Space travel can impair eyesight and change pituitary shape finds MRI study

Researchers have been exploring how spaceflight can affect human physiology and human health for a long time . The earlier studies revealed several facets of the issue and uncovered a multitude of ways that space changes our bodies — even our gene expression.

US researchers have found in a new study with help of series of magnetic resonance imaging scans (MRI scans) that spaceflight could affect the human brain in strange and unusual ways including long-lasting changes in the brain's white matter volume and the shape of the pituitary gland . The findings of the study have been published in the journal Radiology.

The findings may have health implications like impairment of astronaut eyesight and last for a long time. The examination of patients with "spaceflight associated neuro-ocular syndrome" has revealed a number of structural changes, including swelling of the optic nerve and retinal haemorrhage.

This is probably why after expeditions to the International Space Station, more than half of astronauts reported experiencing changes in their vision – most commonly in the form of farsightedness and resultant headache. However in severe cases the eye changes manifested as a loss in both near and distant acuity.

The researchers conducted a series of brain magnetic resonance imaging scans (MRI scans) on 11 astronauts – 10 men and one woman – prior to and after missions to the International Space Station. They found that significant time spent in the orbiting laboratory's microgravity environment caused the crew's brain and cerebrospinal fluid volumes to expand – an effect that was found to persist at least a year later.

The researchers reported that prolonged microgravity exposure caused the following brain changes:

(1) an approximate 2% expansion of brain and cerebral spinal fluid (CSF) volumes, attributable to both white matter and lateral ventricular measurements, and these remained elevated at 1-year after spaceflight, suggesting permanent alterations;

(2) a 13% increase in mean CSF intraventricular (aqueductal) flow velocity, suggesting a reduction in intracranial compliance; and

(3) in roughly half (six of 11 astronauts), depression of the pituitary dome compared with baseline (average midline height decreased from 5.9 to 5.3 mm), suggesting elevated intracranial pressure during spaceflight.

The researchers also observed changes in the shape of the pituitary gland in many of the test subjects following their spaceflights – with the gland becoming smaller and flatter.

The researchers concluded that long-duration spaceflight was associated with increased pituitary deformation, augmented aqueductal cerebrospinal fluid (CSF) hydrodynamics, and expansion of summated brain and CSF volumes. Summated brain and CSF volumetric expansion persisted up to 1 year into recovery, suggesting permanent alteration.

For further reference log on to:

https://doi.org/10.1148/radiol.2020191413