herniation

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/01/28 00:30:16」(JST)

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Hernia
Classification and external resources
X-ray of colonic herniation
ICD-10	K40-K46
ICD-9	550-553
MedlinePlus	000960
eMedicine	emerg/251 ped/2559
MeSH	D006547

A hernia is the protrusion of an organ or the fascia of an organ through the wall of the cavity that normally contains it. There are different kinds of hernia, each requiring a specific management or treatment.

Signs and symptoms

By far the most common hernias develop in the abdomen, when a weakness in the abdominal wall evolves into a localized hole, or "defect", through which adipose tissue, or abdominal organs covered with peritoneum, may protrude. Another common hernia involves the spinal discs and causes sciatica. A hiatal hernia occurs when the stomach protrudes into the mediastinum through the esophageal opening in the diaphragm.

Hernias may or may not present with either pain at the site, a visible or palpable lump, or in some cases more vague symptoms resulting from pressure on an organ which has become "stuck" in the hernia, sometimes leading to organ dysfunction. Fatty tissue usually enters a hernia first, but it may be followed or accompanied by an organ.

Symptoms may or may not be present in some inguinal hernias, while in some other hernias they are. Symptoms and signs vary depending on the type of hernia. In the case of reducible hernias, a bulge in the groin or in another abdominal area can often be seen and felt. When standing, such a bulge becomes more obvious. Besides the bulge, other symptoms include pain in the groin that may also include a heavy or dragging sensation, and in men, there is sometimes pain and swelling in the scrotum around the testicular area.

Irreducible abdominal hernias or incarcerated hernias may be painful, but their most relevant symptom is that they cannot return to the abdominal cavity when pushed in. They may be chronic, although painless, and can lead to strangulation. Strangulated hernias are always painful and pain is followed by tenderness. Nausea, vomiting, or fever may occur in these cases due to bowel obstruction. Also, the hernia bulge in this case may turn red, purple or dark and pink.

In the diagnosis of abdominal hernias, imaging is the principal means of detecting internal diaphragmatic and other nonpalpable or unsuspected hernias. Multidetector CT (MDCT) can show with precision the anatomic site of the hernia sac, the contents of the sac, and any complications. MDCT also offers clear detail of the abdominal wall allowing wall hernias to be identified accurately.

Causes

Most of the time, hernias develop when pressure in the compartment of the residing organ is increased, and the boundary is weak or weakened.

• Weakening of containing membranes or muscles is usually congenital (which explains part of the tendency of hernias to run in families), and increases with age (for example, degeneration of the annulus fibrosus of the intervertebral disc), but it may be on the basis of other illnesses, such as Ehlers-Danlos syndrome or Marfan syndrome, stretching of muscles during pregnancy, losing weight in obese people, etc., or because of scars from previous surgery.
• Many conditions chronically increase intra-abdominal pressure, (pregnancy, ascites, COPD, dyschezia, benign prostatic hypertrophy) and hence abdominal hernias are very frequent. Increased intracranial pressure can cause parts of the brain to herniate through narrowed portions of the cranial cavity or through the foramen magnum. Increased pressure on the intervertebral discs, as produced by heavy lifting or lifting with improper technique, increases the risk of herniation.

Causes of hiatal hernia vary depending on each individual. Among the multiple causes, however, are the mechanical causes which include: poison, improper heavy weight lifting, hard coughing bouts, sharp blows to the abdomen, tight clothing and incorrect posture.

Furthermore, conditions that increase the pressure of the abdominal cavity may also cause hernias or worsen the existing ones. Some examples would be: obesity, straining during a bowel movement or urination, chronic lung disease, and also, fluid in the abdominal cavity.

Also, if muscles are weakened due to poor nutrition, smoking, and overexertion, hernias are more likely to occur.

