A herniated disc occurs when the soft, gel-like center of a spinal disc pushes through a tear in the tougher outer layer. This displacement can irritate or compress a nearby spinal nerve root. This nerve irritation often results in radicular pain, commonly known as sciatica. The pain involves both mechanical pressure and chemical inflammation caused by materials released from the disc. Steroid injections offer a non-surgical option to manage the intense pain and inflammation associated with this condition.
How Steroids Reduce Pain from Herniation
The discomfort from a herniated disc stems largely from inflammation surrounding the spinal nerve root. The nucleus pulposus, the inner substance of the disc that leaks out, contains inflammatory agents that directly irritate the nerve. These chemical irritants contribute significantly to the pain signals sent to the brain.
Corticosteroids are potent anti-inflammatory drugs similar to the hormone cortisol naturally produced by the body. Once delivered to the affected area, they suppress the body’s inflammatory response. This action decreases swelling and blocks the production of pro-inflammatory chemicals, such as certain cytokines, which are responsible for nerve sensitization. This process calms the hypersensitive nerve and helps alleviate the radiating pain.
The Epidural Injection Process
The treatment involves an Epidural Steroid Injection (ESI), which delivers medication directly into the epidural space of the spine. The epidural space is the area surrounding the spinal cord and nerve roots. This direct delivery method ensures a high concentration of the corticosteroid reaches the inflamed nerve root.
The procedure is performed using imaging guidance, typically fluoroscopy, a type of real-time X-ray. Fluoroscopy allows the physician to visualize the needle’s path and confirm its precise placement within the epidural space. Before the steroid is injected, a contrast dye is administered to verify proper medication flow and ensure the needle is not inadvertently placed in a blood vessel.
There are three common approaches used to access the epidural space, depending on the location of the herniation. The interlaminar approach injects the medication between two vertebrae, while the transforaminal approach targets the opening where the nerve root exits the spine. The caudal approach is performed near the sacral hiatus. The entire injection process usually takes only about 15 to 30 minutes to complete.
Expected Outcomes and Treatment Limits
The primary goal of an ESI is to manage radicular symptoms, providing a window of pain relief that allows the patient to participate in physical therapy. The injection does not physically repair the underlying disc herniation itself. Instead, it temporarily reduces the inflammation, giving the body time to heal and reabsorb the disc material naturally.
Pain relief is not always immediate; the anti-inflammatory effects may take anywhere from one to seven days to become noticeable. The duration of relief is highly variable, typically lasting for several weeks to a few months, though some individuals may experience relief for up to a year. If the initial injection is successful but the pain returns, the procedure can be repeated.
Medical guidelines recommend limiting ESIs to about three or four injections per year. This restriction minimizes cumulative exposure to corticosteroids, which can lead to systemic side effects like weakening of spinal bones or nearby muscles. Patients are considered candidates for an ESI after conservative treatments, such as oral medications and physical therapy, have failed to provide adequate relief.
Safety Considerations and Complications
Epidural steroid injections are considered a safe procedure when performed by a trained specialist using fluoroscopic guidance. Patients may experience common, mild side effects that are temporary and resolve quickly. These can include a temporary increase in pain at the injection site, headache, facial flushing, or a temporary rise in blood sugar levels for people with diabetes.
While rare, more serious complications can occur. Potential severe risks include infection, bleeding that could form a hematoma, or nerve damage. Extremely rare complications, such as stroke, paralysis, or loss of vision, have been reported, primarily linked to inadvertent injection of the steroid into a blood vessel. The use of fluoroscopy and contrast dye helps mitigate these serious risks by confirming proper needle placement and avoiding intravascular injection.