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BackTable / MSK / Article
Interlaminar Epidural Steroid Injection: Challenges, Solutions, and Safety Tips
Sam Strauss • Updated Jun 5, 2025 • 37 hits
Successful lumbar epidural steroid injections depend on more than just knowing where the epidural space is. Each case requires real-time decision making based on patient anatomy, prior interventions and intra-operative feedback. Spinal stenosis can limit access, scar tissue can obscure landmarks, and patient medications may shift risk thresholds. Even minor technical choices can make a straightforward procedure become complex without warning, and there’s little room for error in the epidural space. Fluoroscopic visualization, needle trajectory, and steroid selection must all be tailored to the case at hand. When complications occur – such as inadvertent intrathecal entry or motor blockades – the proceduralist must be prepared to pivot quickly and safely.
Explore practical, case-driven considerations for clinicians performing lumbar epidural injections, from the nuances of the interlaminar approach, to the rationale behind different steroid “cocktails,” and practical techniques for minimizing patient risk. In a procedure where small decisions often determine outcomes, breaking your technique down to the fundamentals can help you minimize complications and identify specific scenarios that may require ending a procedure.
This article includes excerpts from the BackTable MSK Podcast, with practical guidance from interventional radiologist Dr. Christopher Beck. You can listen to the full podcast below.
The BackTable MSK Brief
• Interlaminar epidural steroid injections are typically guided by AP and lateral fluoroscopy views, with tactile confirmation via loss of resistance from the ligamentum flavum.
• Dexamethasone is often the steroid of choice due to its particulate-free profile, especially in patients with vascular risk factors.
• Spinal stenosis can alter both needle trajectory and injectate flow; careful angulation and volume adjustments may be needed to move around stenotic anatomy.
• Inadvertent motor blockade is an uncommon but important consideration; it may be influenced by anterior spread or patient-specific anatomic risk factors.
• If intrathecal entry is suspected, clinicians should abort the procedure and reassess imaging to confirm needle position.
Table of Contents
(1) Interlaminar Epidural Steroid Injection Technique
(2) Steroid Selection for Interlaminar Epidural Steroid Injection
(3) Navigating Unintentional Intrathecal Access
Interlaminar Epidural Steroid Injection Technique
Fluoroscopic guidance is the cornerstone of safe and effective lumbar interlaminar epidural injections, allowing clinicians to visualize bony landmarks, navigate complex anatomy, and confirm accurate needle placement. While both AP and lateral views are commonly used, some practitioners advocate for a flexible, tactile-forward approach that emphasizes feel as much as imaging. He underscores the value of “working in the soft tissue,” particularly when guiding the needle through the ligamentum flavum and into the epidural space. Recognizing the characteristic loss of resistance remains a critical skill, especially in patients with distorted anatomy from prior surgery, scoliosis, or advanced degenerative changes.
Needle angle and trajectory also require thoughtful adjustments based on patient-specific factors. A midline approach is sometimes preferred for routine cases, but a shallow paramedian path may be necessary when interlaminar windows are narrowed or asymmetric. Dr. Fishman highlights the importance of treating the process like a “game of inches,” encouraging physicians to picture a bullseye and steer deliberately to avoid bone contact or dural puncture. This methodical approach is especially important when navigating high-risk cases – such as patients with comorbidities or altered spinal landmarks – where a single misstep can compromise efficacy or trigger an avoidable complication.
[Dr. Chris Beck]
Interlaminar – patient's prone, I will stand on patient's left. We have a table that can airplane, tilt side to side. I usually just start with the patient in the just regular prone position and just take a spot of the back. I'll have looked at their cross-sectional imaging at a time, one, to know the level that I want to target and corroborate that with the symptoms. Also it's helpful to me to know about any variant anatomy that might be there, if they have transitional anatomy. I just take a spot, identify where I want to be. I'll do a little level count from the bottom and find the exact location.
One of the things that is important for me and everyone's got their own method, but I'll usually try and flatten out the end plates with a little bit of cranial caudal tilt and true up the end plates. Maybe if I'm going L3, L4, then I'm going to true up the superior end plate of L4, the inferior end plate of L3. Sometimes I have to throw all that out the window and then I'm just looking for this little white space where I'm just rocking the II, either cranial, caudal and sometimes right to left. Usually if it's interlaminar, I'll ask the patients, just tell me which side's the worst.
If it's dead even, that's fine. I'll just pick a side that I think is easier to get into. I find that I always start pyramid line and just try and direct it as towards the center as possible. That's sometimes easier said than done. Sometimes a side can be totally blocked off to you, but with a little needle steerage, I can get it close to midline. If they tell me pain is mostly right sided, then I'm going to go right sided. I also feel like there's a patient in between the ears component that if they tell you all their pains on the right side or majority's on the right side and they have a bandage on the left side, they're like, "Eh."
[Dr. Jacob Fleming]
They didn't get into the right epidural space. I totally agree with that.
[Dr. Chris Beck]
I understand that.