The physiological school of thought contends that in the case of inguinal hernia, the above mentioned are only an anatomical symptom of the underlying physiological cause. They contend that the risk of hernia is due to a physiological difference between patients who suffer hernia and those who do not, namely the presence of aponeurotic extensions from the transversus abdominis aponeurotic arch.

Diagnosis

Inguinal

Main article: inguinal hernia

An incarcerated inguinal hernia as seen on CT

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. 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 inguinal hernia type (1/3), where the hernia contents push through a weak spot in the back wall of the inguinal canal. Inguinal hernias are the most common type of hernia in both men and women. In some selected cases, they may require surgery.

Femoral

Main article: 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

Main article: umbilical hernia

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

Main article: 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

Main article: 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.

A congenital diaphragmatic hernia is a distinct problem, occurring in up to 1 in 2000 births, and requiring pediatric surgery. Intestinal organs may herniate through several parts of the diaphragm, posterolateral (in Bochdalek's triangle, resulting in Bochdalek's hernia), or anteromedial-retrosternal (in the cleft of Larrey/Morgagni's foramen, resulting in Morgagni-Larrey hernia, or Morgagni's hernia).

Other hernias

Since many organs or parts of organs can herniate through many orifices, it is very difficult to give an exhaustive list of hernias, with all synonyms and eponyms. The above article deals mostly with "visceral hernias", where the herniating tissue arises within the abdominal cavity. Other hernia types and unusual types of visceral hernias are listed below, in alphabetical order:

• Amyand's hernia: containing the appendix vermiformis within the hernia sac
• Busse's Hernia: a testicle within the hernia sac
• Cooper's hernia: a femoral hernia with two sacs, the first being in the femoral canal, and the second passing through a defect in the superficial fascia and appearing almost immediately beneath the skin.
• Epigastric hernia: a hernia through the linea alba above the umbilicus.
• Hiatal hernia: a hernia due to "short oesophagus" — insufficient elongation — stomach is displaced into the thorax
• Littre's hernia: a hernia involving a Meckel's diverticulum. It is named after the French anatomist Alexis Littré (1658–1726).
• Lumbar hernia (Bleichner's Hernia): a hernia in the lumbar region (not to be confused with a lumbar disc hernia), contains the following entities:
  • Petit's hernia: a hernia through Petit's triangle (inferior lumbar triangle). It is named after French surgeon Jean Louis Petit (1674–1750).
  • Grynfeltt's hernia: a hernia through Grynfeltt-Lesshaft triangle (superior lumbar triangle). It is named after physician Joseph Grynfeltt (1840–1913).
• Maydl's hernia: two adjacent loops of small intestine are within a hernial sac with a tight neck. The intervening portion of bowel within the abdomen is deprived of its blood supply and eventually becomes necrotic.
• Morgagni hernia: a type of hernia where abdominal contents pass into the thorax through a weakness in the diaphragm
• Obturator hernia: hernia through obturator canal
• Pantaloon hernia (Saddle Bag hernia): a combined direct and indirect hernia, when the hernial sac protrudes on either side of the inferior epigastric vessels
• Paraesophageal hernia
• Paraumbilical hernia: a type of umbilical hernia occurring in adults
• Perineal hernia: a perineal hernia protrudes through the muscles and fascia of the perineal floor. It may be primary but usually is acquired following perineal prostatectomy, abdominoperineal resection of the rectum, or pelvic exenteration.
• Properitoneal hernia: rare hernia located directly above the peritoneum, for example, when part of an inguinal hernia projects from the deep inguinal ring to the preperitoneal space.
• Richter's hernia: a hernia involving only one sidewall of the bowel, which can result in bowel strangulation leading to perforation through ischaemia without causing bowel obstruction or any of its warning signs. It is named after German surgeon August Gottlieb Richter (1742–1812).
• Sliding hernia: occurs when an organ drags along part of the peritoneum, or, in other words, the organ is part of the hernia sac. The colon and the urinary bladder are often involved. The term also frequently refers to sliding hernias of the stomach.
• Sciatic hernia: this hernia in the greater sciatic foramen most commonly presents as an uncomfortable mass in the gluteal area. Bowel obstruction may also occur. This type of hernia is only a rare cause of sciatic neuralgia.
• Spigelian hernia, also known as spontaneous lateral ventral hernia
• Sports hernia: a hernia characterized by chronic groin pain in athletes and a dilated superficial inguinal ring.
• Velpeau hernia: a hernia in the groin in front of the femoral blood vessels

