Spinal and epidural block



What is the difference between spinal and epidural block?

The terms "regional anaesthesia", "spinal block" and "epidural block" are often used interchangeably. This is incorrect. Both spinal and epidural block are subsets of regional anesthetic. 

Spinal block differs from an epidural block in a number of ways.

  • A smaller needle is used to perform a spinal block than an epidural block.

  • The drugs are injected into the cerebrospinal fluid that bathes the spinal cord. In order to do that the needle makes a tiny hole in the dura, which is a tissue encasing the spinal cord and the cerebrospinal fluid. Small doses of local anaesthetic are required because they spread more easily in the spinal fluid. With an epidural block, the drugs are delivered outside the dura, in the epidural space, hence the name for the block. Occasionally, the dura can be inadvertently breached in performing an epidural block, known as a dural puncture. Larger doses of local anaesthetic are required because the spread is through tissues rather than fluid.

  • A spinal block is a single injection of local anaesthetic medications and so there is only one opportunity to deliver the medications. With an epidural, a catheter sits in an epidural space so drugs can be delivered as needed to extend the duration of the block. An epidural block can be made to last longer than a spinal block.

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