Altered cortical morphology in patients with chronic shoulder pain

Shoulder pain is a common condition associated with slow recovery and high recurrence rates. Persistent pain may lead to structural brain changes that may further promote pain chronification. The present study addressed whether abnormal changes in cortical surface structure exist in patients with chronic shoulder pain of myofascial origin and whether such changes would be related to pain measures. Brain structural MRIs were obtained in 22 patients with chronic pain in the bilateral upper trapezius muscles and in 22 healthy controls. Cortical thickness, gyrification index and sulcal depth were assessed together with pain measures. Shallower sulcal depth was found in patients in the right central sulcus, posterior insula, inferior frontal and dorsomedial prefrontal cortices, precuneus, and the middle temporal cortex, and in the left medial orbitofrontal cortex. Negative correlations were found between the right central sulcus and pain intensity and between the left medial orbitofrontal cortex and pain affect. Cortical thickness or gyrification index did not differ significantly between the two groups. The afflicted cortical regions constitute interacting networks responsible for sensory, affective and cognitive dimensions of the pain experience.