The word inflammation comes from the Latin word inflammare, which means “to set on fire.” In the 1st century, the Roman medical writer Aulus Cornelius Celsus is credited with first documenting the four cardinal signs of inflammation: calor, dolor, rubor, and tumor.

These four words mean, respectively, “heat,” “pain,” “redness,” and “swelling.” The symptoms make up what’s considered the classic inflammatory response that may occur a few minutes or hours after an injury, such as a muscle tear, or during an infection. Today, we know that inflammation is the body’s way of protecting us: White blood cells release chemicals to ward off foreign substances and increase the flow of blood to the area, causing redness and warmth. Some of the chemicals cause fluid to leak into the tissues, resulting in swelling, and nerves are stimulated in the process, causing pain. In the case of a muscle strain or sprain, the patient can lessen inflammation by applying ice or elevating the affected limb above the heart to keep blood from rushing to the area.

Celsus’s description of inflammation emphasized the importance of clinical observation, rather than philosophy-based medicine. A century later, the Greek physician Galen (AD 129–216) elaborated on the theory of inflammation, suggesting that inflammation and pus were necessary parts of the healing process. In 1871, the German pathologist Rudolf Virchow (1821–1902) added a fifth sign of inflammation: functio laesa, or “loss of function” (although some sources attribute this addition to Galen as well). Virchow was also the first to make a connection between inflammation and cancer, writing that inflammation was a predisposing factor to the formation of tumors.

ADDITIONAL FACTS

  1. The five signs generally appear when acute inflammation occurs on the surface of the body, while internal inflammation usually does not cause all five symptoms. Pneumonia, or inflammation of the lungs, for example, typically does not cause pain.
  2. Inflammation—especially in the case of an infection—may also be associated with flulike symptoms such as fever, chills, headache, and muscle stiffness.
  3. In his writings, Celsus also described many 1st-century Roman surgical procedures, including the removal of a cataract, treatment for bladder stones, and the setting of fractures.