Epidural

Question:
What is an epidural?

Answer:
An epidural is a procedure done to either provide a painless state in order to perform surgery and to have childbirth without significant pain, or is used for the diagnosis & treatment of certain chronic pain conditions.

Anatomy: there is a potential space (epi- or extra-dural) located outside the dura which is a thick membrane surrounding the spinal cord and its terminal nerve structures that are called cauda equina. The spinal cord and all these nerve structures are bathed in a watery fluid medium called cerebrospinal fluid which provides the central nervous system with protection, pressure balance, suspension and nutrition. The spinal fluid is contained in between an internal membrane called pia mater and two external coverings (membranes), the first of which is called arachnoid mater and the second and outermost layer is called dura mater.

Just outside the dura mater there is a narrow space containing veins, fat, lymphatics, and through which the nerves travel on their way exiting the spinal canal towards their target sites in the body. This narrow space is termed Epidural Space, and is surrounded on the outside with strong ligaments, periosteum (a strong layer of tissue on the surface of bone) and bony structures that form the spine.

When a person receives an "epidural" it implies the placement of a needle into that space (epidural space), and through that needle a catheter is introduced into the epidural space, then the needle is removed and the catheter is secured in place so that medications can be delivered over extended periods of time. For other specific indications, the medications can be injected directly through the needle as a "one shot" technique, and the needle is then removed.


To be continued....