The nervous system is basically a communication network that transfers information to and from the brain. The information pathways go from the brain down the spinal cord, from which the nerves exit. Each spinal bone, or vertebra, has a name that references which part of the spine (cervical, or neck, of which there are 7; thoracic, or upper back, of which there are 12; lumbar, or lower back, of which there are 5; and sacral, in the pelvic region, of which there are 5). The nerves that exit from the spine are named for the vertebral interspace at their point of exit, usually referred to by letters and numbers, e.g., L23 for the space between the second and third lumber vertebra. Each supplies an area of the body known as a dermatome; the dermatomes for each nerve root have been mapped out for the human body and your anesthesiologist is familiar with them.

Epidural anesthesia is achieved by injecting medications into a space within the spine (the epidural space) so as to target those nerves that supply the part of the body for which anesthesia is desired. The actual interspace chosen by your anesthesiologist will be based upon many considerations such as technical and anatomical factors. The epidural space is usually located using a technique that involves finding it with specially designed needles that are inserted after first numbing the skin with a local anesthetic. While epidural anesthesia is sometimes administered as a single injection through that needle, more often a small, flexible, plastic tube known as an epidural catheter is threaded through the needle into the epidural space and is used to administer further doses of medication. In this way the effects of the anesthetic can be continued for prolonged periods of time.

Epidural anesthesia is widely used in modern anesthesia practice. In our practice it is most often chosen for obstetrical anesthesia, major orthopedic surgery, and for post-operative pain control following joint replacement, thoracic surgery, and major abdominal surgery.