[Flow kinetics of the endolymph in caloric stimulation]

From our experiment in fluid mechanics there is strong evidence that caloric nystagmus is caused by streaming endolymph in weightlessness as well as by gravity. Two different mechanisms are postulated: thermoconvection (dependent on gravity and head position) and thermo-induced change in volume (independent of those two factors). Our results indicate that tangential endolymph flow in the ampulla directed from crista to cupula leads to a nystagmus towards the examined ear, whereas the adverse flow leads to a nystagmus to the other side. Depending on the head position the flow due to thermoconvection is increased or decreased by the flow due to extension. In mathematical approaches we found the flow due to the thermoconvection to be somewhat higher than that due to fluid extension, but still in the range of micron/s.