An epidural steroid injection places anti-inflammatory medication into the epidural space — the thin layer surrounding the sac that holds the spinal cord and nerve roots. The aim is not to repair a disc or widen a narrowed canal. It is to reduce the inflammation around an irritated nerve so the pain settles enough for movement, therapy and time to do the rest.
It is one of the most commonly performed procedures in interventional pain practice, for the simple reason that the problem is nearly universal. As Dr. María Alejandra De La Peña opens her course on the subject, in the United States “at least 25% of the population, at any time of their life, they will experience low back pain, at any age.” Her own practice spans that range exactly — “my youngest patient is 18, from a sports injury, and my oldest patient is 103, from the degeneration.”
This reference covers what the injection treats, how the three approaches differ and when each is chosen, which steroid is used and why that choice matters, and the complications worth understanding before consenting. It sits under our clinical reference to interventional pain procedures.
What an epidural steroid injection treats
The injection targets inflammation around a nerve, so it is offered where a nerve is being irritated or compressed. De La Peña lists the conditions it is used for: nerve root impingement, spinal stenosis, disc herniation and discogenic pain.
The purpose, in her framing, is broader than pain relief alone — “reducing inflammation, improved lifestyle, improved functionality of the patient.” That matters clinically, because an injection that buys a patient six weeks of tolerable movement has done its job even if the pain eventually returns. It creates the window in which rehabilitation is possible.
What it does not do is change the structure. A herniated disc is still herniated, and a stenotic canal is still narrow.
The epidural space, and why the technique is what it is
The epidural space is, as De La Peña describes it, “a virtual space” between the ligamentum flavum and the dura, running from the foramen magnum down to the sacral hiatus and containing fat, a venous plexus and nerve roots.
Reaching it means passing through successive ligaments — supraspinous, then interspinous, then ligamentum flavum. The ligamentum flavum is the landmark, because it is dense, and the moment the needle passes through it the resistance disappears. That is the loss of resistance technique, performed with either air or saline.
What follows is the part that prevents the worst outcomes. The needle is aspirated to confirm neither blood nor cerebrospinal fluid returns — if either does, the needle is repositioned. Then contrast is injected under fluoroscopy to confirm the spread is where it should be. De La Peña is unambiguous about why: if the dura is penetrated and steroid is injected into the intrathecal space, the consequences include arachnoiditis and nerve damage. In her words, contrast “is extremely important to avoid complications.”
Fluoroscopy provides the map. The vertebral landmarks form the familiar “Scotty dog” silhouette, and most interventional spine procedures are oriented around it.
Transforaminal, interlaminar and caudal: how the approach is chosen
Three routes reach the same space, and the choice follows the symptom pattern rather than preference.
Interlaminar enters between the laminae in the midline and delivers medication broadly across several levels. De La Peña's rule is that where a patient has both back and leg pain, “it's better to start with a lumbar interlaminar epidural injection.”
Transforaminal is a selective nerve root technique, delivering medication to one specific root where it exits the spine. It is chosen for predominantly radicular symptoms — in her phrasing, “if the patient goes to your office and tells you, I only have sciatica, then a selective nerve root block, transforaminal epidural approach, is a better option.”
Caudal enters through the sacral hiatus at the base of the spine. Its distinctive use is in patients who have had previous surgery: those “fused all the way down to L5-S1 develop a lot of adhesions, and these injections on this approach with a catheter will help release the tissue and improve the pain of the patient.”
Previous surgery also rules approaches out. After a laminectomy the interlaminar route is not recommended, because the anatomy is distorted and, as she puts it, there is “a high risk of having intrathecal uptake.” A transforaminal approach is used instead.
The approaches are compared in detail in transforaminal vs interlaminar vs caudal.
Particulate and non-particulate steroid, and why the approach decides it
This is the single most consequential drug decision in the procedure, and it is not about potency.
