Separated Twins' Zest Is Contagious

Five years ago, "Good Morning America" introduced viewers to the Ibrahim twins, two little boys from Egypt.

Conjoined at the head, the brothers underwent a massive and risky operation to be separated, which took place four years ago next week. Now they are back in Texas for a checkup, and they continue to amaze us.

Mohammed and Ahmed Ibrahim flew 24 hours from Cairo to Dallas, two tough 6-year-olds without a lick of jet lag.

When "Good Morning America" first met them at the age of 2, the Ibrahim twins were conjoined at the brain -- a condition with one in 2 million odds.

Their parents were warned that both twins survive in only 10 percent of surgeries.

Dr. Kenneth Salyer of the World Craniofacial Foundation, along with more than 50 physicians, anesthesiologists and nurses, spent 34 hours performing a daring operation to achieve the impossible.

ABC News was granted exclusive access to the twins when they reunited with the man who led the effort to separate them. They grin ear to ear nonstop with or without their protective head gear. When they saw Salyer, they gave him high-fives.

"There is a little softness here but it feels good," Salyer said as he massaged Mohammed's head.

Doctors agree that it is too dangerous to do any further reconstructive surgery on the twins' skulls. If they do, the boys' heads will be a bit misshapen for the rest of their lives.

Mohammed and Ahmed's enthusiasm for the gift of freedom is infectious.

Soon after the operation Ahmed was unable to walk, but now he can't be stopped. When he starts singing his songs or gets the giggles, it's contagious. And his brother Mohammed is now a typical 6-year-old, in other words, a blur of motion.

The boys are now undergoing dozens of tests and are making spectacular progress.

For more information on the Craniofacial Foundation click here.