The epidural is a form of regional anesthesia that delivers pain-relieving medication directly into the space surrounding the spinal nerves. This technique is widely recognized and frequently used for pain management during surgical procedures and, most commonly, for relief during labor and delivery. The procedure involves inserting a thin catheter into the epidural space, which is the outermost area of the spinal canal. The history of the modern epidural is rooted in the late 19th century pursuit of localized pain control.
Precursors to Regional Anesthesia
The foundation for epidural anesthesia was laid with the discovery of local anesthetics in the mid-19th century. German chemist Friedrich Gaedcke isolated cocaine from the coca leaf in 1855, and Austrian ophthalmologist Karl Koller demonstrated its clinical application in 1884 by numbing the surface of the eye. This success quickly led to the exploration of using these agents to block nerves deeper within the body.
In 1885, American neurologist James Leonard Corning experimented with injecting cocaine between the vertebrae of a dog and then a patient. Corning’s technique did not result in cerebrospinal fluid flow, which suggests his injection likely landed in the epidural space, making it an accidental precursor to the epidural technique.
The focus of regional anesthesia then shifted to the subarachnoid space, which contains the cerebrospinal fluid. German surgeon August Bier performed the first intentional spinal anesthesia in 1898, injecting cocaine directly into this space. Bier’s work proved that targeted pain relief could be achieved by accessing the central nervous system, setting the stage for the formal identification of the epidural space.
The Initial Invention and Definition
The invention of the epidural technique is generally credited to two French physicians working independently around 1901. Neurologist Jean-Anthanase Sicard and surgeon Fernand Cathelin both described the use of a caudal approach to inject an anesthetic solution into the epidural space. This caudal approach involves placing the needle near the sacrum, at the very base of the spine. Their initial applications were for treating conditions like sciatica and for surgical procedures on the lower abdomen and urinary tract, not for labor pain.
The epidural space, also known as the peridural or extradural space, is located outside the dura mater, the tough membrane surrounding the spinal cord. This technique differed fundamentally from spinal anesthesia, which targets the subarachnoid space.
A significant refinement came in 1921 when Spanish military surgeon Fidel Pagés Miravé published his successful use of the lumbar approach. This technique involves needle placement in the lower back, a more direct route to the area innervating the lower body. The distinction between spinal and epidural techniques was further solidified by the development of methods to reliably identify the epidural space, including the “loss of resistance” technique described by Achille Mario Dogliotti and Alberto Gutierrez in the 1930s.
Adaptation for Labor and Delivery
Despite these early successes, the epidural remained a single-injection technique, limiting its use primarily to short surgical procedures. The method was not yet practical for the prolonged and variable nature of labor pain, though early attempts were made by Romanian obstetrician Eugene Aburel in 1931 using a silk catheter.
The major breakthrough that allowed the epidural to become the standard for obstetric analgesia occurred in the late 1940s. In 1949, Cuban anesthesiologist Manuel Martinez Curbelo reported the first successful use of continuous lumbar epidural anesthesia.
He employed a Tuohy needle and a catheter that remained in the epidural space, allowing for repeated or continuous dosing of the anesthetic. This innovation transformed the epidural from a single-shot procedure into a flexible, continuous method of sustained, adjustable pain relief, making it the preferred technique for childbirth.
Modern Epidural Techniques
The evolution of the epidural continues today, focusing on maximizing patient comfort and minimizing side effects. A major advancement is the shift to using highly dilute concentrations of local anesthetics, often mixed with small amounts of opioids like fentanyl. This combination provides excellent pain relief while reducing the motor block, allowing many patients to retain the ability to move their legs, leading to the term “walking epidural.”
The introduction of Patient-Controlled Epidural Analgesia (PCEA) has given patients greater control over their pain experience. With PCEA, a programmable pump allows the patient to self-administer a small, predetermined dose of medication when needed, ensuring a more consistent level of analgesia.
A further refinement is the Combined Spinal-Epidural (CSE) technique, often called a “needle-through-needle” method. This involves performing a spinal injection for rapid, immediate pain relief, followed by the placement of an epidural catheter for long-term maintenance.