The neuronal response to pain

Abstract

A great deal of information has been obtained about the normal physiology of pain transmission. This information has been utilised in the development of techniques, such as transcutaneous electrical nerve stimulation and dorsal column stimulation, to relieve pain symptoms. This review will discuss the role of both the peripheral and the central nervous systems in the transmission of noxious stimuli. It will also discuss the neuronal response to pain involving spinal, thalamic and cortical neurons, as well as the descending inhibitory control systems. The response of peripheral and central neurons in pain models such as arthritis and peripheral neuropathy is altered. There is an increase in the neuronal response to peripherally applied stimuli following tissue or nerve injury that involves spinal, thalamic and cortical neurons. Increased activation of the endogenous descending inhibitory systems also occurs in response to injury. Both the peripheral and central nervous systems are ‘plastic', they can be modified and show considerable adaptation to injury. The severity of some diseases and injuries does not allow the body to control associated pain, resulting in chronic pain. Models of chronic pain syndromes are beginning to provide insight into the pathophysiology of injury and disease. Research in this area will hopefully provide better treatments for the chronic pain patient.