Neuropathic pain.

Neuropathic pain refers to pain that originates from pathology of the nervous system. Common causes of neuropathic pain are diabetes mellitus, reactivation of herpes zoster, nerve compression or radiculopathy, alcohol, chemotherapy or abuse of some drugs, and trigeminal neuralgia. Specific symptoms of neuropathic pain are mechanical allodynia and cold hyperalgesia. Drugs to treat neuropathic pain can be divided into adjuvant analgesics (antidepressants and anticonvulsants), opioids and topical agents. The use of multiple drug therapies is common in practice. Despite considerable increase in the number of randomized placebo-controlled trials in neuropathic pain in the last few years, the medical treatment of neuropathic pain is still far from being satisfactory, with less than half of patients achieving significant benefit with any pharmacological drug.