Characteristics

Hernias can be classified according to their anatomical location:

Examples include:

• abdominal hernias
• diaphragmatic hernias and hiatal hernias (for example, paraesophageal hernia of the stomach)
• pelvic hernias, for example, obturator hernia
• anal hernias
• hernias of the nucleus pulposus of the intervertebral discs
• intracranial hernias
• Spigelian hernia

Each of the above hernias may be characterized by several aspects:

• congenital or acquired: congenital hernias occur prenatally or in the first year(s) of life, and are caused by a congenital defect, whereas acquired hernias develop later on in life. However, this may be on the basis of a locus minoris resistantiae (Lat. place of least resistance) that is congenital, but only becomes symptomatic later in life, when degeneration and increased stress (for example, increased abdominal pressure from coughing in COPD) provoke the hernia.
• complete or incomplete: for example, the stomach may partially or completely herniate into the chest.
• internal or external: external ones herniate to the outside world, whereas internal hernias protrude from their normal compartment to another (for example, mesenteric hernias).
• intraparietal hernia: hernia that does not reach all the way to the subcutis, but only to the musculoaponeurotic layer. An example is a Spigelian hernia. Intraparietal hernias may produce less obvious bulging, and may be less easily detected on clinical examination.
• bilateral: in this case, simultaneous repair may be considered, sometimes even with a giant prosthetic reinforcement.
• irreducible: the hernial contents cannot be returned to their normal site with simple manipulation.

If irreducible, hernias can develop several complications (hence, they can be complicated or uncomplicated):

• strangulation: pressure on the hernial contents may compromise blood supply (especially veins, with their low pressure, are sensitive, and venous congestion often results) and cause ischemia, and later necrosis and gangrene, which may become fatal.
• obstruction: for example, when a part of the bowel herniates, bowel contents can no longer pass the obstruction. This results in cramps, and later on vomiting, ileus, absence of flatus and absence of defecation.
• dysfunction: another complication arises when the herniated organ itself, or surrounding organs, start to malfunction (for example, sliding hernia of the stomach causing heartburn, lumbar disc hernia causing sciatic nerve pain, etc.).

Treatment

Main articles: Hernia repair and Inguinal hernia surgery

Hernia repair being performed aboard the amphibious assault ship USS Bataan.

For a hernia like inguinal hernia, surgery is no longer recommended in most cases. However, it is in few cases advisable to repair some other kinds of hernias, in order to prevent complications such as organ dysfunction, gangrene and multiple organ dysfunction syndrome. Most abdominal hernias can be surgically repaired, but surgery often has complications, such as chronic groin pain. Time needed for recovery after treatment is greatly reduced if hernias are operated on laparoscopically, the minimally invasive operation most commonly used today. Uncomplicated hernias are principally repaired by pushing back, or "reducing", the herniated tissue, and then mending the weakness in muscle tissue (an operation called herniorrhaphy). If complications have occurred, the surgeon will check the viability of the herniated organ, and resect it if necessary.

Muscle reinforcement techniques often involve synthetic materials (a mesh prosthesis). The mesh is placed either over the defect (anterior repair) or under the defect (posterior repair). At times staples are used to keep the mesh in place. These mesh repair methods are often called "tension free" repairs because, unlike some suture methods (e.g. Shouldice), muscle is not pulled together under tension. However, this widely used terminology is misleading, as there also exists many tension-free suture methods that do not use mesh (e.g. Desarda, Guarnieri, Lipton-Estrin...).

