Acute and chronic pain arise from different processes and are approached very differently. While acute pain is a physiological response to a known stimulus, and disappears with tissue healing, chronic pain is not necessarily related to tissue damage, and therefore persists due to changes or damage in the neuronal pathways that relay pain. For acute pain, the pain is expected to be greatest immediately following the noxious stimulus (e.g. surgery), and so pain control is initially high and is titrated down as the tissue heals. Chronic pain management aims to titrate up pain control measures, starting with non-pharmacological measures, and moving to pharmacological interventions in a step-wise approach.