The path of the shooter's bullet, traveling straight through the left side of the brain, left doctors treating U.S. Rep. Gabrielle Giffords guardedly optimistic that she could make a good recovery.
The bullet -- from a semiautomatic pistol -- entered the back of Giffords head and exited the front, without crossing into the right hemisphere of the brain, according to Michael Lemole, MD, chief of neurosurgery at University Medical Center in Tucson, where Giffords was rushed after the shooting at a Tucson, Ariz., supermarket on Saturday.
The fact that the bullet did not cross hemispheres was one of the several positive variables involved in assessing the probability of the congresswoman's recovery, Keith Black, MD, chairman of neurosurgery at Cedars-Sinai Medical Center in Los Angeles, told 鶹ý.
Six people died during the shooting spree at a constituent meeting and 14, including Giffords, were wounded. Police have charged Jared Lee Loughner, 22, with the shooting.
The left hemisphere controls several functions, including language, motor movement on the right side of the body, vision, personality, and memory, any of which could be affected.
As she is still in a medically-induced coma, it is too early to tell what types of deficits -- if any -- Giffords might have, but initial reports about the shooting indicate several positive prognostic factors, Black, who is not involved in Giffords' treatment but who has treated patients with wounds similar to the congresswoman's, said.
Published reports indicate that Giffords was able to respond to a request immediately after the shooting to squeeze the hand of a staff intern who rushed to her side. Doctors at University Medical Center also reported that she was responsive before surgery and after surgery when they lightened the anesthesia.
That indicates that the language area of the brain is still functioning at least partly, Black said.
Surgeons have also reported that Giffords does not have increased weakness on the right side compared with the left, which may indicate that she does not have any major motor impairment or paralysis, another positive prognostic sign, Black said.
The trajectory of the bullet is another critical piece of information when assessing prognosis, according to Black.
He said that, based on reports from the Arizona surgeons, it appears that the bullet avoided areas of the brain responsible for language and motor movement and also did not travel through the ventricles.
A high velocity bullet, such as one from an AK47, would be expected to do more damage than a lower-velocity bullet from a pistol, as was used in Giffords' shooting.
In addition, the bullet exited the skull, which is also a positive sign, Black said.
He said good emergency treatment is important as well following an injury like Giffords', including protection of the airway to ensure the brain continues to get oxygen and controlling blood pressure.
According to published reports, the intern who attended to Giffords after the shooting raised her head to allow her to breathe, and placed pressure on her wounds.
She was rushed to the level I trauma center at University Medical Center and underwent surgery quickly, another factor that went right for Giffords, according to Black.
During the operation, surgeons would have removed any accumulated blood in the brain, stopped bleeding, and removed any hair and skin fragments introduced by the bullet, according to Black.
Lemole reported removing a large piece of Giffords' skull to give her brain room to swell.
In addition to infection and delayed bleeding, swelling is one of the most critical factors her doctors will be monitoring over the coming days, Black said.
Pressure in the brain can be controlled in a number of ways, he said, including hyperventilation and the use of mannitol to draw water out of the brain or steroids to lower pressure.
At a press conference Monday - Giffords' postoperative day two - Lemole said that CT scans have not shown any signs of progressive swelling, noting that the congresswoman no longer needs medications to control the pressure.
"We're not out of the woods yet," Lemole said. "That swelling can sometimes take three days or five days to maximize, but every day that goes by and we don't see an increase, we're slightly more optimistic."
Black said that when surgeons start to bring Giffords out of the medically-induced coma will depend on the pressure in the brain, CT scans, and physical examinations. Doctors will want to see that she can maintain pressures in the normal range.
"I think the likelihood that she will survive is high," he said. "The probability that she will have a complete recovery with no deficits, I think it's just too early to really tell until she gets off the respirator and one can get a better neurological examination."
He said it would probably take about a week -- after she is taken off the respirator and is brought out of the medically-induced coma -- to get preliminary examinations of how Giffords' vision, speech, and memory are functioning. About two-to-three months later, probably after she has completed rehabilitation, doctors will perform more detailed neurocognitive tests to look for more subtle deficits.
At a press conference, Peter Rhee, MD, MPH, medical director of trauma and critical care at University Medical Center, also assessed Giffords' prognosis optimistically.
"Overall, this is about as good as it's going to get," he said. "When you get shot in the head, and the bullet goes through your brain, the chances of you living is very small, and the chances of you waking up and actually following commands is even much smaller than that. So this so far has been a very good situation."