A cardinal sign is a major symptom that doctors utilize to make a diagnosis. In the case of inflammation, there are five cardinal signs that characterize the condition: pain, heat, redness, swelling, and loss of function.
Inflammation is a biological process that your body uses to help protect you. It is important to note, however, that not all five cardinal signs are present in every instance of inflammation. Moreover, the inflammatory process could be silent and not cause noticeable symptoms.
What is Inflammation?
Inflammation is a process that protects the body from infection and foreign substances, such as bacteria and viruses. Inflammation helps the body by producing white blood cells and other substances.
When the inflammation process starts, chemicals in the white blood cells are released into the blood and the affected tissues to protect the body. The chemicals increase blood flow to the infected or injured body areas, causing redness and warmth in those locations.
These chemicals may also cause leaking of fluids into tissues, resulting in swelling. This protective process will also stimulate nerves and tissues, causing pain.
Inflammation is classified as either acute or chronic. Acute inflammation is short-term, while chronic inflammation is long-lasting and even destructive.
Acute inflammation may include heat of a fever or warmth in the affected area. Acute inflammation is a healthy and necessary function that helps the body to attack bacteria and other foreign substances anywhere in the body. Once the body has healed, inflammation subsides. Examples of conditions that cause acute inflammation include:
- an infected ingrown toenail.
- a sore throat related to the flu.
- skin cuts and scratches.
- dermatitis, which describes multiple skin conditions including eczema, which causes red, itchy inflamed rashes in areas where the skin flexes (such as inside the elbows and behind the knees).
- sinusitis, which can cause short-term inflammation in the membranes of the nose and surrounding sinuses (usually the result of a viral infection)
Chronic inflammation, on the other hand, may continue to attack healthy areas if it doesn't turn off. It can occur anywhere in the body and may trigger any number of chronic diseases, depending on the area of the body affected.
Examples of conditions that cause chronic inflammation include:
- inflammatory arthritis, which covers a group of conditions distinguished by inflammation of joints and tissues (including rheumatoid arthritis, lupus, and psoriatic arthritis).
- asthma, which causes inflammation of the air passages that carry oxygen to the lungs. Inflammation causes these airways to become narrow and breathing to become difficult.
- inflammatory bowel disease (IBD). IBD refers to Crohn’s disease and ulcerative colitis. Both these conditions cause chronic inflammation in the gastrointestinal (GI) tract that eventually causes damage to the GI tract.
Doctors and researchers sometimes refer to the five cardinal signs of inflammation by their Latin names:
- dolor (pain).
- calor (heat).
- rubor (redness).
- tumor (swelling).
- functio laesa (loss of function).
Inflammation can cause pain in joints and muscles. When inflammation is chronic, a person will experience high levels of pain sensitivity and stiffness. The inflamed areas may be sensitive to touch.
With both acute and chronic inflammation, pain is the result of inflammatory chemicals that stimulate nerve endings, causing the affected areas to feel more sensitive.
When inflamed areas of the body feel warm, it is because there is more blood flow in those areas. People with arthritic conditions may have inflamed joints that feel warm to the touch. The skin around those joints, however, may not have the same warmth. Whole-body inflammation may cause fevers as a result of the inflammatory response when someone has an illness or infection.
Inflamed areas of the body may appear red in color. This is because blood vessels of inflamed areas are filled with more blood than usual.
Swelling is common when a part of the body is inflamed. It is the result of fluid accumulating in tissues either throughout the body or in the specific affected area. Swelling can occur without inflammation, especially with injuries.
5. Loss of Function
Inflammation may cause loss of function, related to both injury and illness. For example, an inflamed joint cannot be moved properly, or it can make it difficult to breathe due to a respiratory infection.