Neuropathic Pain
Definition
The International Association for the Study of Pain (IASP) defines neuropathic pain as “Pain initiated or caused by a primary lesion or dysfunction in the nervous system.” It is characterized by spontaneous and or abnormal stimulus-evoked pain (1)
This type of pain, is not nociceptive in nature and nonprotective, persists independent of ongoing tissue injury or inflammation (2).
Alterations in sensation are commonly described in neuropathic pain. These can range from simple hypoaesthesia or numbness to abnormal noxious sensations such as burning (dysaesthesia).
Clinically simple touch becomes a painful stimulus (allodynia), painful responses become magnified (hyperalgesia) and responses to relatively innocuous stimuli are prolonged and exaggerated (hyperpathia). (3)
Children can describe this pain as burning, sharp, shooting (lancinating) or stabbing.
In daily practice neuropathic pain is regularly seen in patients with cancer due to nerve compression or direct invasion from the tumor itself or its metastasis.
Causes:
Table: Causes of neuropathic pain
Central
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Neurodegenerative conditions
Tumor compression
Raised intracranial pressure
Neuro-irritability
Spinal cord injury/compression
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Peripheral |
Traumatic (including iatrogenic) nerve injury
Postsurgical peripheral neuropathic pain
Phantom limb pain
Polyneuropathies:
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Cancer related neuropathy |
Tumor invasion
Radiation
Chemotherapy : vinca alkaloid induced neuropathy
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