Principles & Practice of Pain Medicine > Part V. Pain Syndromes > A. Neuropathic Pain > Chapter 39. Complex Regional Pain Syndrome Michael Stanton-Hicks

Complex Regional Pain Syndrome: Introduction

"Ever since Claude Bernard implicated the sympathetic nervous system in sensation, its role in nociception has been the subject of debate.¹ No one would argue with the fact that the sympathetic nervous system is intimately involved with the preservation of homeostasis and noxious challenges in humans, although the manner in which it influences the sensation of pain has, until recently, escaped explanation.² Anatomically, the sympathetic nervous system constitutes a highly complex arrangement of preganglionic and postganglionic neurons that subserve specific and diverse functions of target organs, including enteric neurons, smooth muscle, syncytial muscle, and striated muscle.³ Physiologically, the sympathetic nervous system is associated in some way with both systemic and specific local reactions, which are expressed by supratentorial and confrontational aspects that are represented in the periaquaductal gray matter of the midbrain (e.g., non-opioid analgesia).^4,5 In contrast, rest and quiescence are represented in the ventrolateral periaquaductal gray matter, being associated with endogenous opioid analgesia...."