Technical advantages of the paramedian approach for lumbar epidural puncture and catheter introduction. A study using epiduroscopy in autopsy subjects.

The lumbar epidural space of 14 autopsy subjects was examined by epiduroscopy. The aim was to compare the midline and paramedian approaches of locating the space, the estimated risk of accidental dural puncture, the course taken by the epidural catheter after introduction and with special attention to the influence of the dorsomedian connective tissue band. The paramedian needle passed a greater distance within the epidural space before contact with the dura mater and demonstrated a low risk of accidental dural puncture. The catheter passed by the paramedian approach did not cause any tenting of the dura and took a straight cephalad direction in all 14 cases. The midline catheter caused tenting of the dura in all 14 cases and the direction of travel was variable. Differences were statistically significant. Influence of the dorsomedian connective tissue band was greatest on the behaviour of the midline needle and catheter.