Hernia

Hernia
Specialty	General surgery

A hernia is a protrusion of a tissue, structure, or part of an organ through the muscular tissue or the membrane by which it is normally contained (definition from MeSH). The hernia has 3 parts: the orifice through which it herniates, the hernial sac, and its contents. Since used alone "hernia" almost always refers to the passage of abdominal contents through their usual boundaries, these will be emphasised in this article; non-visceral hernias will be addressed at the end.

A hernia is often likened to the failure of a tire. Here a split in the sidewall of an excavator tire allows the inner tube to protrude.

A hernia may be likened to a failure in the sidewall of a pneumatic tire. The tire's inner tube behaves like the organ and the sidewall like the body cavity wall providing the restraint. A weakness in the sidewall allows a bulge to develop, which can become a split, allowing the inner tube to protrude, and leading to the eventual failure of the tire.

Pathophysiology

By far most 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 intervertebral disc, and causes back pain or sciatica.

Hernias may present either with pain at the site, a visible or palpable lump, or in some cases by 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 by or accompanied by an organ.

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.

Hernias are generally not caused by trauma.

Epidemiology

Between 1995 and 2005, 16,742 Americans died from a hernia.

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
• hernias of the nucleus pulposus of the intervertebral discs
• intracranial hernias

Each of the above hernias may be characterised 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 resistentiae (Lat. place of least resistance) that is congenital, but only becomes symptomatic later on 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 herniate into the chest, or completely.
• 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 produces 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.
• reducible or irreducible (also known as incarcerated): the hernial contents can or 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. These signs mandate urgent surgery.
• another complication arises when the herniated organ itself, or surrounding organs start dysfunctioning (for example, sliding hernia of the stomach causing heartburn, lumbar disc hernia causing sciatic nerve pain, etc.)

Treatment

It is generally advisable to repair hernias in a timely fashion, in order to prevent complications such as organ dysfunction, gangrene, and multiple organ dysfunction syndrome. Most abdominal hernias can be surgically repaired, and recovery rarely requires long-term changes in lifestyle. Uncomplicated hernias are principally repaired by pushing back, or "reducing", the herniated tissue, and then mending the weakness in muscle tissue (an operation called herniorraphy). If complications have occurred, the surgeon will check the viability of the herniated organ, and resect it if necessary. Modern muscle reinforcement techniques involve synthetic materials (a mesh prosthesis) that avoid over-stretching of already weakened tissue (as in older, but still useful methods). The mesh is placed over the defect, and sometimes staples are used to keep the mesh in place. Increasingly, some repairs are performed through laparoscopes.

Many patients are managed through surgical daycare centers, and are able to return to work within a week or two, while heavy activities are prohibited for a longer period. Surgical complications have been estimated to be up to 10%, but most of them can be easily addressed. They include surgical site infections, nerve and blood vessel injuries, injury to nearby organs, and hernia recurrence.

Generally, the use of external devices to maintain reduction of the hernia without repairing the underlying defect (such as hernia trusses, trunks, belts, etc.), is not advised. Exceptions are uncomplicated incisional hernias that arise shortly after the operation (should only be operated after a few months), or inoperable patients.

It is essential that the hernia not be further irritated by carrying out strenuous labour.

Individual hernias

A sportman's hernia is a syndrome characterized by chronic groin pain in athletes and a dilated superficial ring of the inguinal canal, although a true hernia is not present.

Inguinal hernia

Main article: 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 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 more common in men than women while femoral hernias are more common in women.

Femoral hernia

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 hernia

Main article: 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

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 hernia

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.

Frontal chest X-ray showing a hernia of Morgagni.

A congenital diaphragmatic hernia is a distinct problem, occurring in up to 1 in every 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 types of hernia

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:

• Brain hernia: herniation of part of the brain because of excessive intracranial pressure. This may be a life-threatening condition, especially if the brain stem (responsible for some important vital signs) is involved.
• 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 immediately beneath the skin.
• epigastric hernia: hernia through the linea alba above the umbilicus.
• Littre's hernia: hernia involving a Meckel's diverticulum
• lumbar hernia: hernia in the lumbar region (not to be confused with a lumbar disc hernia), contains following entities:
  • Petit's hernia - hernia through Petit's triangle (inferior lumbar triangle)
  • Grynfeltt's hernia - hernia through Grynfeltt-Lesshaft triangle (superior lumbar triangle)
• obturator hernia: hernia through obturator canal
• pantaloon hernia: a combined direct and indirect hernia, when the hernial sac protrudes on either side of the inferior epigastric vessels
• 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: strangulated hernia involving only one sidewall of the bowel, which can result in bowel perforation through ischaemia without causing bowel obstruction or any of its warning signs.
• 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
• Spinal disc herniation, or "herniated nucleus pulposus"

Main article: spinal disc herniation.

A spinal disc herniation is a condition where 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 or lumbo-sacral level and can cause back pain which usually radiates well into the thigh or leg. When the sciatic nerve is involved, the symptom complex is called sciatica. Herniation can occur in the cervical vertebrae too. A nucleoplasty is an operation to repair the herniation.

Hernias in pop culture

• "Weird Al" Yankovic recorded a song entitled "Living With A Hernia", on his Polka Party! album. The song is a parody of James Brown's "Living In America", and describes the discomfort associated with suffering a hernia, as well as listing common types of hernias.

• Comedian Bill Engvall has a routine "My hernia".

• When Robin Williams appeared on Inside the Actors Studio in 2002, a man in the audience acquired a hernia from laughing so hard. The man had to be removed from the studio in an ambulance.

• In a television advertisement for Boost Mobile, blink-182 drummer Travis Barker appeared in a story of what would have happened if Barker did not have Boost Mobile. He becomes a professional bodybuilder and suffers a "compound hernia" (possibly a counterpart to a compound fracture). The word "compound" was removed from this commercial's voiceover within weeks of its first airing.

• In a Bill Cosby show (Fat Albert's got a hernia), he describes developing a hernia from picking up a sewer lid, and what happened to him afterwards.

• On an episode of Friends, Joey got a hernia due to weightlifting, but had to wait to have it treated because his insurance lapsed. He eventually paid for the surgery by very realistically playing the part of 'Dying Man' in a movie.

• On an episode of M*A*S*H, Major Burns hernia becomes strangulated during a surgery session.

• On an episode of The Venture Brothers, Dr.Venture thinks he has a hernia, but it is really his unborn brother, Jonas Venture Junior.

References

• Surgical recall, 2nd edition, by Lorne. H. Blackbourne, published by Lippincott Williams & Wilkins
• Sabiston textbook of surgery, 17th edition, Townsend et.al.(e.d.), Elsevier-Saunders