Craniopagus Twins

Craniopagus twins are conjoined twins who are fused at the cranium. 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. 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.