Steroids injected into the epidural space fall into two groups. Particulate steroids are depot preparations — they form a suspension, sit where they are placed and last longer. De La Peña ranks them from most to least particulate: methylprednisolone, triamcinolone, betamethasone. The tradeoff is direct: “they're supposed to last longer. However, at the same time they have a higher risk of complications.”
Non-particulate steroid — dexamethasone is the one in common use — dissolves fully. That makes it, in her words, “usually safer, because they have a less risk of embolization and cause of arachnoiditis or nerve damage.” The cost is duration: dexamethasone “can have a shorter duration of action.”
The approach then decides the choice. Triamcinolone is recommended for the interlaminar route. For transforaminal work, non-particulate is safer “because of all the structures that are surrounding, including nerves and arteries” — the concern being that a particulate suspension entering a radicular artery cannot pass through it.
Typical dosing she describes runs 40 to 80 mg for interlaminar, and about half that for transforaminal.
The diabetic patient
Epidural steroid raises blood glucose, and the effect is not brief. De La Peña describes rebound hyperglycaemia lasting several days and adjusts for it: diabetic patients often receive a reduced dose, and are told to check their glucose for “usually the first three to five days.”
Where control is tight or insulin-dependent, she involves the endocrinologist to adjust medication “just for that amount of time, until the peak of the steroid stabilises the glucose.”
This is worth raising at consent rather than discovering afterwards.
Complications worth understanding
Most are transient. Two are emergencies.
Dural puncture and positional headache. A micro-leak of cerebrospinal fluid can occur even when aspiration and spread looked correct. De La Peña describes managing it conservatively first — hydration, NSAIDs, rest — and if after two or three days it has not improved or is worsening, performing an epidural blood patch with roughly 20 mL of the patient's own blood, which typically resolves the headache within a day.
Epidural haematoma is the reason the anticoagulation history matters more than any other question asked before the procedure. She lists the agents now routinely encountered — aspirin, apixaban, rivaroxaban, edoxaban — and points to the ASRA guidelines that specify how long each must be held before a neuraxial block and when it may resume. The presentation overlaps with epidural abscess: new motor or sensory deficit, or cauda equina symptoms. Either demands urgent MRI.
Infection is prevented by sterile technique, with higher risk in diabetic, immunosuppressed and MRSA-colonised patients. An untreated superficial infection can progress to epidural abscess, discitis or osteomyelitis.
Vasovagal syncope is, in her experience, “very common, especially in strong young patients” — anxiety rather than the drug. Management is supine positioning, knees bent, fluids and reassurance.
Transient effects she describes as routine: post-procedure pain settled with ice, NSAIDs or a muscle relaxant; contrast allergy and rash, which are “quite common”; and a short-lived rise in blood pressure and glucose, facial flushing, hiccups, anxiety and insomnia.
Reading the imaging against the patient
MRI guides the decision, but does not make it. De La Peña teaches the basic sequences — T1, T2 and STIR — on the grounds that “we're not radiologists, but we need to know how to read the basics of a spine MRI.”
Her governing rule is stated repeatedly and is the most important sentence in the course: “We always have to correlate images with symptoms, not just images.”
Dermatomal mapping is how that correlation is made. A patient describing pain down the front of the thigh into the top of the foot is describing an L4-L5 distribution, and the imaging should be interrogated at those levels rather than at whatever looks worst on the scan. Examining the patient, she adds, is what “guarantees the best success of your treatments.”
For clinicians
Epidural technique is learned under supervision, on real anatomy, with a proctor watching. This reference carries no needle depths or angles for that reason. Empire teaches the lumbar epidural approaches, fluoroscopic anatomy and complication management across the pain management academy.
Learn blocks with your hands, not from a page
Empire’s Pain Management Training (THE Pain Show) is accredited for 25.25 AMA PRA Category 1 Credits™, jointly provided by AKH, Inc, and Empire Medical Training. For narrower peripheral work, Joint, Extremity and Non-Spinal Injection Training carries 6.75 credits for the complete in-person hybrid program, and Advanced Musculoskeletal Ultrasound Guided Injections builds the guidance skills above.
Claim Your Prize!