What is an epidural steroid injection?
An epidural steroid injection is a common procedure to treat spinal nerve irritation that is most often caused by tissues next to the nerve pressing against it. The beginning of the nerve (nerve root) may be irritated by a bulging intervertebral disc, disc contents ("ruptured disc") or bone spur, directly touching the spinal nerve.
Picture of a disc herniation compressing the spinal nerve root
An epidural steroid injection involves bathing an inflamed nerve root in steroids (potent anti-inflammation medicine) in order to decrease the irritation of the nerve root that is causing pain.
How is an epidural steroid injection performed?
The epidural steroid injection procedure is quick and simple. While it is common for people to be concerned prior to the procedure, it is actually frequent to hear from patients afterwards: "Is that all?"
The spinal cord rests in the spinal canal. The nerve roots branch out from the spinal cord at each level of a spinal vertebra (the bony building blocks of the spine). The cord is protected by cerebrospinal fluid (CSF), which serves as a shock absorber for the cord. The CSF is held in place by a membrane with several layers, one of which is called the dura, from the Greek for tough (think of "durable"). The Greek word "epi" means "outside of." So, the epidural space is outside of this tough membrane. During an epidural steroid injection, a needle and syringe are used to enter the epidural space and deposit small amounts of long-lasting steroids around the inflamed spinal nerve. A fluoroscope (a viewing instrument using X-rays) is used to visualize the local anatomy during the injection. The epidural steroid injection specifically targets the locally inflamed area and treats it with a maximal amount of steroids, thereby minimizing exposure of the rest of the body to the steroids.
Epidural steroid injection with injection needle visible in the epidural space using a fluoroscope
When are epidural steroid injections used?
Epidural steroid injections are most commonly used in situations of radicular pain, which is a radiating pain that is transmitted away from the spine by an irritated spinal nerve. Irritation of a spinal nerve in the low back (lumbar radiculopathy) causes pain that goes down the leg. Epidural injections are also used to treat nerve compression in the neck (cervical spine), referred to as cervical radiculopathy, which causes pain.