Recent studies using magnetic resonance imaging (MRI) have suggested cerebrospinal fluid (CSF) motion caused by respiration to play a more important role than previously thought. The cardiac cycle of CSF motion is used clinically, often to predict which hydrocephalus patients will respond to shunting and who will not.

This talk asks the question whether CSF flow could also be regulated by the longer respiratory cycle. To assess this question we applied in vivo pressure measurements to a simplification of the spinal canal and the aqueduct. From this we can measure the amplitude of the flow components induced by the cardiac and respiratory cycle respectively.

In our study the amplitude of CSF motion was higher for respiration in the spinal canal, and in the aqueduct cardiac the two amplitudes were approximately equal.

This is a starting work, so no conclusions can be made yet. We emphasize the point that it is possible for small and long pressure waves in respiration to cause greater flow than a short cardiac pressure wave with a greater amplitude.