Epidural Steroid Injection (ESI)

What It Is

An epidural steroid injection (ESI) is an image-guided injection of a corticosteroid (anti-inflammatory) into the epidural space — the layer of fatty tissue just outside the spinal cord and nerve roots. The medicine bathes the inflamed nerve root and quiets the inflammation that’s producing pain, numbness, or tingling that radiates down an arm or leg.

ESIs are most commonly used in the lumbar spine (low back, sciatica, lumbar disc herniation, lumbar stenosis) and cervical spine (neck and arm radiculopathy from a herniated cervical disc). They are placed under live X-ray (fluoroscopy) for accuracy and are typically delivered through one of three approaches: transforaminal (through the bony opening where the nerve exits), interlaminar (between two adjacent vertebrae), or caudal (through the small opening at the base of the sacrum).

How It Works

The corticosteroid is a strong anti-inflammatory. When placed directly next to an inflamed, compressed nerve root, it calms the swelling and chemical irritation that are amplifying the pain signal. The numbing medicine that’s usually mixed in gives short-term relief and helps confirm the right level was treated.

An ESI does not unherniate a disc, regrow a worn-out joint, or fix the underlying anatomy. It buys a window of relief that lets physical therapy work, lets the natural inflammatory response settle, and in many cases is enough to avoid surgery entirely.

When It’s Used

An ESI is typically considered when:

• Radiating leg or arm pain (radiculopathy) hasn’t settled after a structured trial of physical therapy, NSAIDs, activity modification, and time
• Imaging confirms the symptom pattern matches a specific compressed nerve root
• Surgery is being considered and the patient and surgeon want to try one more conservative step first
• Pain is severe enough to limit function or sleep and a faster reduction is needed

For mechanical low back pain alone, without a radicular component, ESIs are generally less effective and aren’t the first choice.

What to Expect

• The procedure takes about 15 to 30 minutes in a procedure suite at the pain management office or surgery center
• You lie face-down on a fluoroscopy table; the skin is cleaned and numbed with local anesthetic
• The interventional pain physician advances the needle under live X-ray guidance, confirms position with a small amount of contrast dye, then injects the steroid and numbing medicine
• Most patients drive themselves home unless sedation was used
• Relief usually starts 2 to 7 days after the injection and can last weeks to several months
• The same level can be repeated, typically with a minimum interval between injections

Risks and Limitations

• Temporary effect. An ESI calms inflammation; it doesn’t cure the underlying disc, stenosis, or nerve compression.
• Steroid flare. A small group of patients gets a brief increase in pain in the first 24 to 48 hours.
• Blood sugar. If you have diabetes, expect a short rise in blood sugar after the shot.
• Bleeding / bruising. More relevant if you take blood thinners — your physician will review your medications before scheduling.
• Infection. Very rare with sterile technique, but the consequences are serious in the spine.
• Headache. A small risk if the needle inadvertently enters the dural sac (a post-dural puncture headache); usually self-limited.
• Nerve injury. Rare with image guidance and an experienced operator.

Why OSI Doesn’t Do This In-House

OSI does not perform epidural steroid injections in-house. ESIs are an interventional pain management procedure: they require live fluoroscopy, sterile procedure suite setup, and dedicated training that’s outside the OSI orthopedic scope. Patients who need an ESI are referred to a trusted pain management physician we work with, with imaging and records sent ahead so the visit is efficient.

OSI stays involved on the conservative side. We continue physical therapy oversight, medication management, and follow-up so the ESI fits into a larger non-operative plan rather than being a one-off procedure with no continuity of care.

Next Steps

If you think you might be a candidate — or you just want a generalist read on whether this procedure is the right next step — schedule a spine evaluation at OSI or call (830) 625-0009. We will examine you, review imaging you bring with you, and either start a non-operative plan or coordinate the referral to a trusted pain management partner.