| Conjoined twins | |
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| Classification and external resources | |
A painting of Chang and Eng Bunker, circa 1836 |
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| ICD-10 | O33.7, Q89.4 |
| ICD-9 | 678.1, 759.4 |
| DiseasesDB | 34474 |
| eMedicine | ped/2936 |
| MeSH | D014428 |
Conjoined twins (aka Siamese twins) are identical twins whose bodies are joined in utero. A rare phenomenon, the occurrence is estimated to range from 1 in 50,000 births to 1 in 100,000 births, with a somewhat higher incidence in Southwest Asia and Africa.[1] Approximately half are stillborn, and a smaller fraction of pairs born alive have abnormalities incompatible with life. The overall survival rate for conjoined twins is approximately 25%.[2] The condition is more frequently found among females, with a ratio of 3:1.[1]
Two contradicting theories exist to explain the origins of conjoined twins. The older theory is fission, in which the fertilized egg splits partially. The second and more generally accepted theory is fusion, in which a fertilized egg completely separates, but stem cells (which search for similar cells) find like-stem cells on the other twin and fuse the twins together. Conjoined twins share a single common chorion, placenta, and amniotic sac, although these characteristics are not exclusive to conjoined twins as there are some monozygotic but non-conjoined twins that also share these structures in utero.[3]
The most famous pair of conjoined twins was Chang and Eng Bunker (Thai: อิน-จัน, In-Chan) (1811–1874), Thai brothers born in Siam, now Thailand. They traveled with P.T. Barnum's circus for many years and were billed as the Siamese Twins. Chang and Eng were joined by a band of flesh, cartilage, and their fused livers at the torso. In modern times, they could have been easily separated.[4] Due to the brothers' fame and the rarity of the condition, the term "Siamese twins" came to be used as a synonym for conjoined twins.[5]
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Conjoined twins are typically classified by the point at which their bodies are joined. The most common types of conjoined twins are:
Other less-common types of conjoined twins include:
Surgery to separate conjoined twins may range from relatively simple to extremely complex, depending on the point of attachment and the internal parts that are shared. 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. This makes the ethics of surgical separation, where the twins can survive if not separated, contentious. Dreger found the quality of life of twins who remain conjoined to be higher than is commonly supposed.[9] Lori and George Schappell are a good example.
Recent successful separations of conjoined twins include that of the separation of Ganga & Jamuna Shreshta in 2001, who were born in Kathmandu, Nepal in 2000. The 97 hour surgery on the pair of craniopagus twins was a landmark one which took place in Singapore; the team was led by neurosurgeons, Dr. Chumpon Chan and Dr. Keith Goh.[10] Ganga Shrestha died at the Model Hospital in Katmandu in July 2009, at the age of 8, three days after being admitted for treatment of a severe chest infection.
In 2003 two women from Iran, Ladan and Laleh Bijani, who were joined at the head but had separate brains (craniopagus) were surgically separated in Singapore, despite surgeons' warnings that the operation could be fatal to one or both. Both women died during surgery on July 8, 2003.
A case of particular interest was that of Rosie and Gracie Attard, two conjoined twins from Malta who were separated by court order in Great Britain over the religious objections of their parents, Michaelangelo and Rina Attard. The surgery took place in November, 2000, at St Mary's Hospital in Manchester. The operation was controversial because Rosie, the weaker twin, would die as a result of the procedure as her heart and lungs were dependent upon Gracie's. (The twins were attached at the lower abdomen and spine.) However, if the operation had not taken place, it was certain that both twins would die.[11][12]
The Moche culture of ancient Peru depicted conjoined twins in their ceramics dating back to 300 CE.[13] The earliest known documented case of conjoined twins dates from the year 942, when a pair of conjoined twin brothers from Armenia were brought to Constantinople for medical evaluation.
In Arabia, the twin brothers Hashim ibn Abd Manaf and 'Abd Shams were born with Hashim's leg attached to his twin brother's head. Legend says that their father, Abd Manaf ibn Qusai, separated his conjoined sons with a sword and that some priests believed that the blood that had flown between them signified wars between their progeny (confrontations did occur between Banu al'Abbas and Banu Ummaya ibn 'Abd Shams in the year 750 AH).[14] The Muslim polymath Abū al-Rayhān al-Bīrūnī described Siamese twins in his book Kitab-al-Saidana.[15]
The English twin sisters Mary and Eliza Chulkhurst, who were conjoined at the back (pygopagus), lived from 1100 to 1134 (or 1500 to 1534) and were perhaps the best-known early historical example of conjoined twins. Other early conjoined twins to attain notice were the "Scottish brothers", allegedly of the dicephalus type, essentially two heads sharing the same body (1460–1488, although the dates vary); the pygopagus Helen and Judith of Szőny, Hungary (1701–1723), who enjoyed a brief career in music before being sent to live in a convent; and Rita and Cristina of 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 because England had already 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.
Names listed in boldface are of twins who have been separated.
\*Rose and Grace Attard ("Mary and Jodie"), Maltese twins joined at spine, born October 2000. Separated in Great Britain by court order against the wishes of their parents, because Mary could not survive independently.[16] Mary died upon separation.
.*Carl and Clarence Aguirre, born vertical craniopagus in Manila on April 21, 2002 were successfully separated using a staged procedure performed over the course of 10 months at the Children's Hospital at Montefiore in New York City. The separation occurred on August 4, 2004.[17]
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