Congresswoman Gabrielle Giffords
© unknownCongresswoman Gabrielle Giffords
It has been almost three days since Congresswoman Gabrielle Giffords was shot in the head in Arizona. Tuesday morning she remained in critical condition at a hospital in Tucson. Dr. Max Gomez reports on how she was able to survive such a devastating injury and what will determine how much function she may recover.

Giffords is heading into the most critical time in her recovery, when her brain will usually reach its maximum swelling after the gunshot wound.

"The brain will swell. If the brain is within the closed box of the skull, it has nowhere to swell, and it starts compressing or injring the normal, good part of the brain," said Dr. Philip Stieg of New York-Presbyterian/Weill Cornell.

To allow the brain to swell, surgeons actually removed a large portion of the congresswoman's skull and reportedly have stored it in the refridgerated bone bank for later replacement after the brain swelling subsides.

That bone may be contaminated after the gunshot and doctors may use a prosthetic bone later.

The immediate concern was surgery. She was in the operating room within 38 minutes of reaching the hospital. The bullet would have dragged bits of bone, hair and scalp into the brain which had to be cleaned out to prevent infection and any bleeding had to be controlled.

The severity of the brain damage the congresswoman suffered depends entirely on the path of the bullet.

"If you can imagine a bullet coming in on this side and it goes through this area, the motor strip, the person would have loss of function, on the right hand side of the body, speech cortex in this part of the brain here, they would have loss of speech, this part of the brain, the temporal lobe, loss of memory, short term memory," Dr. Stieg said.

Giffords was in a drug-induced coma to slow her brain metabolism and allow it to rest, although doctors periodically bring her out of the coma to check her neurologic status, asking her to respond to simple commands such as squeeze a hand or hold up fingers.

The fact that she can suggests that the bullet may have missed certain critical brain areas and that they are communicating with each other, but again, secondary damage that can come from brain swelling and inflammation could still cause damage to those areas.

It will be weeks before doctors can really assess the full extent of the damage and Dr. Stieg told Dr. Gomez that recovery could take at least a year, or perhaps several years.

Can she continue to recover function even after she's out of the hospital? Yes, and that's a somewhat new understanding of brain function.

Doctors now know that even an adult brain can form new connections that can restore function long after an injury. It used to thought that this kind of what's called "plasticity" was only present in children's brains but it can also happen in adults.