Evidence suggests that tension-free methods (with or without mesh) often have lower percentage of recurrences and the fastest recovery period compared to tension suture methods. However, among other possible complications, prosthetic mesh usage seems to have a higher incidence of chronic pain and, sometimes, infection.

One study attempted to identify the factors related to mesh infections and found that compromised immune systems (such as diabetes) was a factor. Mesh has also become the subject of recalls and class action lawsuits.

Laparoscopic surgery is also referred to as "minimally invasive" surgery, which requires one or more small incisions for the camera and instruments to be inserted, as opposed to traditional "open" or "microscopic" surgery, which requires an incision large enough for the surgeon's hands to be inserted into the patient. The term microscopic surgery refers to the magnifying devices used during open surgery.

Many patients are managed through day surgery centers, and are able to return to work within a week or two, while intensive activities are prohibited for a longer period. Patients who have their hernias repaired with mesh often recover in a number of days, though pain can last longer, and often forever. Surgical complications have been estimated to be more than 20 percent. They include chronic pain, surgical site infections, nerve and blood vessel injuries, injury to nearby organs, and hernia recurrence.

Due to surgical risks, mainly chronic pain risk, the use of external devices to maintain reduction of the hernia without repairing the underlying defect (such as hernia trusses, trunks, belts, etc.) are often used. In particular, we can mention uncomplicated incisional hernias that arise shortly after the operation (should only be operated after a few months), or inoperable patients. There have been known cases where hiatal and esophageal hernias have shown signs of improvements after the patient stopped producing stress on the affected area by fasting or parenteral nutrition. It is essential that the hernia not be further irritated by carrying out strenuous labour.

Complications

Complications may arise post-operation, including rejection of the mesh that is used to repair the hernia. In the event of a mesh rejection, the mesh will very likely need to be removed. Mesh rejection can be detected by obvious, sometimes localised swelling and pain around the mesh area. Continuous discharge from the scar is likely for a while after the mesh has been removed.

A surgically treated hernia can lead to complications, while an untreated hernia may be complicated by:

• Inflammation
• Irreducibility
• Obstruction of any lumen, such as bowel obstruction in intestinal hernias
• Strangulation
• Hydrocele of the hernial sac
• Haemorrhage
• Autoimmune problems
• Incarceration, which is where it cannot be reduced, or pushed back into place, at least not without very much external effort. In intestinal hernias, this also substantially increases the risk of bowel obstruction and strangulation.

References

External links

• Hernia Resources
• Hernia Information
• The Hernia Blog
• Hernia Symptoms
• Sports Hernia: Common Misdiagnosis
• Hernia:The World Journal of Hernia and Abdominal Wall Surgery

Pictures

• Hernia Types and Classifications
• Photos of Hernias

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Japanese Journal

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Related Links

• Herniation | definition of herniation by Medical dictionary

herniation [her″ne-a´shun] abnormal protrusion of an organ or other body structure through a defect or natural opening in a covering membrane, muscle, or bone. (See also hernia.) Herniation syndromes. From Ignatavicius and ...

• herniationの意味・用例｜英辞郎 on the WEB：アルク

herniation 【名】《医》ヘルニア形成 【参考】hernia - アルクがお届けする進化するオンライン英和・和英辞書データベース。一般的な単語や連語から、イディオム、専門用語、スラングまで幅広く収録。

Related Pictures

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★リンクテーブル★

拡張検索	「downward transtentorial herniation」「reversed transtentorial herniation」「lumbar disc herniation」「lumbar disk herniation」

「downward transtentorial herniation」

　　[★] 下行性テント切痕ヘルニア

「reversed transtentorial herniation」

　　[★] 逆行性テント切痕ヘルニア

「lumbar disc herniation」

　　[★]

腰椎椎間板ヘルニア

「lumbar disk herniation」

　　[★] 腰椎椎間板ヘルニア