Epidural space and regional anesthesia

Epidural fat provides sufficient cushion for the pulsatile movements of the dural sac, protects nerve structures, facilitates the movement of the dural sac over the periosteum of the spinal column during flexion and extension, and forms a pharmacologic reservoir of lipophilic substances. Root cuffs have a cellular component that affects the passage of substances injected epiduraly or near the intervertebral foramen, depending on the site of injection, preganglionar, postganglionar or ganglionar. We found fat inside root cuffs but not within the dural sac. Fat in this location may have affect kinetics of lipophilic drugs injected near nerve root cuffs. Ultrastructural morphology of the cellular component at preganglionar level may help explain unexpected subdural blockade after injection of local anesthetic via transforaminal route. Other morphological aspects of nerve root cuffs help to understand the function of the blood-nerve barrier.

Based in this anatomical knowledge, we can speculate on the possible anesthetic implications of epidural fat in terms of the pharmacokinetics of drugs injected into the epidural space and the tasks of locating the epidural space and inserting an epidural catheter during anesthetic procedures.