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Conjoined twins

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Conjoined twins
Classifications and external resources
ICD-10 Q89.4
ICD-9 759.4
A painting of Chang and Eng Bunker, circa 1836

Conjoined twins are twins whose bodies are joined together at birth. This happens where the zygote of identical twins fails to completely separate. Conjoined twins occur in an estimated one in 200,000 births, with approximately half being stillborn. The overall survival rate for conjoined twins is between 5% and 25%. Conjoined twins are more likely to be female (70-75%).

Perhaps the most famous pair of conjoined twins were Chang and Eng Bunker (18111874), Chinese brothers born in Siam, now Thailand. They traveled with P.T. Barnum's circus for many years and were billed as the Siamese Twins; due to their notoriety and the rarity of the condition, today the term is frequently used as a synonym for conjoined twins. Chang and Eng were joined by a band of cartilage at the chest (xiphopagus). In modern times, they could have been separated easily.

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[edit] Types of conjoined twins

There are several different types of conjoined twin:

  • Thoracopagus: Bodies fused in the thorax. The heart is always involved in these cases; when the heart is shared, prospects for a long life, either with or without separation surgery, are poor (35-40% of cases).
  • Omphalopagus: Joined at the lower chest. The heart is not involved in these cases but the twins often share a liver, digestive system, diaphragm and other organs (34% of cases).
  • Pygopagus (iliopagus): Joined, usually back to back, to the buttocks (19% of conjoined twins).
  • Cephalopagus: Heads fused, bodies separated. These twins generally cannot survive due to severe malformations of the brain. Also known as janiceps (after the two-faced god Janus) or syncephalus.
    • Cephalothoracopagus: Bodies fused in the head and thorax. These twins also generally cannot survive. (Also known as epholothoracopagus or craniothoracopagus.)
  • Craniopagus: Skulls fused, but bodies separate (2%).
  • Dicephalus: Two heads, one body with two legs and two, three, or four arms (dibrachius, tribrachius or tetrabrachius, respectively.) Abigail and Brittany Hensel, 16-year-old conjoined twins from the United States, are of the dicephalus tribrachius type, with their third arm having been removed while they were very young.
  • Ischiopagus: Anterior union of the lower half of the body, with spines conjoined at a 180° angle (6% of cases). Or with the spines separate but both the pelvises forming a single big ring which includes two sacrums and two pubic symphyses.
  • Ischio-omphalopagus: The most well known type of conjoined twins. The Twins are conjoined with spines in a Y-shape. They have four arms and usually two or three legs. These cases can be challenging because the twins often share reproductive and excretory systems.
  • Parapagus: lateral union of the lower half extending variable distances upward, with the heart sometimes involved (5% of cases).
  • Diprosopus: One head, with two faces side by side.

In some cases, parts of the brain have been known to be shared between conjoined twins joined at the head.

Occasionally one of the twins will fail to develop properly, effectively acting as a parasite upon the normally developed twin: this condition is known as parasitic twinning or asymmetric conjoined twins. One twin may absorb the other, which is known as inclusion twinning.

Natural death of the twins can occur within hours or a few days.

[edit] Conjoined twins in history

Image:Nuremberg chronicles - Male Siamese twins (CCXVIIr).jpg The earliest known case of conjoined twins dates from the year 945, when a pair of conjoined twin brothers from Armenia were brought to Constantinople for medical evaluation. The English twin sisters Mary and Eliza Chulkhurst, who were conjoined at the back (pygopagus), lived from 1100 to 1134 and were perhaps the best-known early example of conjoined twins. Other early conjoined twins to attain notoriety were the "Scottish brothers", allegedly twins of the dicephalus type, essentially two heads sharing the same body (14601488, although the dates vary); the pygopagus Helen and Judith of Szony, Hungary (17011723), who enjoyed a brief career in music before being sent to live in a convent; and Rita and Cristina Parodi of Sardinia, born in 1829. Rita and Cristina were dicephalus tetrabrachius (one body with four arms) twins and although they died at only eight months of age, they gained much attention as a curiosity when their parents exhibited them in Paris.

Several sets of conjoined twins lived during the nineteenth century and made careers for themselves in the performing arts, though none achieved quite the same level of fame and fortune as Chang and Eng. Most notably, Millie and Christine McCoy (or McKoy), pygopagus twins, were born into slavery in North Carolina in 1851. They were sold to a showman, J.P. Smith, at birth, but were soon kidnapped by a rival showman. The kidnapper fled to England but was thwarted when England banned slavery. Smith traveled to England to collect the girls and brought with him their mother, Monimia, from whom they had been separated. He and his wife provided the twins with an education and taught them to speak five languages, play music, and sing. For the rest of the century the twins enjoyed a successful career as "The Two-Headed Nightingale" and appeared with the Barnum Circus. In 1912 they died of tuberculosis, 17 hours apart.

Giovanni and Giacomo Tocci, from Locana, Italy, were immortalized in Mark Twain's short story "Those Extraordinary Twins" as fictitious twins Angelo and Luigi. The Toccis, born in 1877, were dicephalus tetrabrachius twins, having one body with two legs, two heads, and four arms. From birth they were forced by their parents to perform and never learned to walk, as each twin controlled one leg (in modern times physical therapy allows twins like the Toccis to learn to walk on their own). They are said to have disliked show business. In 1886, after touring the United States, the twins returned to Europe with their family, where they fell very ill. They are believed to have died around this time, though some sources claim they survived until 1940, living in seclusion in Italy.

Conjoined twins who appeared in the public eye during the 20th and 21st centuries include:

[edit] Criticism of the term

As elaborated upon by the Rotten Library, the use of "conjoined" to describe said condition is in dispute:

..Unfortunately, the term is completely inaccurate, since "conjoined" means "to join or become joined together, or to unite," which is exactly the opposite of what happens in these cases. Siamese twins can't be "conjoined" because they were never separated in the first place, which leaves us in a semantic quandary that can only be resolved by a swift and totally arbitrary ruling... [1]

[edit] See also

[edit] External links

de:Siamesischer Zwilling es:Siameses fr:Frères siamois ko:결합 쌍둥이 id:Kembar siam it:Gemelli siamesi he:תאומים סיאמיים nl:Siamese tweeling pl:Zroślak fi:Siamilaiset kaksoset sv:Siamesiska tvillingar zh:連體嬰

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