Neuropathic Pain

Neuropathic pain is pain caused by a lesion or disease of the somatosensory nervous system. Unlike pain that signals ongoing tissue damage, it arises from the pain-signalling system itself being damaged or dysfunctional, and it is often described as burning, shooting, or electric-shock-like and accompanied by abnormal sensations.

Definition

Neuropathic pain is defined by the International Association for the Study of Pain as pain caused by a lesion or disease of the somatosensory nervous system, encompassing both peripheral and central neuropathic pain.

Scope

This topic covers the definition and grading of neuropathic pain, its characteristic clinical features and common causes, the peripheral and central mechanisms that generate it, and how it is distinguished from nociceptive and nociplastic pain. It is a reference overview of the syndrome, not clinical guidance on its management.

Key concepts

• Lesion or disease of the somatosensory nervous system
• Peripheral vs central neuropathic pain
• Allodynia and hyperalgesia
• Ectopic firing and peripheral sensitisation
• Central sensitisation
• Grading of neuropathic pain (possible, probable, definite)

Mechanisms

Neuropathic pain follows damage to or disease of the somatosensory system and is driven by maladaptive changes at several levels. After nerve injury, damaged and neighbouring neurons can become hyperexcitable and fire spontaneously (ectopic activity), and changes in ion-channel expression lower the threshold for firing. Persistent abnormal input drives central sensitisation in the spinal dorsal horn and higher centres, so that normally innocuous stimuli evoke pain (allodynia) and painful stimuli are amplified (hyperalgesia). Loss of inhibitory control and glial activation further sustain the state. These mechanisms help explain why neuropathic pain responds to different drug classes than nociceptive pain.

Clinical relevance

Neuropathic pain is common in conditions such as diabetic polyneuropathy, postherpetic neuralgia, nerve injury, and central lesions after stroke or in multiple sclerosis, and it tends to be more severe and harder to relieve than many other chronic pains. This entry describes the syndrome and its mechanisms as reference material and does not provide individualised diagnostic or treatment recommendations.

Epidemiology

Population estimates suggest that pain with neuropathic characteristics affects a substantial minority of adults, on the order of several percent, with the burden concentrated in conditions such as painful diabetic neuropathy and postherpetic neuralgia, as discussed in reviews underpinning treatment recommendations.

History

The concept of pain originating from the nervous system itself has long been recognised in conditions such as trigeminal neuralgia and causalgia. Over recent decades the definition was refined by the International Association for the Study of Pain to specify a lesion or disease of the somatosensory nervous system, and a formal grading system and an ICD-11 classification of chronic neuropathic pain were developed to standardise diagnosis and research.

Debates

How should neuropathic pain be graded in practice?

Distinguishing definite, probable, and possible neuropathic pain relies on combining the distribution of pain with confirmatory sensory or test findings, and applying these criteria consistently across diverse conditions remains a methodological challenge.

Key figures

• Nanna Finnerup
• Ralf Baron
• Joachim Scholz
• Rolf-Detlef Treede

Seminal works

• finnerup-2015
• treede-2015

Frequently asked questions

How does neuropathic pain differ from nociceptive pain?

Nociceptive pain results from activation of pain receptors by actual or threatened tissue damage, whereas neuropathic pain is caused by a lesion or disease of the somatosensory nervous system itself.

What are typical causes of neuropathic pain?

Common causes include diabetic polyneuropathy, postherpetic neuralgia, nerve trauma or compression, and central lesions such as those after stroke or in multiple sclerosis.