When Rep. Gabrielle Giffords was shot Saturday, the bullet likely entered the front of her skull, passed through the left side of her brain and exited the back. Amazingly, she now has a "101 percent chance of survival" according to Dr. Peter Rhee, the director of medical trauma at her hospital. Rhee is also optimistic that she's not going to be in a vegetative state in the months and years to come. If she continues to recover, as doctors predict, she will have survived an injury that is fatal 90% of the time. To get a better sense of the dynamics of a gunshot wound to the head and the recovery process, we've rounded up interviews and reports from medical experts across the web. Here's how Giffords's body reacted to the bullet and what her prospects are for returning to politics:

  • First Impact  "A bullet first destroys tissue that lies in its path, which for Giffords was on the left side of the brain," explains Erika Check Hayden at Nature News. "But it also damages neurons that don't lie directly in its path, because it is trailed by a pressure wave that transfers the energy of the bullet into the surrounding brain tissue. This pressure wave activates all the neurons through which it passes. The neurons then attempt to restore their resting electrochemical balance by absorbing water, resulting in brain swelling."
  • The Craniectomy  "During surgery, the doctors at Arizona's University Medical Center removed a large portion of Giffords' skull to allow the brain to swell without being damaged," explains Tracy Staedter at Discovery News. "They also used drugs to induce a coma, which slows the metabolism and blood flow in the brain, decreasing pressure."
  • Her Response  "Over the last several days, Ms. Giffords has repeatedly given nonverbal responses to her doctors' commands, they said, and CAT scan X-rays have shown that there is no swelling, which continues to be the most serious threat," reports Jennifer Medina at The New York Times. "So far, doctors said, she has shown only slight movement on the right side of her body, raising questions about her functional neurological status. Doctors again declined to give some specific details about Ms. Giffords."
  • Sometimes Bullet Wounds Are Less Pernicious "Neurosurgeons distinguish between 'penetrating' injuries, such as bullets that go through the brain, and 'blunt' injuries, which refer to the trauma of hitting one's head against an object or the floor," reports Elizabeth Landau at CNN. "A bullet creates a focused wound to the brain, concentrated in one area, while a concussion or other blunt injury creates more diffuse harm ... Because it's easier to know which tissue is damaged, a focused wound can be better from the surgeon's point of view ... However, in some cases, the blast wave of a bullet can spread through brain tissue, impacting multiple areas."
  • Bob Woodruff Comparison  The ABC News anchor faced a similar head injury via a roadside bomb in Iraq. Woodruff, who continues to report for ABC, says the chances for Giffords's recovery look better than his did at the time: "In one way her case is more hopeful. She responded to verbal commands by the doctors and reacted by squeezing their finger, indicating she understood, although she could not speak. I never heard the words and never squeezed my doctors' fingers when they tried to get me to respond."
  • Long-Term Complications Erika Check Hayden at Nature News explains the potential lasting effects:
Even if Giffords recovers most of her movement and thinking skills, she could suffer from a range of other lifelong complications; for example, she will have an increased risk of developing dementia or Parkinson's disease. Up to 50% of people who have a penetrating brain injury also go on to develop epilepsy, perhaps because bleeding in the brain after an injury exposes it to high doses of seizure-associated chemicals called haemosiderins, which arise as haemoglobins in the blood break down. Many patients with injuries to the left sides of their brains also experience depression, because a region on the left front of the brain is involved in mood control.
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