Neuropathic Pain

What is it?

The International Association for the Study of Pain (IASP) defines neuropathic pain as "pain caused by a lesion or disease of the somatosensory nervous system", the part of the nervous system that carries sensations such as touch, temperature and pain. Put simply, in neuropathic pain the problem lies not in the tissue where the pain seems to start, but in the nervous system that carries or processes the pain signal.

The damage may be in the brain and spinal cord (central neuropathic pain) or in the nerves that branch out through the body (peripheral neuropathic pain). Neuropathic pain is often long-lasting, affects sleep and mood, and responds only partly to standard painkillers.

What causes it?

The main conditions that cause neuropathic pain are:

• Diabetic neuropathy: nerve damage, particularly in the feet and legs, caused by blood sugar levels that have been high for a long time.
• Post-herpetic neuralgia: nerve pain that persists in the same area after shingles (herpes zoster).
• Nerve root compression: arm or leg pain caused by a disc herniation in the neck or lower back, or by spinal stenosis (sciatica).
• Trigeminal neuralgia: electric-shock-like attacks of facial pain (headache and facial pain).
• Nerve damage after surgery or injury: pain persisting around a surgical scar, and phantom limb pain felt in an amputated limb.
• Chemotherapy-induced neuropathy and nerve involvement by cancer.
• Central causes: pain that develops after a stroke, a spinal cord injury or multiple sclerosis.

Vitamin B12 deficiency, excess alcohol, thyroid disease and some medicines can also damage nerves. Complex regional pain syndrome (CRPS), which usually follows an injury or operation and causes more severe pain than expected in an arm or leg, together with swelling and changes in skin colour and temperature, is assessed and treated with similar methods.

How is it diagnosed?

Diagnosis is based on a detailed history, the way the pain is described and a neurological examination. Pain that follows the territory of a nerve or nerve root, together with changes in sensation in that area, supports neuropathic pain. Short questionnaires designed to screen for neuropathic pain can also help.

To find the underlying cause, blood tests such as blood sugar, vitamin B12 and thyroid function, nerve conduction studies and EMG, and an MRI where needed, are arranged. Identifying the cause matters, because in some cases treating it can slow the progression of nerve damage.

Treatment options

The aim of treatment is to bring the pain down to a level you can live with and to improve sleep and daily function. Treatment usually combines several approaches.

Conservative care

• Treating the cause: for example, controlling blood sugar in diabetes or correcting a vitamin deficiency.
• Medication: instead of standard painkillers, certain antidepressants and anti-epileptic medicines that can act on nerve pain are used. They are started at a low dose and increased gradually, and their effect builds up over several weeks. For pain in a limited area, medicated plasters or creams may be used.
• Physiotherapy and exercise: to maintain mobility and reduce oversensitivity.
• Psychological support: to help build coping skills and to address sleep and mood problems.

Interventional pain treatments

For people who do not get enough relief from medication, or who cannot tolerate its side effects, interventional methods are considered:

• Sympathetic nerve blocks: in complex regional pain syndrome and in the early stages of shingles, procedures such as a stellate ganglion block or a lumbar sympathetic block can reduce pain and make it easier to take part in rehabilitation.
• Radiofrequency treatment: pulsed radiofrequency can be applied when pain comes from a specific nerve or nerve root.
• Spinal cord stimulation: for long-standing neuropathic pain that has not responded to other treatments, thin electrodes placed over the spinal cord are used to modify pain signals. A trial period is carried out before the main procedure in which the battery and electrodes are implanted.

In suitable patients these methods can provide a meaningful reduction in pain, but results vary from person to person and each procedure carries its own risks.

When is surgery considered?

If there is a correctable cause pressing on a nerve, such as a disc herniation, spinal stenosis or nerve entrapment, surgery is assessed with a neurosurgeon.

When should you see a doctor?

See a doctor if burning, shooting or tingling pain has lasted more than a few weeks or disturbs your sleep, or if your current medicines are not working well enough or are causing side effects. An algology (pain medicine) specialist will assess the neuropathic features of the pain and its cause, and plan medication and interventional options with you; you can request an appointment through our contact page.