Conjoined twins

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**Conjoined twins**
*Classification & external resources*
ICD-10	Q 89.4
ICD-9	759.4

A painting of Chang and Eng Bunker, circa 1836

"Siamese twins" redirects here. For other senses of that term, see Siamese twins (disambiguation).

Conjoined twinss 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 (1811–1874), 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 flesh, cartilage,and their shared liver at the torso. In modern times, they could have been separated easily.

Conjoined twins form in two ways. The first is fission, in which the fertilized egg splits partially, resulting in two-to-one type conjoined twins, i.e. Dicephalus twins. The second is fusion, a more common type of conjoined twinning, is when a fertilized egg completely seperates, but stem cells (which search for similar cells) find like-stem cells on the other twin and fuses the twins together. This results in single and relative organ sharing, i.e. Thorapagus twins.

1 Conjoined twins in history
2 Types of conjoined twins
3 Separation
4 See also
5 External links

[edit] Conjoined twins in history

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Conjoined twins. From the Nuremberg Chronicle (1493).

The earliest known case of conjoined twins dates from the year ????, 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 (1460–1488, although the dates vary); the pygopagus Helen and Judith of Szony, Hungary (1701–1723), 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:

Rosa and Josepha Blazek of Bohemia (modern-day Czech Republic (1878–1922);
Lucio and Simplicio Godina of Samar, Philippines (1908–1936);
Daisy and Violet Hilton of Brighton, East Sussex, England (1908–1969);
Mary and Margaret Gibb of Holyoke, Massachusetts (1912–1967);
Yvonne and Yvette McCarther of Los Angeles, California (1949–1992);
Ladan Bijani and Laleh Bijani of Shiraz, Iran (Persia) (1974–2003);
Ronnie and Donnie Galyon of Ohio (1951–), currently the world's oldest living conjoined twins.
Lori and Reba Schappell of Reading, Pennsylvania (1961–), American entertainers;
Ganga and Jamuna Shreshta of Nepal, conjoined twins who separated in a landmark surgery in Singapore in 2001;
Krista and Tatiana Hogan born in Vancouver, British Columbia (2006–), craniopagus conjoined twins;
At Guntur, India the following pairs were successfully operated, Ram & Laxman 1992, Anjali & Geetanjali 1993, Rekha & Surekha 1998 and Veena & Vani 2004;
Abigail and Brittany Hensel, (1990-), born in Carver County, Minnesota, United States of America, dicephalic conjoined twins.
Lotti and Rosemarie Knaak (craniopagus) born in Hamburg,Germany.

[edit] Types of conjoined twins

There are several different types of conjoined twins:

-- Diplopagus: Conjoined twins joined equally with near complete body, only sharing a few organs.

-- Heteropagus: Conjoined twins joined unequal usually resulting in parasitic 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).
- Xiphopagous: bodies fused in the xiphoid cartilage, e.g., Chang and Eng
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%).
- Craniopagus parasiticus': A second bodiless head attached to the head.
Dicephalus: Two heads, one body with two legs and two, three, or four arms (dibrachius, tribrachius or tetrabrachius, respectively.) Abigail and Brittany Hensel, 17-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 heteropagus 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] Separation

Surgery to separate conjoined twins may range from relatively simple to extremely complex, depending on the point of attachment. Most cases of separation are extremely risky and life-threatening. In many cases, the surgery results in the death of one or both of the twins, particularly if they are joined at the head. Saudi Arabia holds the most successful separation rate. The U.A.E. currently has the lowest success separation rate.