at intervals, alternating with relatively pain-free periods), but may be severe
- occurring in the same location for subsequent episodes
- sharp and stabbing or constant and burning
- felt in the part of the body supplied by the affected nerve, and may be felt along the path of the nerve
- Usually no loss of function.
- Increased skin sensitivity.
- Any touch may be interpreted as pain.
- Movement may be painful.
How is neuralgia diagnosed?
Usually the diagnosis of a specific type of neuralgia is made when a doctor recognises characteristic features in patients' description of their symptoms. Important is the position of the pain (on one side of the face in trigeminal neuralgia, for example), its character, and factors that may trigger, worsen or relieve it.
A physical examination, and tests such as CT or MRI scanning, will also most likely be performed. The results of these will usually be normal in cases of neuralgia, but they are done to exclude other possible diagnoses.
How is neuralgia treated?
Treatment is aimed at pain relief, and varies depending on factors such as the cause (if known), location and severity of the neuralgia.
Medications used to treat neuralgia may include:
- Oral painkillers: Over-the-counter analgesics (painkillers) such as aspirin, acetaminophen and ibuprofen may be helpful for mild pain. However, non-narcotic painkillers are usually not strong enough for neuralgia pain, and narcotic analgesics such as codeine may be needed. (Narcotic drugs act to depress the central nervous system)
- Anticonvulsant drugs such as carbamazepine (Tegretol), gabapentin (Neurontin) or phenytoin (Dilantin) may ease trigeminal neuralgia.
- Antidepressant medications, such as the tricyclic amitriptyline (Elavil) may help to control pain, usually in cases of post-herpetic neuralgia.
- Ointments: over-the-counter topical painkillers, such as capsaicin (Zostrix) and lidocaine (Xylocaine) preparations.
- Antiviral agents: some experts think that trigeminal neuralgia may be alleviated with acyclovir or related antiviral medications. Post-herpetic neuralgia may possibly be associated with a persistent active virus, and therefore antiviral treatment might be helpful.
- Steroid medications are also sometimes used in neuralgia treatment.
Surgical and other methods of treatment
Treating a known cause of neuralgia may include surgery to remove tumours or separate the nerve from blood vessels or other structures compressing it.
If no cause can be found, and pain cannot be relieved by other methods, in severe cases the following methods may be considered:
- Nerve block: injection of medication (such as Novocaine or alcohol) to temporarily deaden nerves.
- Rhizotomy surgery: cutting the nerve roots to replace severe pain with numbness.
- Radiofrequency ganglio-neurectomy: involves deadening a nerve by "cooking" it with microwaves.
- Gamma-knife "surgery": deadening a nerve by "cooking" it with gamma radiation.
- Dorsal root zone (DREZ) surgery: destroys the area where damaged nerves join the spinal cord, thus interrupting pain messages to the brain.
- Transcutaneous electrical nerve stimulation (TENS): Electrodes placed over the painful area deliver a mild electrical impulse to nearby nerve pathways, easing pain.
Physical therapy may be helpful for some types of neuralgia, especially postherpetic neuralgia.
What is the outcome of neuralgia?
Most neuralgias are not life-threatening and do not indicate underlying life-threatening disorders. However, neuralgia pain can be severe and sometimes disabling.
Effectiveness of treatment depends on the cause of the neuralgia, but most cases do respond to pain relief.
Some people may have to live with neuralgia for the rest of their lives, and attacks may become more frequent with age. In other cases, the condition gradually fades away.
Can neuralgia be prevented?
Most cases of neuralgia cannot be prevented. Treatment of associated disorders may or may not prevent its development.
Anti-viral treatment of shingles within three days of developing the rash can ease the severity of the infection and minimise the risk of developing postherpetic neuralgia.
When to call the doctor
Consult your doctor if you experience symptoms of neuralgia, especially if these are prolonged or unrelieved by over-the-counter analgesics.
(Reviewed by Dr Andrew Rose-Innes, Department of Neurology, Yale University School of Medicine)