Congresswoman Gabrielle Giffords brain injury and bullet wound was not fatal, because the doctor's got to it in time to treat it aggressively. This congresswoman was active on foreign affiars-related committees and had visited Iraq, where she saw first hand what was happening to our troops, with so many truamatic brain injuries from roadside explosions. Doctor's have learned, as a result of this wartime experience, to respond rapidly and aggressively to severe head trauma. Their rapid and aggressive response likely meant the difference between life and death. Swelling of the brain untreated could have shoved her brain down and cut off basic life functions.
In Ms. Giffords case, the bullet wound entered and exited on the left side of the brain, and much of the injury was to the left tempral lobe, although some reports have suggested that there was some left frontal damage as well. The left side of the brain is called the dominant hemisphere, and it is responsible for many of the things we do in civilized society, including speech and sequnetial tasks and processing of information in a linear fashion. It is the more logical part of the brain, although decision making is usually done at the frontal areas. The temoral lobe, on the left side, where most of the damage was done, is very much an area that is responsible for speeech and language.
The right hemisphere, in contrast, is the side of the brain that deals with the connections between things, and is often referred to as the side of the brain that is tasked with creativity, music and art. It is also tasked in general with more of the nonverbal aspects of thinking, and it controls motor function on the left side of the body, whereas the left side of the brain, wheren she was injuted typically handles movements on the right side of the body.
Reports that Congresswoman Giffords can respond to simple verbal directions by squeezing the doctors hand (both before and after surgery) are encouraging. Not only does that suggest that she retains control of willfull motor functions (on at least one side of her body), but also that she understands at least simple speech commands. The damage to the left temporal lobe is most likely to effect speech, because the Wernicke's area of the temporal lobe is most responsible for speech.
So the question remains will she be able to speak? The absence of the ability to produce speech is one type of speech aphasia, and mostly it is governed in a more frontal part of the left side known as Broca's area. If she is not able to speak, that would not not mean that she could not communicate. If she has some initial damage in the temporal area, as reports suggest, she may well have some difficulty that goes beyond giving speeches, indeed she may have trouble with simple things like naming a coffee pot or a person (anomia) or fluency problems where such conditions lead to nonsense and made up words, lengthy speaking that makes even less sense than the typical speech of a politician.
Aphasia, if there is some in congresswoman Giffords, can be worked on in rehabilitation, and there are alternative ways to communicate while you get your speech back, if she has to do that. Of course I have not seen or evaluated Ms Gifford and I am relying on news accounts from interviews with her doctors, and I have not got any special diagnostic information. I am simply providing education about the kinds of problems we expect to see with traumatic brain injuries from wounds.
Realize that the brain has a great deal of plasticity, meaning it can adapt. One girl who had half of her brain removed surgically eventually managed to have nearly all of her brain functions handled by the other, remaining side. This plasticity is most evident when the brain injury or wound occurs in a young healthy person like the congresswoman. Congresswoman Gifford from Arizona is still quite young and healthy, and this increases the odds or a rapid recovery, which would still take in a good scenario several months. A full recovery is possible, but more would need to be known of how extensive the damage was to her brain, and whether or not she will have much aphasia.