Spontaneous pain and brain activity in neuropathic pain: functional MRI and pharmacologic functional MRI studies.

Functional brain imaging studies in chronic neuropathic pain patients have lagged far behind equivalent studies in acute pain. In the past few years, this trend has begun to shift. This article discusses the novel approach of studying brain activity for spontaneous pain and its modulation by pharmacologic manipulation. We argue that the approach provides a solid methodology for studying clinical (especially neuropathic) pain and patient populations, and moreover, that the latest results using this approach imply that distinct clinical chronic pain conditions seem to involve specific brain circuitry, which is also distinct from the brain activity commonly observed in acute pain.