epidural
Meaning of epidural: A catheter left sitting in the space outside the cord is what lets the block be topped up, adjusted or deepened.
Definition of epidural
Epidural means relating to the epidural space, the narrow gap between the bony wall of the spinal canal and the dura mater, the tough membrane wrapping the spinal cord. The space holds fat and veins and runs the length of the spine. Used on its own, the word usually means an epidural injection or infusion given to block pain.
How does an epidural differ from a spinal?
Both place medicine in the lower back, and the difference is a matter of millimeters. An epidural stops outside the dura, while a spinal anesthetic passes through it into the cerebrospinal fluid bathing the cord directly.
| Feature | Epidural | Spinal |
|---|---|---|
| Where the drug goes | Fat filled space outside the dura | Fluid surrounding the spinal cord |
| Dose needed | Larger, since it must spread and diffuse | Much smaller |
| Onset | Gradual, over a stretch of minutes | Rapid |
| Duration | Extended for as long as the catheter is topped up | Usually limited to one dose |
Choice follows the operation. A short procedure suits the quick, dense block of a spinal, while labor or a long abdominal case suits a catheter that can be adjusted over hours. The two are sometimes combined, a spinal for speed with a catheter left in place for whatever follows.
Why is a catheter left in place?
A single injection wears off on a schedule nobody controls. A fine tube threaded into the space and taped up the back allows the dose to be repeated or run continuously, raised when pain breaks through and lowered when the block spreads further than intended. That adjustability is the main practical advantage of the route, and it also allows the block to be deepened if labor ends in an operation, without starting again. The same route carries recognized drawbacks: a patchy or one sided block, a fall in blood pressure as vessels relax, and heaviness in the legs that varies with the drug and the dose.
What else does the word describe?
The epidural space is not only an anesthetic target. Steroid mixed with local anesthetic is injected there to settle nerve root pain from a slipped disk. A small volume of a person's own blood is placed there to seal a leak of spinal fluid after a puncture headache. Disease reaches the space too. A tumor deposit growing within it can press on the spinal cord, which is treated urgently because compression damages the cord quickly, and infection there forms an epidural abscess. Inside the skull the same word names the space between bone and dura, where a torn artery after a head injury produces an epidural hematoma.
Used in a sentence
An epidural catheter was placed to provide continuous pain relief during labor.
Good to know
An epidural is delivered into the space outside the covering of the spinal cord, while a spinal injection enters the fluid surrounding the cord directly, a distinction that affects both onset and duration of the effect.
Word origin
Where “epidural” comes from
Formed from epi-, Greek for upon or above, and dura, from Latin durus, meaning hard, referring to the tough membrane covering the spinal cord.