Friday, November 15, 2013

What is necrosis?


Causes and Symptoms

“Necrosis” refers to the degeneration of cells or tissues after cell death occurs for any reason, generally in localized regions of the body. Thus, necrosis is tissue degeneration, which occurs secondary to cell death from any cause. Necrosis is most commonly the result of ischemia, traumatic injury, bacterial infection, or toxins (including excessive steroids or alcohol).



In its earliest stage, there are often no symptoms of necrosis. Tissue damage begins to occur within twelve hours of cell death. When symptoms do begin to occur, they range from atrophy to decreased range of motion and pain to the development of gangrenous tissue.




Treatment and Therapy

The damage done to the tissue resulting from cell death is permanent. Any treatment of necrosis is aimed at minimizing further cell death and tissue injury. In the case of heart
disease, treatment of the underlying condition to alleviate hypoxia prevents further cell death from ischemia. In the case of bacterial infection, antibiotics are used to treat the infection and prevent cell death and tissue damage. In the case of necrosis of bone tissue from decreased blood supply, the aim of treatment is to minimize further bone loss. This type of necrosis, known as “avascular necrosis” or “osteonecrosis,” is treated with nonsteroidal anti-inflammatory drugs (NSAIDs) to relieve pain, exercise to improve range of motion, electrical treatment to stimulate bone growth, or surgery to reshape or graft bone or to replace joints.




Perspective and Prospects

The term “necrosis” was used nearly two thousand years ago in ancient Greek textbooks to refer to changes within tissue, long after cell death had occurred, that were visible to the naked eye. With the advent of light microscopy, the tissue damage following cell death became visible within twelve to twenty-four hours.


In 1859, Rudolf Virchow, in his renowned text Cellular Pathology as Based upon Physiological and Pathological Histology, discussed degeneration, necrosis, mortification, and gangrene, using these terms more or less synonymously. It should be noted that he used the term “necrosis” to refer to an advanced stage of tissue breakdown. At this point, the breakdown had to be visible to the naked eye, since light microscopy had not yet been developed. Today, using the microscope, tissue damage resulting from cell death is obvious and often identical whether caused by ischemia, traumatic injury, bacteria, or toxins.




Bibliography


A.D.A.M. Medical Encyclopedia. . "Necrosis." MedlinePlus, March 23, 2013.



"Cell Death." In Pathology: Clinicopathologic Foundations of Medicine, edited by Raphael Rubin, David Sheldon Strayer, and Emanuel Rubin. 6th ed. Baltimore: Lippincott, 2012.



Majno, G., and I. Joris. “Apoptosis, Oncosis, and Necrosis: An Overview of Cell Death.” American Journal of Pathology 146, no. 1 (1995): 3–15.



"Necrosis." In Taber's Cyclopedic Medical Dictionary, edited by Donald Venes. 21st ed. Philadelphia: F. A. Davis, 2010.



Parker, J. N., and P. M. Parker. The Official Patient’s Sourcebook on Avascular Necrosis. San Diego, Calif.: Icon Health, 2002.

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