Brain damage in certain areas has been seen in chronic back pain, Complex Regional Pain Syndrome, Fibromyaglia, and so on. The question is whether the damage causes the pain or visa versa. In hip pain patients, the at least partial resolution of this atrophy following successful hip surgery suggests the pain causes the damage.
- 32 cases of chronic Osteoarthrtis of hip showed “a characteristic gray matter decrease in:
- anterior cingulate cortex (ACC) – chronic pain center
- right insular cortex and operculum – pain severity monitoring centre
- dorsolateral prefrontal cortex (DLPFC) – happiness and hence depression centre
- amygdala – emotional home
- brainstem – pain relay station
- 10 cases were followed post hip surgery and demonstrated “a gray matter increase in the DLPFC, ACC, amygdala, and brainstem”
- Their conclusion was that ” As gray matter decrease is at least partly reversible when pain is successfully treated, we suggest that the gray matter abnormalities found in chronic pain do not reflect brain damage but rather are a reversible consequence of chronic nociceptive transmission, which normalizes when the pain is adequately treated.”
Comment – Given that brain damage in the DLPFC will cause depression (seen in subjects treated with Inferon injections for Hep C treatment), it can be concluded that the depression seen in chronic pain is more likely the response to chronic pain, albeit those with depression tendencies are likely to fall prey to it faster.