Figure 6. Visual analog scale (VAS) pain scores (centimeters) in the foot (top) or the hand (bottom) versus clonidine concentration in the current study (squares) and in a previous study [10]after bolus epidural clonidine injection (circles). Regression lines for the current infusion study (solid line) and the previous bolus study (dotted line) reveal no difference between these methods of administration for analgesia in the foot, but more analgesia in the hand at the end of the end of each hour of infusion than after a single bolus injection. CSF = cerebrospinal fluid.