Fig. 2. Three types of the cerebrospinal fluid velocity (CSFV) waveforms before (  open circles ) and after epidural saline injection (  closed circles ). (  A : saw type) CSFV profiles in a 45-yr-old man whose cerebrospinal fluid volume decreased from 43.3 ml to 39.3 ml after injection of 10 ml saline. Although there was a smooth waveform, which synchronized with the cardiac cycle, in the CSFV profile before saline injection, the waveform became sawlike after epidural saline injection. (  B : decrease type) CSFV profiles in a 31-yr-old man whose cerebrospinal fluid volume decreased from 35.7 ml to 23.1 ml after injection of 15 ml saline. After epidural saline injection, the synchronized waveform was maintained and peak systolic (CSFV^systolic) was decreased. (  C : increase type) CSFV profiles in a 19-yr-old man whose cerebrospinal fluid volume decreased from 28.6 ml to 26.0 ml after injection of 5 ml saline. After epidural saline injection, the synchronized waveform was maintained and CSFV^systolicwas increased.