Zero gravity may cause a worrying condition in otherwise healthy astronauts.
Researchers theorize zero gravity is causing increased skull pressure, which is the main culprit in a condition called papilledema, a swollen optic nerve that can lead to vision loss. Now, a University of Minnesota researcher is pioneering a technique that could help NASA and others detect the condition.
So far, 17 American astronauts have contracted papilledema. In outer space, there is no way to test astronauts for high skull pressure, leading to a conundrum for the National Space Biomedical Research Institute, a NASA-partnered research center.
Looking for answers, the NSBRI turned to University of Minnesota researcher Uzma Samadani, to find new ways to measure skull pressure in space.
“When you go up into space, everything shifts because of the lack of gravity… and so there is a bit of a change in how fluids are distributed,” said Dorit Donoviel, deputy chief scientist of NSBRI.
Samadani, an associate professor in the Department of Neurosurgery, and her team wrote a paper illustrating the use of eye tracking technology to show if someone’s skull pressure is elevated.
The research, funded by NSBRI and published online June 2 in the Journal of Neurosurgery, involves a person watching a small moving video, like a music video or movie clip, as an observer tracks how their eye moves.
“You have three nerves that move your pupils and we can tell if one of them is impaired because it will show particular metrics that are off,” Samadani said.
This condition sometimes persists once astronauts return to Earth and appears to get worse the longer astronauts stay in zero gravity, she said.
The most common method of detecting elevated intracranial pressure, or high skull pressure, is unfeasible in space.
Typically, a doctor would drill a hole in someone’s head or spine to check pressure, said Cornelius Lam, professor in the Department of Neurosurgery.
Back on Earth, trauma, strokes and tumors are all common causes of elevated ICP, Samadani said.
“The space program has been looking for noninvasive and simple ways to assess whether pressure on the brain is elevated,” Donoviel said.
Samadani’s technology is attractive for its simplicity, and astronauts can use it on their own, Donoviel said. Still, the method lacks the ability to measure brain pressure numerically.
“The very simple, easy to use technology is something that could be very easily implemented in the international space station, or even on the way to Mars,” she said.
Along with Samadani’s research, Donoviel also presented several other researchers’ ideas to NASA for consideration.
It is likely that NASA will pick two or three different technologies to send into space, Donoviel said.
Diagnosing the issue is just step one of a more complex problem for astronauts, she said. Medication is the go-to treatment for elevated ICP on Earth, but space complicates that.
“Astronauts have so many changes going on in their bodies, we’re very reluctant to give them medications,” Donoviel said.
The eye tracking method is currently awaiting FDA approval, Samadani said.
Back on Earth, the method may have other applications. It could enable quick diagnoses in an emergency room, or help assess treatments of other skull pressure related conditions.
She has already used this technology on other brain injuries, like concussions, but this is the first time it has been used to find high skull and brain pressure.
“If you have [elevated ICP] for a long time, it can impact cognition, so it slows down your thinking, it can cause headaches … and you can actually even go blind from it,” Samadani said. Untreated, high ICP can even kill.
