Dural puncture with a 26-gauge spinal needle affects spread of epidural anesthesia

Combined spinal and epidural anesthesia may increase the risk of epidurally administered drugs spreading into the subarachnoid space through the dural hole. We studied the effect of dural puncture with a 26-gauge needle on the spread of analgesia induced by epidural injection of local anesthetics. Forty patients were randomly assigned to control and dural puncture groups. In the dural puncture group, the dura was punctured with a 26-gauge Whitacre spinal needle at L2-3 but no drug was injected. In both groups, an 18-gauge epidural catheter was inserted 4 cm cephalad into the epidural space at L2-3 and 15 mL of 2% mepivacaine without epinephrine was injected. Analgesia was assessed by pinprick at 5, 10, 15, and 20 min after injection and at the end of surgery. The caudal spread of analgesia was significantly greater in the dural puncture group than in the control group 15 and 20 min after injection (P < 0.01), but the cranial spread of analgesia was not different between the two groups. We conclude that dural puncture (without drugs) using a 26-gauge Whitacre spinal needle before epidural injection increases caudal spread of analgesia induced by epidural local anesthetics.