Epidural injections have been used in the management of neck and back pain for almost 100 yr, although they still remain quite controversial. The first reported epidural injection for pain management was in 1901 in Paris. M. A. Sicard injected cocaine for the treatment of sciatica (26). The description of the paramidline approach to the lumbar epidural space was proposed by Pagés in 1921 (27). Pagés' technique used the tactile feedback from the needles touching and passing through the ligamentum flavum as a means of identifying the epidural space. Confirmation of needle placement in the epidural space was based on absence of free flow of spinal fluid from the needle and the lack of resistance to injection of local anesthetic (27). This approach was technically demanding and was associated with a significant failure rate.
The problems inherent in Pagés' technique led to further refinements in the loss of resistance technique.
Forestier and Sicard advocated attaching a fluid-filled syringe to a needle and injecting continuously while advancing the needle through the ligaments of the spine (28). Sicard envisioned that the injectate served as a fluid trocar that atraumatically pushed the dura away from the advancing needle. Using a different approach, injecting through a sacral foramen, Evans reported the use of epi-dural anesthetics and saline for the treatment of sciatica in a 1930 Lancet paper (29).
In 1933, drawing from the work of Sicard and Forestier, Dogliotti introduced the loss of resistance technique into clinical practice (30). Dogliotti's technique relied on the sudden loss of resistance to injection when the needle bevel passed from the dense ligamentum flavum into the fat-containing epidural space. Independently, in the same year, Gutierrez suggested that the negative pressure of the epidural space might be used to identify the epidural space and devised the hanging drop technique (31). This technique involves placing a drop of local anesthetic into the hub of a needle, and the needle is then advanced toward the epidural space. Gutierrez postulated that, as the needle bevel passes through the ligamentum flavum into the negative pressure of the epidural space, the drop of local anesthetic is sucked through the needle into the epidural space (31). Measurements of epidural pressure have caused this mechanism to be called into question (32).
In spite of these technical advances, many considered epidural anesthesia an unreliable anesthetic technique as compared with spinal anesthesia. For this reason, epidural anesthesia remained popular with a limited number of practitioners. Interestingly, it was the development of the Tuohy needle rather than a new drug that renewed interest in epidural anesthesia. The Tuohy needle not only reduced the incidence of inadvertent dural punctures but also allowed the practitioner to maintain analgesia for prolonged periods through the use of indwelling catheters placed through the needle (33). The introduction of lidocaine into clinical practice in the early 1950s added a greater margin of safety for epidural anesthesia and led to increased use of epidural anesthesia in obstetrics. Bupiva-caine, introduced in the early 1960s, enabled physicians to provide long-lasting neural blockade from a single injection and made epidural nerve block an option in a variety of new clinical situations. The first epidural steroid administration was reported in 1952, which was performed through the first sacral foramen (34). The discovery of the clinical utility of epidural steroid administration in the management of radiculopathy and other painful conditions and of opioids in the management of cancer-related pain brought epidural nerve block into the mainstream of pain management (35).
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