Intracranial pressure in microgravity conditions: non-invasive assessment by ophthalmodynamometry

Background: As well known from former manned spaceflight experiments (German D2-Mission/German D1-Mission 1985/German-Russian MIR-Mission 1992/German-D2-Mission 1993), fluid shift after entry into microgravity leads to a rapid increase in pressure and volume within the upper compartments of the human body. This has been proven by precise measurements with automatic selftonometers for intraocular pressure. Hypothesis: There is little doubt, that a very similar-even more, marked-increase of intracranial pressure happens soon after entry into microgravity. This may be the cause for some of the reported hormonal and even neurological changes in metabolism. There is no non-invasive method to assess these important increases in pressure. Methods: Ophthalmodynamometry in general allows for rather precise estimation of intracranial BP, but so far the method was too complicated for routine application, specifically in spaceflight conditions. Therefore, using the microprocessor controlled technology of our automatic selftonometer we have designed a very precise automatic instrument which can be applied by the astronaut/kosmonaut. The measurement takes only a few seconds. Conclusions This easily applied, non-invasive method would allow for completely new insights into these important changes and explain some of the clinical consequences noted so far.