leibel conjoined twinsdoc - Wikispaces.doc by tongxiamy

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									Jennifer Leibel

       Twins Krista and Tatiana Hogan have been a topic of intense fascination and

research ever since their birth four a half years ago. This is because they are not normal

twins; they are conjoined at the head. The technical term to describe this condition is

craniopagus. It is believed that these girls in particular are joined by a thalamic bridge,

which links one of their thalami to the other one. This in itself creates a whole other

interest in the twins because along with the physiological problems that accompany this

kind of condition, they seem to share some of the same senses.

       Like all conjoined twins, Krista and Tatiana’s parents were faced with a difficult

decision at their birth; should they be separated? They decided not to go through with the

surgery because it would have been too risky because they would have had to split the

thalami, which would cut too much normal tissue. In the case of the Hogan twins,

Tatiana’s heart and kidney carry the brunt of the blood pumping for both girls. Because

of this, she is smaller and frailer than Krista. However, they are both developmentally

delayed by one year. They also have a shorter corpus callosum than normal, and their

cerebral hemispheres differ in size. In the past, both girls have suffered from seizures, but

are on medication and have not had one in over a year. Other problems that the girls have

include severe eye problems, and for Tatiana, high blood pressure and bad teeth. While

it’s interesting to see the differences between their health and the health of other twins or

children, what is really exciting scientists is their seemingly unique abilities compared to

others. The girls are known for showing off tricks such as Tatiana being able to see what

Krista would see if her eyes were open. It has been reported that a prick from a needle on

one girl makes both cry, and a pacifier in the mouth of one also soothes the other.
Scientists all have different theories about why this could be, but the main source of these

happenings is the fact that they are connected at the thalamus, which acts as a relay

station for the senses. This makes it seem possible that one girl’s senses could cross with

the other, but it is still up for speculation.

        While Krista and Tatiana are the newest interest for people everywhere, the first

recorded conjoined twins are Mary and Eliza Chulkhurst, born in 1100. It is said that they

were joined at both the shoulder and the hip. These are just two examples of conjoined

twins. There are many different types, each accompanied by certain physiological

problems and some more common than others. Twins fused from the upper chest to the

lower chest are called thoraco-omphalopagus. These twins share a heart, and in some

cases may share a liver or part of the digestive system. Thoracopagus twins are twins

joined from the upper thorax to the lower belly. In these cases, the heart is usually

involved. Another common type of conjoined twins is omphalopagus twins. This means

that they are fused at the lower chest and instead of the heart being involved, they often

share a liver, diaphragm, digestive system, and other organs. Another less common type

of conjoined twins is dicephalic parapagus twins, which means that they are conjoined

twins with separate heads but one body. This type of twin can be seen in the case of

Abigail and Brittany Hensel. They have two spines and two spinal cords, two hearts, two

stomachs, and three kidneys. However, they share two legs and two arms. This has

obviously created a struggle for the girls, but they so far have been able to live as normal

lives as possible given their situation.

        While scientists have advanced their studies of conjoined twins, they still do not

understand everything there is to know about them. Cases such as Tatiana and Krista
Hogan will continue to amaze people everywhere with their tricks and sensations. It will

definitely be interesting to see them grow up and see how they adapt to the outside world,

since they have already developed skills unique to their own condition.

								
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