dr. nasser, dr. mandu and the medical team take the twins on to an airplane bou. then arriving in dallas with his team and two tired little boys, nasser takes a part of this load from his own children and presents the case to dr. kenneth sawyer. coming up -- >> the most difficult case that i have ever had to deal with. >> doctors face a choice. whether to let the twins go through life joined at the head or risk death by trying to give them a more normal life. [ male announcer ] you've climbed a few mountains during your time. and having a partner like northern trust -- one of the nation's largest wealth managers -- makes all the difference. our goals-based investment strategies are tailored to your needs and overseen by experts who seek to maximize opportunities while minimizing risk. after all, you don't climb a mountain just to sit at the top. you lookround for other mountains to climb. ♪ expertise matters. find it at northern trust. ♪ you know rheumatoid arthritis means pain. but you may not know it can also mean destruction. not just of your joints, but of the