Injuries following trauma can result in severe, acute pain to the individual. Trauma patients will often experience more than one type of pain in the days and months following a severe injury. The pain may be either short-term or chronic in nature.
Several models have been proposed over the years to help us better understand pain. Each is useful in certain situations. The most common model used by doctors, and the easiest to understand is the medical (physical or biological) model of pain. The medical model focuses totally on the physical injury (or disease) as the only source causing pain and primarily emphasizes traditional medicine techniques and pain medications to diagnose and treat pain. This model is the main method used for understanding and treating short-term pain, the type of pain that is most likely a result of acute traumatic injuries.
One of the earliest medical models, or theories, to explain pain was proposed by the French philosopher Descartes in the year 1664. He described pain as simply a biological phenomenon. Something that causes local tissue damage, such as heat, a sharp cut, or a blow to a body region causes special sensory nerves to recognize the tissue damage and send a signal directly to the brain. The brain immediately detects this signal as pain. The larger the tissue damage, the bigger the signal; and, presumably as the signal increases, the amount of pain detected by the brain will also proportionately increase. We now know that pain is not that simple. Even acute pain can be of several types, and can be perceived at very different levels of severity by different individuals. The pain caused by acute injury is generally explained by the physiology and interaction of the peripheral and the central nervous system. This is explained in greater detail below under the Physiology section.
The biopsychosocial model is another theory that may be useful in understanding and treating pain, particularly chronic pain. This model is more a philosophy, first proposed by George Engel in 1977, to help patients and doctors understand that illness and injury, and their associated symptoms, are affected by multiple levels of organization. In other words, pain is not simply a physical or biological phenomenon. Pain is closely associated with the individual's social background and psychological makeup. In chronic pain syndromes, fear of worsening the chronic pain can lead to inactivity, decreased social interactions, avoiding work, and reducing the usual recreational activities. This behavior in turn can lead to anxiety and depression, which can actually make the chronic pain more intense. The biopsychosocial model focuses on the way a person’s biology (medical condition), psychology, and social environment are all related to the pain experience. To really understand and treat chronic pain it is important to examine all three of these areas.