Pain Pathways

Chapter 1 describes the anatomic organization of the nervous system elements dedicated to sensing and perceiving pain: the so-called pain pathways or nociceptive processing system. This is a small part of the human nervous system that has a large impact on self-preservation as well as the potential to attenuate quality of life. The pain system is divided into four functional subsystems: transduction, dedicated to encoding information about noxious stimuli into the form of action potentials; transmission, which functions to carry pain information from distal structures such as toes to the spinal cord and brain; perception, which engages multiple areas of the cortex as well as subcortical structures to create an integrated awareness of pain; and modulation, which involves several different brain and spinal structures to potentially increase and decrease sensitivity and responses to painful stimulation. The development of the pain system is discussed in detail. This chapter provides the foundation for Chapter 2, which focuses on the relevant neurotransmitters and molecular signaling events involved in the major aspects of pain system functioning. Understanding pain structural pathways will often provide unique insight into a patient’s pain experience, provide clues regarding the cause of a patient’s pain, and yield insights into potentially effective treatments.