"It always makes people who do what I do nervous when you hear someone say that someone has a 101 percent chance of surviving," Dr. David Okonkwo, director of the Brain Trauma Research Center at the University of Pittsburgh, told AOL News today in a phone interview. "The reality is that patients who sustain gunshot wounds to the head are at risk for a litany of downstream, secondary complications that can impede their recovery and at times can be dangerous."
Doctors at the Houston hospital treating Giffords said she is improving today after receiving a tube to drain excess cerebrospinal fluid on Saturday but will likely remain in the intensive care unit of Texas Medical Center until the end of this week, delaying her move to a nearby rehabilitation center.
The news didn't cause alarm among neurosurgeons, who explained that patients with gunshot wounds to the head often develop hydrocephalus, or an extra fluid buildup around the brain. Healthy people also create cerebrospinal fluid -- about a soda-can's worth each day -- but their bodies are able to drain the liquid.
For about one out of every three people who has been shot in the head, however, the fluid builds up, creating pressure on the brain, and has to be drained with a temporary tube or a permanent shunt. Giffords' medical team at the University Medical Center in Tucson first noticed the fluid on Tuesday, and doctors in Houston say they are continuing to monitor the condition.
"Water on the brain is not unusual after a brain injury. It's a known, common occurrence; it's something we look for, and it's only a minor setback," said Dr. M. Sean Grady, chairman of the Department of Neurosurgery at the University of Pennsylvania School of Medicine.
If the fluid continues to build up around Giffords' brain, neurosurgeons say, her doctors may choose to implant a permanent shunt.
"It's a simple procedure," said Dr. Henry Brem, the chief of neurosurgery at Johns Hopkins Medical Center in Baltimore. "The only major concern would be infection," he told AOL News by phone today. He said the surgery itself usually sets patients back only a day or two.
A bullet went through the left side of Giffords' brain when she was shot Jan. 8 during a political meet-and-greet in a supermarket parking lot in Tucson. Six people died, and several others were wounded. Doctors have said they are very pleased by the rapid progress Giffords is making. The fluid buildup was the only setback they have reported so far.
But other concerns remain. Survivors of traumatic brain injury are often at an increased risk for other conditions for the rest of their lives, from epilepsy to brain infections.
The risk of meningitis is also increased. So far, though, Okonkwo said Giffords' progress is remarkable.
"She got shot in the head and she's alive. The most likely scenario is that she sustains a functional recovery, but that doesn't necessarily mean she returns to Congress," he said.
"Only time will tell. I have some patients who go through something like this and you would never know it, but for others, gunshot wounds to the head turn into a kind of chronic disease."