Do we need a third mechanistic descriptor for chronic pain states?

1. Introduction The redefinition of neuropathic pain,23 which specifically excludes the concept of “dysfunction,” has left a large group of patients without a valid pathophysiological descriptor for their experience of pain. This group comprises people who have neither obvious activation of nociceptors nor neuropathy (defined as disease or damage of the somatosensory system) but in whom clinical and psychophysical findings suggest altered nociceptive function. Typical such patient groups include those labelled as having fibromyalgia, complex regional pain syndrome (CRPS) type 1, other instances of “musculoskeletal” pain (such as “nonspecific” chronic low-back pain), and “functional” visceral pain disorders…