Updated

Arizona Rep. Gabrielle Giffords remains in intensive care following surgery at the University of Arizona Hospital for a gunshot wound to the head at close range.

Dr. Manny Alvarez, senior managing health editor of FoxNews.com, said surviving a gunshot wound to the head is rare, but not unheard of – and Giffords is in for a long fight.

Alvarez said the survival rate of a gunshot wound to the head is about 5 percent – and 3 percent of those who do survive will always have a neurological deficiency, such as memory loss or a lack or motor skills.

“It all depends on where the bullet goes,” he said. “Your best chance of survival is from front to back, if you get shot side to side, the survival rate is less, and it all depends on the damage the brain has.”

Giffords’ friend, state Sen. Linda Lopez, confirmed the bullet entered Giffords’ head at her temple and exited through her forehead. Lopez said Giffords was responding to commands before surgery but is not sure what Giffords' long-term prognosis is.

“If the bullet goes through both hemispheres and leans toward the base of skull, that is where most of the vascular tissues are, and that can be a deadly result,” Alvarez said. “If the bullet goes through both hemispheres, but there is a clean exit wound, the patient can be lucky and there might not be any significant damage. Of course, the best prognosis is when the bullet affects only one hemisphere. Nonetheless, any gunshot wound to the head is going to leave residual side effects.”

Alvarez said the next three to four days is considered the most critical for Giffords, and recovery could take years to achieve.

“Doctors carefully opened the skull and looked for any type of bleeding and then cauterized blood vessels,” Alvarez said. “Patients are kept under anesthesia for three to four days to monitor brain swelling, which is one of the complications of this surgery."

Alvarez pointed to the story of a British soldier who survived a gunshot wound to the brain but learned to walk and talk again and in October 2010 was quoted in the The Sun as saying, “They say I’m a walking miracle.”

The soldier, Liam Brentley, was shot near the ear, and the bullet came out the other side of his head, pinging a wall, according to the U.K. newspaper.

Brentley is deaf in one ear and has some memory loss.