An epidural is a spinal procedure that delivers anesthetic or painkilling drugs to the nerves that convey pain.
It is often used while women are in labor to ease the pain of childbirth. It is also commonly used to numb women while they have a Caesarean section.
The name ‘epidural’ comes from its place of delivery into the body, the spine. The spinal cord is surrounded by cerebrospinal fluid which helps protect and cushion the brain and spinal cord from damage. The fluid is held within a tough sheath called the dura, which means ‘hard’ or ‘tough’. However, the spinal cord and the dura do not run all the way down the entire length of the spinal canal: they come to an end at the first lumbar vertebra (one of the bones of the back).
An epidural is delivered to the area of the spinal canal that is not protected by the dura, known as the epidural space. This space contains the spinal nerves which then pass up the spinal cord to the brain. Epidural literally means ‘above the dura’, so some doctors prefer to call it an ‘extradural’ or ‘peridural’ which mean ‘outside the dura’.
A skilled anesthetists can control the amount of pain relief or numbness you receive, while still allowing you to retain some sensation and some movement.
This is because the nerve fibers that transmit pain are relatively thin, compared with the nerve fibers that allow movement of the skeletal muscles or the sensation of touch, which means the ‘pain’ nerve fibers are affected by the anesthetic more quickly. In addition, the anesthetists can adjust the strength of the anesthetic to offer a fine balance between pain relief and the ability to move.