With brain injuries, as with many other severe traumas to the body, the worst damage is often done not by the initial wound but by the body’s attempt to heal it. Inflammation—in which immune cells rush in to try to repair the injured tissue and remove the dead or dying cells— can often do harm as well as good, resulting in swelling that can create potentially fatal pressure in the tight confines of the skull.
I spoke with Dr. Nirit Weiss, a neurosurgeon at New York’s Mt. Sinai hospital, about treating patients like Congresswoman Gabrielle Giffords, who was shot in the head in Saturday’s massacre in Arizona. Weiss has treated hundreds of shooting victims. (More on Time.com: See images of the mourners from the Tucson shooting)
What do you do when someone comes into the hospital after an injury like this?
The first thing is to evaluate the level of functioning because that has tremendous prognostic value. The level of function at the time of injury or admission can give you a clue about what parts of the brain are irreversibly injured.
[Then] we basically stabilize [them] and take them right to a CT scanner to see what the trajectory of the bullet was and what kind [of injury there is]. We look for hematomas [pockets of blood] that follow the trajectory and for secondary swelling. The majority of our focus is on secondary injury.
[If the injury appears survivable], we usually go to surgery for a couple of reasons. There’s typically lots of debris [like parts of the] scalp and hair that have been dragged into the brain, so we do at least a fairly superficial surgery to remove that debris and try to reduce the chances of infection.
If the location of the bullet or fragments is relatively superficial, we will get in and take it and out, but most commonly [these fragments are] deep and we leave them alone. If there is a massive blood clot that threatens survival, that’s another reason to do surgery and we go in and remove it.
Why do you remove parts of the skull?
For most people, the secondary injury is what compromises function. A secondary injury [related to swelling] could kill an otherwise salvageable patient. Our main task is to try to prevent secondary hematomas and swelling and infection.
The brain cells killed by the bullet can never recover. But the body responds to every injury like a bruise, with inflammation that leads to swelling in the surrounding tissue that was not injured. In a closed skull, it’s a contained space, it’s not elastic at all and swelling can lead to cell death. Unless you allow for expansion of the brain by taking off some of the skull, that swelling leads to increased pressure and to cell death in areas that didn’t have to die.
The thing we can help with is that physical pressure. By relieving that pressure you do dramatically alter the outcome. (More on Time.com: Controlling Your World With a Single Neuron)
We have these patients [after surgery], their scalp is closed but you can feel the brain underneath it swelling. It gets worse and worse for the first 72 hours and then you can feel the bandage around the scalp gets softer as the brain shrinks.
Congresswoman Giffords was reportedly able to respond to commands after the injury and when she got to the hospital. What does that say about her chances of recovery?
That [gives her] a very good prognosis. It indicates that the primary irreversible injury did not hit the parts of the brain responsible for the comprehension of speech, for consciousness, for [some motor function]. Those have to be intact to allow her to respond to a command like moving her finger. But she can develop brain swelling to subsequently compromise those areas if [treatment] is not successful.
That gives her the best possible start, but next the few days are still crucial. And she may be extremely brain injured despite being able to do that.
What are some other signs that help you determine how she is likely to do? The reports say the bullet traveled from the back of the left side of her head and exited the front.
It’s really hard to know from the nontechnical terms [used in the reporting on her case]. There are certain indicators for bad outcomes. If the bullet went from back to front, it could indicate that there are multiple lobes of the left side of the brain involved. If more than one lobe is involved, that is a worse prognosis. (More on Time.com: After Tucson: Why Are the Mentally Ill Still Bearing Arms?)
That said, you do see people get really lucky. If the bullet went high and superficial, it can go from back to front and you lose [relatively few] cells. When that happens, we say wow that guy is lucky, he won the lottery, but in general an injury involving multiple lobes going from front to back has a poor prognosis.
The fact that she responds to commands like “show me two fingers,” that shows comprehension of speech, motor function, consciousness, thinking. But does it mean she will retain a high enough level of functioning to serve? Very possibly not. Even if she does return to normal functioning, she won’t return in three months time. A very prolonged rehabilitation is likely.
Could she still be paralyzed?
Based on what they are telling us, she might be completely paralyzed on the right side, she might have been squeezing someone’s hand with her left hand. The left side of the brain controls the right side of the body.
Why is she in a medically induced coma?
It’s hard to say without knowing the details, but probably because giving very deep sedatives is one of the ways to take pressure off of the brain. It decreases the metabolism of the brain and blood flow and can help decrease pressure and help the survival of neighboring brain cells.
Have you had similar cases where people did recover?
I have seen patients shot in top back part of the head [who've come out with good levels of functioning]. I had one guy, the bullet went through the brain and came out by his eye. That’s a very deadly looking injury, but he was able to talk and walk. A lot of these patients are drug dealers [and we don't know how high a level they were functioning previously]. In this case, I can’t tell what he was like before, but he looked pretty good after. (More on Time.com: Tragedy in Tucson: Details on Giffords’ Brain Injury)
Where have there been the most advances in treating injuries like this
In many patients—whether stroke, spinal cord injury or gunshot wounds— the majority of the injury comes from secondary [causes]. The advances are not really in surgical technique but in the intensive care unit, in critical and post operative care. There are higher levels of physiological monitoring that allow us to to optimize blood pressure and other factors to try to deliver as much blood flow and oxygen to the injury as possible. There is more sophisticated and invasive monitoring so we can carefully adjust in real time [to problems like swelling and increased pressure].
Is she out of the woods in terms of getting through the riskiest period following the injury?
The most dangerous period for her is the next 72 hours, to survive the peak in [brain] pressure. Blood clots, infection and other things can happen that are crucial to determining both survival and how much function there will be. In a way, we can do a lot. But that said, all these measures can only mitigate the damage, we can’t undo it.
We’re just spraying a hose on the fire, but the fire has already been set.