Astronauts’ vision sometimes suffers when in space, and it is thought that this is caused by increased brain pressure, which presses onto the back of the eye. A NASA experiment is looking at how fluid shifting in the body might cause this – but a key challenge is actually measuring the brain pressure in space. A pioneering British company has developed a unique device to address this, which could also have many uses on Earth, for example in emergency or intensive care situations.
One of the risks of spaceflight is that, in weightlessness, fluid in the body shifts, mostly in a head-ward direction. This can increase brain pressure, which may in turn push on the back of the eye, affecting astronauts’ vision. Many astronauts have complained of temporary problems with their eyesight, but how and why this happens is not very well understood. A NASA experiment called Fluid Shifts is looking at the underlying physiology, monitoring the changes in astronauts’ bodies and testing ways to counteract them.
One of the most important signs to measure is the change in brain pressure – but monitoring this is a challenging task in space. A British company, Marchbanks Measurements Systems (MMS) Ltd, has pioneered a unique solution: a simple, non-invasive device which is placed in the ear.
Research at University Hospital Southampton NHS Foundation Trust shows that there is an open fluid link between the brain and ear. Brain pressure changes are transferred to the inner ear and are measured in term of tympanic membrane displacement (TMD) by the MMS Cerebral and Cochlear Fluid Pressure (CCFP) Analyser. Both baseline pressure shifts and pressure waves can be measured. The baseline pressure is a surrogate for lumbar puncture (sometimes called a ‘spinal tap’), and it is thought that the brain pressure waves provide a ‘signature’ to underlying disorders. This will be a crucial part of the Fluid Shifts investigation.
Marchbanks Measurement Systems from Southampton is headed by Dr Robert Marchbanks. He and his team have developed a method which uses slight changes in the inner ear to assess brain pressure. This is not only useful for monitoring astronaut health, but could have widespread application on the ground. For example, in emergency situations, being able to quickly and accurately measure a patient’s brain pressure leads to speedier treatment – crucial in determining a their medical outcomes.