Monday, July 17, 2006

hiatal hernia : Individual hernias

Disc herniation
In this condition, the central weak part of the intervertebral disc (nucleus pulposus, which helps absorb shocks to our spine) herniates through the fibrous band (annulus fibrosus) by which it is normally bound. This usually occurs low in the back at the lumbar level (=lumbar disc hernia), and can cause back pain which may radiate downwards. When the sciatic nerve is involved, this may cause sciatic pain.

Inguinal hernia
Diagram of an indirect, scrotal inguinal hernia ( median view from the left).By far the most common hernias (up to 75% of all abdominal hernias) are the so-called inguinal hernias. For a thorough understanding of inguinal hernias, much insight is needed in the anatomy of the inguinal canal. Inguinal hernias are further divided into the more common indirect inguinal hernia (2/3, depicted here), in which the inguinal canal is entered via a congenital weakness at its entrance (the internal inguinal ring), and the "direct" type (1/3), where the hernia contents push through a weak spot in the back wall of the inguinal canal. Inguinal hernias are more common in men than women while femoral hernias are more common in women.


Femoral hernia
Femoral hernias occur just below the inguinal ligament, when abdominal contents pass into the weak area at the posterior wall of the femoral canal. They can be hard to distinguish from the inguinal type (especially when ascending cephalad): however, they generally appear more rounded, and, in contrast to inguinal hernias, there is a strong female preponderance in femoral hernias. The incidence of strangulation in femoral hernias is high. Repair techniques are similar for femoral and inguinal hernia.


Umbilical hernia
Umbilical hernias are especially common in infants of African descent, and occur more in boys. They involve protrusion of intraabdominal contents through a weakness at the site of passage of the umbilical cord through the abdominal wall. These hernias often resolve spontaneously. Umbilical hernias in adults are largely acquired, and are more frequent in obese or pregnant women. Abnormal decussation of fibers at the linea alba may contribute.

Incisional hernia
An incisional hernia occurs when the defect is the result of an incompletely healed surgical wound. When these occur in median laparotomy incisions in the linea alba, they are termed ventral hernias. These can be the most frustrating and difficult to treat, as the repair utilizes already attenuated tissue.

Diaphragmatic hernia
Diagram of a hiatus hernia (coronal section, viewed from the front).Higher in the abdomen, an (internal) "diaphragmatic hernia" results when part of the stomach or intestine protrudes into the chest cavity through a defect in the diaphragm.

A hiatus hernia is a particular variant of this type, in which the normal passageway through which the esophagus meets the stomach (esophageal hiatus) serves as a functional "defect", allowing part of the stomach to (periodically) "herniate" into the chest. Hiatus hernias may be either "sliding," in which the gastroesophageal junction itself slides through the defect into the chest, or non-sliding (also known as para-esophageal), in which case the junction remains fixed while another portion of the stomach moves up through the defect. Non-sliding or para-esophageal hernias can be dangerous as they may allow the stomach to rotate and obstruct. Repair is usually advised.

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