The International Association for the Study of Pain has defined “neuropathic pain” as a pain that is caused by a “lesion” or “disease” of the somatosensory nervous system. It can be caused by a wide variety of insults, with resulting peripheral and central sensitization, as well as responses in the neuroimmune system.

Diagnosis of neuropathic pain requires detailed history, physical examination and relevant investigations to look for lesions in the somatosensory nervous system, and a search for the underlying causes. Hyperalgesia, allodynia, hyperpathia and dysesthesia can be commonly elicited in patients with neuropathic pain. A pain diagram is useful in visualizing the distribution of pain. Electrophysiology studies help differentiate lesions in different types of nerve fibres. Imaging studies are useful for locating structural lesions. Laboratory tests may be indicated to look for the underlying cause of neuropathy.

As the presentation of neuropathic pain may vary considerably and most patients will first present to their general practitioners, a simple tool to aid the diagnosis will be useful. A number of screening tools for neuropathic pain are available. A Chinese version of the ID-PainTM questionnaire has just been validated for local patients.