The most widely accepted definition today is that given by the International Association for the Study of Pain: “Pain is an unpleasant sensory or emotional experience associated with actual or potential tissue damage, or described in terms of such damage”. In fact it is a defence mechanism against greater damage, although it often has an impact on quality of life. Pain is a common disorder. In Spain it is estimated that more than 17% of the adult population suffer from some type of pain.

Neuropathic pain is caused by the abnormal functioning of the nervous system, which mistakes stimuli such as temperature or touch for painful stimuli. It may indicate the poor functioning of some areas of the nervous system and has several types of manifestation (post-herpetic pain, diabetic neuropathies, trigeminal neuralgias, etc.).