New physiological classification of pains: current concept of neuropathic pain

ABSTRACT BACKGROUND AND OBJECTIVES Neuropathic pain is a complex entity and experts have tried to define it in a clearer and more objective way for its diagnosis to be more accurate, especially for non-specialists. Aiming at evaluating studies on the subject and their repercussion on medical practice, a systematic review was carried out from 2000 to 2016 on published studies about neuropathic pain, its definition and involved physiological aspects, using Pubmed, Cochrane and LILACS as databases. CONTENTS The new concept accepted by the International Association for the Study of Pain in 2011 considers neuropathic pain as "pain induced by injury or disease directly affecting the somatosensory system". So, "dysfunction", considered a vague term, was replaced by "disease", and "nervous system was replaced by "somatosensory system", to topographically delimit the disease. The new definition has created diagnoses based on clinical history and anatomic location, associated to evidential tests. Conditions such as diabetic polyneuropathy, post-herpetic neuropathy, compressive radiculopathy, other peripheral neuropathies and thalamic pain were well covered by new guidelines, however pains such as essential trigeminal neuralgia, fibromyalgia, complex regional pain syndrome type I, were excluded from the new definition. CONCLUSION Current concept is not ideal; it is limited and excludes major pain states and although the new classification has improved the understanding of neuropathic pain, further studies are needed on the subject.