Abstract
In the present review, the author described some important information regarding epidural, spinal, or combined spinal and epidural anesthesia (CSEA). The author has demonstrated that the cephalad spread of the contrast medium in the subarachnoid space, and the compression of the subarachnoid space are observed after epidural injection of physiological saline solution using myelography and magnetic resonance imaging (MRI). These studies suggest the volume effect during CSEA. Furthermore, the author reported that the cauda equina moved to the gravity-dependent side, when changing from the supine to the lateral decubitus or prone position. These results differ from the previous studies, so that it is necessary for us to guard against movement of the cauda equina when we perform the spinal anesthesia.
