Impaired default mode network activity in cancer pain patients

The mechanism of chronic cancer pain has yet fully elucidated even though nearly 80% of cancer patients suffer from chronic pain. We investigated the difference in brain activities between painful and painless cancer patients from 103 FDG-PET brain images of the head-neck or esophageal cancer patients. Painful cancer patients showed enhanced activity in the bilateral amygdala, hippocampus, and pons, and inhibited activity in the precuneus and middle cingulate gyrus relative to the painless patients. The metabolic connectivity related to the above regions showed a significant relationship with brain regions associated with the default mode network (DMN) in the painful cancer patients, while no significant metabolic connectivity to the DMN regions was found in the painless patients. These results indicate that in cancer pain patients, chronic pain may increase limbic system activity and affect the DMN, leading to changes in the cognition of pain and visceral sensation.