Graph showing distance (mm) CSF in the pre-pontine cistern moved with breath holding. Each of the 10 volunteers was imaged on 3 occasions. Each point on the graph shows the average maximum cephalad and caudad distance with standard deviation that CSF moved in the pre-pontine subarachnoid space during one cardiac cycle and is thought to reflect the systolic and diastolic components of the cardiac cycle. For the group as a whole, CSF in the pre-pontine subarachnoid space moved cephalad 3.0 ± 0.4 mm and caudad 3.0 ± 0.5 mm. CSF movement during breath holding.