The Difference between an Epidural and a Spinal Block

Spinal and epidural anesthesiaare regional anesthetic techniques that target the lower half of the body. So called neuraxial blocks, these techniques involve the injection of an anesthetic medication directly into or around the spinal area. A local anesthetic is usually used around the area of injection prior to the procedure.

Recommendation for a spinal or epidural anesthesia depends on the type of surgery the patient will undergo. They are often used for childbirth as well as surgeries that involve the pelvis, hips and legs. Moreover, studies suggest that spinal or epidural anesthesia have fewer side effects and risks as compared to general anesthesia. These procedures were observed to result in less blood loss and better pain management after surgery resulting in faster recovery of patients.

Although spinal and epidural anesthesia appear similar, they are actually two different methods. Their main differences include the procedure, dosage used, and onset of the anesthetic effect among others.

Both spinal and epidural shots most commonly go in the lower back. The spinal technique is restricted to the lumbar area, below the L2 to avoid damaging the spinal cord. The medicine is injected directly into the fluid in the spinal cord. Usually, only a single-shot injection of the spinal anesthetic is given. In some cases, especially in pain management, spinal anesthetics may be administered continuously with an infusion pump or by giving boluses through a spinal catheter. The anesthetic takes effect right away and is preferred for short and simple procedures.

The epidural anesthesia, although most commonly injected in the lower back, may also be administered in the mid-back area or the thoracic region or virtually any level of the spine. This versatility allows the epidural technique to be more flexible and useful in clinical practice. The epidural technique involves the injection of anesthesia to a region called the epidural space. Upon verification of the position, a small catheter is placed through which local anesthetics may be given as needed throughout the duration of the procedure. The medicine takes effect approximately 10-20 minutes after injection. Because the involved space for an epidural anesthesia is larger compared to spinal, the dose required is usually larger.  

With the epidural technique, segmental anesthesia is possible. This cannot be created with the spinal technique as the block will involve all segments. Further differences include the factors that affect the extension of the block. With the epidural technique, the posture of the patient is not as important as in the spinal technique. The epidural technique is dependent on the volume and rate of injection while the spinal technique is dependent on the density of the solution and position of the patient.

Both procedures are generally safe and pose lesser risks compared to general anesthesia. Possible complications that may occur include an allergic reaction to the anesthetic used, hematoma or bleeding around the spinal column, difficulty in urinating, drop in blood pressure, spinal infections (meningitis or abscess), nerve damage, severe headaches, or, in very rare cases, seizures.

All clinical procedures, including anesthetic techniques, should be well analyzed and should therefore be discussed with your doctor. Benefits and risks should always be weighed to be able to determine which procedure is best.