A hernia is a bulge or protrusion of an organ or part of an organ through the structure or muscle that normally contains it. There are many different types of hernias. All are named according to the part that protrudes or by the area through which the protrusion occurs. Such areas include the brain, abdomen, groin, spine, and chest.
The most familiar types of hernias are those in which part of the intestines protrude through the abdominal wall. According to the National Center for Health Statistics, about five million people in the United States are afflicted with an abdominal hernia at any one time. An inguinal hernia appears as a bulge in the groin. It can occur with or without pain. Inguinal hernias account for 80% of all hernias and are more common in men, in whom they may descend
Hernias can be either congenital or acquired. Congenital means that the individual was born with an abnormal opening, allowing the hernia to occur. Such a hernia may show up immediately after birth, may cause no symptoms for years to come, or may never result in symptomatology. An acquired hernia is one that was not present at birth, but that occurred later, either due to some other anatomical abnormality, or due to weakening of an area with use and aging.
Hernias that involve loops of intestine, or other abdominal contents, may be reducible, meaning that the individual can push on the bulging area with a hand to move the intestine back into the abdomen. When a hernia cannot be reduced, it is said to be incarcerated. The greatest risk with any hernia containing intestine is strangulation, in which the hernia is incarcerated, and blood supply to the intestine is cut off. This is a medical emergency, and without surgical intervention, an area of the intestine may well die off.
Most people, when they hear or use the word hernia, are referring to an inguinal hernia (the inguinal area, also called the groin, is that area where the thigh and the abdomen meet), in which a loop of the intestine has passed through a weak muscular area. There are three main types of groin hernias: direct inguinal, indirect inguinal, and femoral. These are classified according to the anatomical route that the hernia takes. In men, a herniated loop of intestine may enter the scrotum. This is the type of hernia that the physician is testing for when giving the dreaded command: “Cough!” Pregnancy, obesity, heavy lifting, and medical conditions that increase the pressure within the abdomen (emphysema or other lung conditions causing frequent coughing; constipation; swelling of prostate causing difficulty urinating) can all predispose to hernia, or worsen an already existing hernia. Most physicians favor surgical repair of groin hernia, even those which are reducible, to avoid future incarceration and strangulation, which can lead to dangerous complications.
Abdominal hernias include umbilical hernias, hernias through the scar left by a previous surgical incision, and hernias through the muscles of the abdominal wall. All of these types of hernias involve abdominal contents (often a loop of intestine) that pop through a weakened area. Some umbilical hernias are present at birth, particularly in premature infants, and are due to incomplete closure of an area called the umbilical ring, which should close before birth. Most of these umbilical hernias do not require surgery, because the ring usually decreases in size and then closes on its own within the first two to four years of life.
A hiatal hernia occurs when a portion of the stomach protrudes above the diaphragm (the diaphragm is the large, sheet-like muscle which should separate the contents of the chest from the contents of the abdomen). The majority of hiatal hernias (90%) are of a type causing reflux, which occurs when the acidic contents of the stomach wash up the esophagus (the esophagus is the tube that should only carry swallowed substances down into the stomach). Presence of these acidic contents burn the esophagus, resulting in the symptom commonly referred to as heartburn. Most of these types of hernias do not require surgical repair. Symptoms are helped by various medications that decrease the acidity of the stomach contents, and thwarting the effects of gravity that can exacerbate the problem at night (patients should go to sleep propped up on an angle by a sufficient number of pillows). This other type of hiatal hernia more frequently requires surgical repair, because its complications include hemorrhage (massive bleeding), incarceration, and strangulation (which can result in death of stomach tissue). Furthermore, in this more serious type of hiatal hernia, other abdominal contents (intestine, spleen) may also protrude into the chest cavity, and pressure from crowding in the chest cavity can result in heart problems.
Diaphragmatic hernias can be congenital, or acquired through trauma (for example, a knifing). Congenital diaphragmatic hernias occur during development before birth, when the tissues making up the diaphragm do not properly close off the area between the abdomen and chest cavities. These abnormal contents, especially the intestine and spleen, push into the chest cavity, applying pressure to the heart, and sometimes preventing adequate development of the lungs. A baby born with such a defect usually experiences extreme respiratory distress, and requires immediate surgery.
Herniation of brain tissue can occur when an expanding mass (tumor) begins to take up space within the finite area of the skull (for example, if there is high pressure in the skull from fluid accumulation, and a test called a spinal tap, or lumbar puncture, is performed). Displacement of brain tissue in this way results in compression of various areas of the brain, and greatly compromised vital functions (vital functions are those brain-directed functions necessary for the basics of human life, for example, breathing and heart rate). Herniation of brain tissue usually results either in death, or in massive and permanent brain damage.
The spine is made up of individual bones, the vertebrae, separated from each other by a disc to provide insulation and cushioning. Disc herniation, or a slipped disc, occurs when the interior area of the disc breaks through the outer area of the disc, and pushes into the spinal canal, or when the entire disc
Congenital —A condition or disability present at birth.
Diaphragm —The sheet-like muscle that is supposed to separate the contents of the abdomen from the contents of the chest cavity. The diaphragm is a major muscle involved in breathing.
Incarcerated —Refers to a hernia that gets trapped protruding through an abnormal opening. Most frequently refers to loops of the intestine that cannot be easily replaced in their normal location.
Inguinal —Referring to the groin area, that area where the upper thigh meets the lower abdomen.
Invertebral disc —The cartilaginous disc located between each of the vertebral bones of the spine. This disc provides cushioning and insulation.
Reduce —The ability to put a displaced part of the anatomy (in particular, the loops of intestine present in a hernia) back in their correct location by simply pushing on the bulging area.
Strangulation —A situation that occurs when the blood supply to an organ is cut off, resulting in death of that tissue.
becomes displaced from its normal positioning. Disc herniation occurs most commonly in the neck area, and in the lower back, and can be a result of wear-and-tear from aging or from trauma.
Problems due to disc herniation occur because the displaced disc presses on the spinal cord or the nerves leaving the spinal cord. This activity can result in problems ranging from tingling in the hands, feet, or buttocks; weakness of a limb; back, leg, or arm pain; loss of bladder control; loss of normal reflexes (for example, normally tapping the knee with an examination hammer results in an involuntary kicking out the foot; disc herniation may make it impossible to elicit this foot kick, as well as other reflexes); or in very extreme cases, paralysis.
Cases of disc herniation with less extreme symptomatology can be treated with such measures as a neck brace or back brace, medications to reduce swelling (nerve roots experiencing pressure from the protruding disc may swell, further compromising their function), heat, and pain medications. When pain is untreatable, or loss of function is severe or progressive, surgery may be required to relieve or halt further progression of the symptoms.
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Longmore, J. Murray. Oxford Handbook of Clinical Medicine. Oxford, UK: Oxford University Press, 2004.
The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck, 2006.