Neuroplasticity and pain: what does it all mean?

he concept of neuroplasticity — the ability of the nervous system to change its structure and function — has captured the imagination of clinicians, researchers and the general public. 1 The ability of the brain to reorganise itself is remarkable. For example, people who are visually impaired engage their visual cortex for fine sensory discrimination when using their hands. In these situations, neuroplasticity appears to be a positive adaptation to loss of function. Recent neuroplasticity studies have shown that pain is associated with a host of functional, anatomical and chemical changes at many levels of the nervous system. 2,3 The most intriguing and dramatic example of functional changes is the reorganisation that occurs at a cortical level, particularly in association with major trauma to the nervous system such as limb amputation or spinal cord injury. 4,5 In these situations, it has been shown that regions of the cortical homunculus that normally respond to inputs from a part of the body that has been denervated can be activated by stimuli that would normally activate an adjacent region of the sensory cortex. For example, stimulation of the lip in people with an amputated arm will activate the lip region as well as the adjacent sensory cortex normally activated by inputs from the hand. This reorganisation has been shown to be important in pain medicine. Although the direction of causality is unclear, the reorganisation is strongly linked to the presence of pain. Therefore, neuro-plasticity may be an attempt by the nervous system to adapt to injury in a positive way. But in the case of pain, neuroplasticity appears to be maladaptive. Chemical and structural changes which occur in the presence of pain and injury include receptor and neuro-transmitter changes that flow through to physiological phenomena such as alterations in pain modulation 6,7 and sensitisation of central neurones involved in the transmission of nociceptive signals. 3,8 These changes amplify signals arising from tissue damage and can increase the intensity of experienced pain. Understanding neuroplasticity has put paid to the old concept that pain is merely another sensation transmitted along hard-wired pathways. Findings regarding the complexity of pain processing, including neuroplasticity, show that the experience of pain engages an entire orchestra of pathophysiology. This means that the best chance of success in treating pain occurs when assessment and treatment address these many factors. For example, treating persistent low back pain means not just trying to …