Krista and Tatiana Hogan

Krista Hogan and Tatiana Hogan (born October 25, 2006) are craniopagus conjoined twins. They are joined at the top, backs, and sides of their heads. They were born in Vancouver, British Columbia, Canada, and are the only unseparated craniopagus twins currently alive in Canada. They live with their mother, Felicia Simms, in Vernon, British Columbia and often travel to Vancouver for care at BC Children's Hospital and Sunny Hill Health Centre for Children. Their father is Brendan Hogan. Tatiana and Krista have one older sister, Rosa; one older half-brother, Christopher; and one younger sister, Shaylee. Their grandmother, Louise McKay, is involved with raising them.

Birth
Based on statistics, the Hogan twins were given a 20% chance of survival at birth. At birth, they were described as "wriggly, vigorous and very vocal." Krista and Tatiana weighed twelve and a half pounds, not six and a half pounds as reported by some media outlets, when they were born by caesarean section.

Early infant life
Tests on the twin girls in April 2007 showed that Tatiana's heart was working harder than her sister's and that she had high blood pressure because of it&mdash;her heart supplies part of the blood to Krista's brain. Tatiana is smaller and less robust than Krista. A surgery was planned to give Krista's heart a "jump start" so Tatiana's heart would not have to work so hard.

The twins' nervous systems are highly interconnected; their doctors reported that when one of the girls is tickled, the other jumps, and that putting a pacifier in the mouth of one child could cause the other to stop crying.

Their birth, potential separation, depth of community support and their family's financial situation have been subject to significant media coverage in Canada. The twins and their mother were also guests on The Tyra Banks Show in the US.

In August 2007, it was declared the girls cannot be separated, due to the likelihood of the surgery killing or paralyzing one or both girls.

The family reduced the twins' public profile due to a contract giving exclusive access to a documentary crew for National Geographic and the Discovery Channel UK. The show was broadcast first in Britain in spring 2010, and then aired in June in Canada and the U.S.

The documentary followed a year in the twins' life and included a "particularly poignant" meeting between the family and Lori and George Schappell, 49, the world’s oldest twins to survive being joined at the head.

There is suspicion that they can see through each other's eyes, due to brain conjoining. In their brains their thalamuses are joined.

Progression to childhood
In January 2009, a documentary was filmed which reported on Tatiana and Krista Hogan, and followed their progress up to their 3rd birthday. This documentary was released and aired in October, 2010. In this documentary, it was confirmed that Tatiana and Krista shared a thalamus which connected their brainstems. Through this shared brain tissue structure and the interconnected neurons one brain receives signals from the other brain and vice versa. This documentary also reported on experiments which were carried out which confirmed that visual cortex signals were received at the other brain. So in effect, one twin could "see" what the other twin was seeing, making them unique even among craniopagus twins.

At this time, Tatiana suffered from a sleep apnea condition which occasionally caused her to stop breathing for up to 20 seconds. A sleep apnea specialist, Dr. Fred Kozak, performed surgery on Tatiana and was able to successfully treat her sleep apnea. Not long after the surgery, Tatiana's heart shrank to a more normal size and her heart rate dropped such that it no longer carried all of the burden of circulating blood for both brains.

The documentary reports that Tatiana and Krista are progressing well, and have achieved all the normal childhood milestones, such as walking, talking, and counting.