Peripheral and central mechanisms of pain from incision differs from inflammatory or chronic pain. It is expected that brain activation patterns differ with pain type but have not been studied in humans. In this study, the activation of different brain areas after an experimental surgical incision was assessed by functional magnetic resonance imaging, and the pathophysiological role of distinct brain activation patterns for pain perception after incision was analyzed. Functional magnetic resonance imaging analysis showed a distinct temporal profile of activity within specific brain regions during and after the injury. Lateralization (predominantly contralateral to the incision) and increased brain activity of the somatosensory cortex, frontal cortex, and limbic system were observed in subjects after incision, when compared with individuals receiving sham procedure. Peak brain activation occurred about 2 min after incision and decreased subsequently. Basal ganglia structures and especially the caudate nucleus were activated shortly after incision. Lateron activity persists in neocortical structures, but was absent in basal ganglia structures. A distinct correlation between evoked pain ratings and brain activity was observed for the anterior cingulate cortex, insular cortex, thalamus, frontal cortex, and somatosensory cortex. These findings show different and distinct cortical and subcortical activation patterns over a relevant time period after incision. Pain sensitivity hereby has an influence on the activity profile. This may have important implications for encoding ongoing pain after a tissue injury, for example, resting pain in postoperative patients.

Pogatzki-Zahn, E.M., Wagner, C., Meinhardt-Renner, A., Burgmer, M., Beste, C., Zahn, P. K., & Pfleiderer, B., Coding of incisional pain in the brain: a functional magnetic resonance imaging study in human volunteers, Anesthesiology, 2010, 112: 406-417.