Transcript document
By: Gina Caprara • Joined by a portion of the skull, with distinctly separate necks and bodies. Separation is very risky since these twins can share parts of the brain, as well as blood circulation. • Craniopagus twins are further classified by the portion of the skull which is shared: – Vertical craniopagus - joined at the top of the head with bodies at a 180-degree angle to one another – Occipital craniopagus - joined at the back of the head – Frontal craniopagus - joined at the forehead – Parietal craniopagus - joined at the side of the head • Joined at the upper chest, from the clavicle to the sternum, each with their own separate heads, arms and legs. • The heart is always involved in the conjoinment; some thoracopagus twins have two separate hearts in a single pericardium (heart sac), while others share a single, malformed heart. • Thus separation is extremely risky and both twins often die, despite doctors efforts. • Joined at the xiphoid process (part of the sternum) and usually linked only by cartilage and soft tissue. • These twins share no vital organs but often have conjoined livers. They are by far the easiest to separate. • “Fusion Theory”- twins become conjoined after the fertilized ovum initially splits into identical twins. While lying side-by-side in the uterine wall, the two embryos become fused together. A human embryo, in its earliest stages, consists of three layers of cells. These cells "seek out" cells of the same type and thus bond together to form individual organs. When two newly-separated identical twin embryos are lying in close proximity to one another, sometimes signals get mixed and cells will attach to other cells of the same type, but that belong to the other twin. Continued… • The “Fission theory" states that conjoined twins occur when a fertilized ovum begins to split into identical twins, but is somehow interrupted during the process and develops into two partially formed individuals who are stuck together. • Twins joined at the sacrum at the base of the spine have a 68 percent chance of successful separation, whereas, in cases of twins with conjoined hearts at the ventricular level, you most likely will not survive. • Doctors can use magnetic resonance imaging, ultrasound and angiography to find out what organs the twins share • Doctors must be able to determine how the twins organs function, in order to perform surgery • After separation, most twins need intensive rehabilitation because of the malformation and position of their spines.