Astronaut Risks During Life In Space

Ilustrasi Astronaut (Image by WikiImages from Pixabay)

JAKARTA - Living in outer space is not without risks. It has long been known that this often causes vision problems in astronauts and has other implications for their health, including changes in brain volume.

A new study in the journal Radiology quoted from CNN International shows that the impact of long-term space travel over a longer distance, has the potential to cause changes in brain volume and deformation of the pituitary gland.

More than half of the crew members on the International Space Station (ISS) have reported changes in their vision after long-term exposure to microgravity. Research on astronauts after a space mission (postflight) has revealed swelling of the optic nerve, bleeding in the retina and other ocular structural changes.

Scientists have hypothesized that chronic exposure to increased intracranial pressure, or pressure inside the head, during spaceflight is a contributing factor to these changes. When on Earth, the gravitational field creates a hydrostatic gradient, the pressure of liquid that increases from head to foot when standing or sitting. This pressure gradient does not exist in space.

"When you are under microgravity, fluid such as your venous blood no longer enters your lower limb but redistributes it forward. The movement of fluid to your head may be one of the mechanisms that causes the changes we observe in the eye and intracranial compartment," said study lead author Larry A. Kramer, MD, of the University of Texas Health Science Center in Houston.

To find out more, Kramer and several colleagues performed brain MRIs on 11 astronauts, including 10 men and one woman, before they traveled to the ISS. The researchers continued with the MRI study a day after the astronauts returned from their 171-day stay in space.

The results of this study suggest that long-term microgravity exposure causes expansion in the astronaut's combined brain and cerebrospinal fluid volume (CSF). CSF is a fluid that flows in and around the hollow spaces of the brain and spinal cord. The combined volume remains high even though it has passed one year's postflight, of course this shows a permanent change.

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The researchers also observed an increase in brain changes as astronauts underwent postflight, averaging in the ventrical system of the brain that contains CSF. The changes are similar to those of people who have spent long periods of rest with their head tilted slightly downward, in a research study that simulated shifting of fluid toward the head in microgravity.

In addition, there is an increase in the velocity of CSF flow through the brain drains, the narrow channels that connect the ventricles in the brain. A similar phenomenon has been seen with hydrocephalus disease, a condition in which the ventricles in the brain enlarge abnormally.

Symptoms of the condition include difficulty walking, problems with bladder control and dementia, which is a change in how you think and interact with other people. Often, short term memory, thoughts, speech and motor skills are affected. To date, these symptoms have not been reported to astronauts after space travel.