الفهرس 
The Pain PathwayOnly 14 pages are availabe for public view
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Abstract
The highest incidence of chronic post-surgical pain follows a variety of surgical procedures, including limb amputation, thoracotomy, mastectomy, hernia repair, open cholecystectomy, cesarean section, hip replacement and median sternotomy (for coronary artery bypass graft surgery).
A four-point definition has been proposed of Persistent Post-Surgical Pain (PPSP). Postoperative pain qualifies as chronic if: the pain has emerged as a consequence of surgery; its duration is at least two to three months; no other explanation exists for the pain and the pain is not a continuation of a preexisting chronic pain condition for which the surgery was performed.
Several theoretical frameworks have been proposed to explain the physiological basis of pain. The Gate Control Theory is the cornerstone while discussing the anatomy of the pain pathway. Other theories demonstrated that in chronic pain conditions, brain structure and function undergo plasticity proving that cognitive effects can alter sensory discrimination.
Primary afferent nociceptors send a peripheral axon to innervate the skin and a central axon to synapse on second-order neurons in the dorsal horn of the spinal cord or the trigeminal nucleus. They transmit to the somatosensory cortex via the thalamus. Other projection neurons engage the cingulate and insular cortices via connections in the brainstem and amygdale. This ascending information also accesses neurons of the rostral ventral medulla and midbrain periaqueductal gray to engage descending feedback systems that regulate the output from the spinal cord.