What is the difference between an epidural and spinal block?

Both epidural and spinal nerve blocks involve the placement of a needle into your lower back. For epidurals, a small plastic tube (catheter) is threaded through the needle before the needle is withdrawn. Medications (local anesthetics and/or narcotics) are then injected via the spinal needle or epidural catheter.

Epidural analgesia or anesthesia involves the injection of medication into the “epidural space.” Because the medication needs to cross the membrane (dura mater) surrounding the spinal cord before reaching the targeted nerves, it usually takes approximately 10-15 minutes for pain relief to occur. The placement of a catheter during insertion makes possible the continuous infusion of pain medications for the duration of your labor and for the addition of stronger medications if necessary.

Spinal analgesia or anesthesia involves the injection of medication into the fluid (cerebrospinal fluid, or CSF) that bathes the spinal cord. Spinal needles are much thinner than epidural needles and spinal doses are smaller than epidural doses. However, the duration of pain relief is finite (about 1-2 hours) because there is no catheter and therefore, no continuous infusion.