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Craniopagus twins
Craniopagus twins are conjoined twins who are fused at the cranium.〔Todorov, A.B., K.L. Cohen, V. Spilotro, and E. Landau. "Craniopagus Twins." Journal of Neurology, Neurosurgery and Psychiatry (1974): 37. Web〕 This condition occurs in about 10-20 babies in every million births in the United States. Among this small group, cephalic conjoining, or craniopagus twinning, represents the rarest of congenital abnormalities only accounting for 2-6% of all conjoined twins. Additionally, conjoined twins are genetically identical and always share the same sex. The union in craniopagus twins may occur on any portion of the calvarium, but does not include either the face or the foramen magnum. The thorax and abdomen are separate and each twin has its own ubilicus and umbilical cord. The union may involve the entire diameter of the head or only a small portion. This suggests that although there are many different kinds of variabilities already known in the scientific community, there are an infinite amount of variations that can occur. Most of these variations are based on the rotation of one twins' skull to the other and in fact, the different phenoytpic sub-groups of craniopagus twins are based on all these rotational conformations. Each of these factors (rotation, spot of union) affect the development of the brain, the vascular system within the brain and overall wellness of life both of the twins have outside the womb. Relatively few craniopagus twins survive the perinatal period- approximately 40% of conjoined twins are stillborn and an additional 33% die within the immediate perinatal period, usually from organ abnormalities and failure.〔Browd, Samuel L., James T. Goodrich, and Marion L. Walker. "Craniopagus Twins." Neurosurgery Pediatrics 1.20 (2008): n. pag. Web〕 However 25% of craniopagus twins survive and can be considered for a surgical separation and several attempts occur yearly worldwide. In the last-half century the many advances in medicine including brain imaging, neuro-anaesthesia and neurosurgical techniques have proven that a successful outcome is possible following separation of total craniopagus twins.
== Early history ==
Conjoined twinning is one of the oldest known birth defects in history and examples with human’s fascination with twins is extremely evident throughout historical literature. The Gemini constellation, known in Greek mythology as Castor and Pollux, is arguably one of the best known sets of twins of all time.〔Squair, Jordan. "Craniopagus: Overview and the Implications of Sharing a Brain." (2012): n. pag. Print.〕 In history, Castor and Pollux fought Greek battles alongside other famous war heroes like Herkules and Achilles. The Greeks held these twins in high standing and they were seen not just as warriors but as Gods. Although there are cases of conjoined twins dating back to as early as the 10th century, it was not until 1491 that the first case was documented.
Apart from that, Sebastian Munster’s ''Cosmographia universalis'' provides the true first account of craniopagus twins who happened to live for ten years, exceeding many expectations during that time.〔Walker, Marion, and Samuel Browd. "Childs Nerve System." Childs Nerve System. 20. (2004): n. page. Web. 19 Nov. 2012.〕 He describes the set of twins as being a unique malformation and a punishment from their mother’s mistake. Furthermore in Ambroise Pare’s book, “On Monsters and Marvels”, various types of “supernatural” twinning are illustrated and described as “monstrous and marvelous creatures that proceed from the judgment of God.” This published history suggests that conjoined twins, and in specific craniopagus twins, were viewed as literal monsters during that era. However, new technology, surgical interventions and successful operations has worked on removing these ancient stereotypes and given conjoined twins the social acceptance they deserve.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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