Which statements correctly describe the three main categories of pain and their mechanisms?

• A. Nociceptive pain arises from tissue injury activating peripheral nociceptors; neuropathic pain stems from injury or dysfunction within the nervous system causing ectopic activity and sensitization; centralized (functional) pain involves altered central processing and amplification of pain signals without ongoing peripheral pathology.
• B. Nociceptive pain arises from central nervous system dysfunction; neuropathic pain results from psychological factors; centralized pain is due to peripheral nerve injury only.
• C. Neuropathic pain results from ongoing tissue inflammation; nociceptive pain arises from nerve damage; centralized pain is due to increased pain threshold.
• D. Nociceptive pain and neuropathic pain both require ongoing tissue injury; centralized pain is a subset of neuropathic pain with spinal changes.

Answer: (A)