[Dr. Jacob Fleming]
I think that's totally reasonable too. I do the same if there is a laterality to it, then I'll target that. One thing that I learned during residency really is that if you've ever done these under CT, either ESI or blood patch, you'll see regardless of where you inject it, it goes everywhere. It goes ventral, it goes left, it goes right, it goes up, it goes down. For me, the selectivity of the transforaminal, which we'll get to in a second, is, it's not too important, but I think like you said, from the psychological perspective, it's just better, "Oh yes, we went on the left side." Oh wow. My leg pain is gone now." I wouldn't worry too much about that. If we have sciatica, just leg pain in both legs, we go from a left sided approach. You can still expect to get relief bilaterally, but probably the more of the concentration of the medication will be on that laterality.
[Dr. Chris Beck]
I agree. That's a good point to bring up. If you're done in CT, you really see how much coverage you get both ventral, left, right, dorsal. I'm just looking for that little lighter area, which is in between the bony elements. I'll advance the needle, I use a 20-gauge Tuohy needle. Sometimes I use a 22-gauge. The kits come with a 22-gauge, but my preference is to use a 20-gauge. I once had an attending who told me, this was an IR fellowship, Keith Horton. Although I know he doesn't listen. Keith, he told me that anything worth sticking with a 22-gauge needle is worth sticking with a 20-gauge needle. I've taken that to heart with whether it's kidneys, liver, or whatever, abscess drainages. I usually use 20-gauge.
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Steroid Selection for Interlaminar Epidural Steroid Injection
Steroid selection for lumbar epidurals should be patient and pathology specific. Particular steroids (e.g., triamcinolone) may offer longer lasting relief but with increased embolic risk, particularly for transforaminal routes. Non-particulate options (e.g. dexamethasone) provide a somewhat shorter effective period but are often safer in patients with vascular risk factors.
Adjunctive additions like lidocaine or bupivacaine are frequently added to the injection to help manage intra- and post-procedural discomfort and improve for short-term diagnostic clarity. In patients with spinal stenosis or other compressive pathology, lower volumes and concentrations of these adjuncts may be used to reduce the risk of motor blockade or increased pressure. The goal is to strike a balance – achieving therapeutic benefit without compromising safety or diagnostic accuracy.
Clinical experience and patient response inevitably direct longitudinal injection strategy. While some prefer a more conservative starting dose that can be increased if symptom control is insufficient, others may rotate therapeutic agents to reduce the risk of tolerance or cumulative exposure. In all cases, clear documentation and consistent technique help ensure reproducibility, patient safety, and quality outcomes.
[Dr. Chris Beck]
When it comes to caudate equina and going at the stenosis level, I totally agree, but actually go at the level below the stenosis. If they have an L3, L4 stenosis, actually try and go lower than that. The idea behind it is certainly, one, I'll say that those are definitely the patients you can't just blast in the steroid. Actually, I'll say, I think it's usually poor form if you're just blasting this in as quickly as you can get the steroid. It's a nice control. If it feels good, then okay, take it.
That's a real point in the procedure where you can pay attention to your patient. We do all of ours under moderate sedation. Every now and then there's a player who just wants to be local, which is fantastic and fine with me. If they're coming off the table, you can slow down your injection rate. There's no race to get these done. Certainly I'll do a much slower injection rate for patients who are experiencing discomfort when I'm going below the level of stenosis. I just thought, oh, below that way I'm tackling all the nerves that are below the level of stenosis. Then also assume that some of it is tracking up above the stenosis.
[Dr. Jacob Fleming]
For sure. I think that works basically equally as well, just going adjacent to either the surgical or the particularly stenotic level. I agree, we also do the vast majority under moderate, although sometimes we'll do one under local. This might just be if we're having a clinic day and the patient shows up and they have very easy issue to just throw an epidural at.
I like to let patients know, "Hey, you'll probably feel some weird sensation down your legs. That's normal." It's very common to get a paresthesia with the injection of the medication, especially if you're using, lidocaine or bupivacaine in there, which I do. Just tell them that's normal. Some of them get freaked out by it. The patients who've had multiple injections in the past, they're probably fine. I just find that the sensation associated with a lot of these things can be very disconcerting for some patients. I like to let them know, "Hey, this is normal." Having them at a level of sedation where they can appreciate what I'm saying helps a lot.
[Dr. Chris Beck]
Totally agree.
[Dr. Jacob Fleming]
We'll say like technique-wise, I think my approach is pretty similar to yours. Usually get a little bit of oblique to whichever direction you're going to go from, because that can help open up the interlaminar space. However, I would say that's the way that I learned it or I was made to learn it was using just a standard AP view with no oblique. That took me a while to understand. I struggled with that for quite some time. Now I will say I haven't been forced to do that.
It definitely was more versatile and helps me understand the process for, for example, spinal cord stimulator. Blake previously has talked about this, the approach for how you put in the needle for placing a spinal cord stimulator lead. I will say that actually most of the time I do an ESI, I do a very similar trajectory to that of an SES placement. For that, I will start with an AP view, do a little bit of cranial caudal tilt first to crisp up the end plates, like you said. Then some patients just don't have a great interlaminar window. Obviously the patients who have degenerative stenosis is almost always related to degenerative disc disease and collapse of the inner body space and the interlaminar space tends to go with it.
Angulating more caudal gets you more of a view, which makes sense if you think about it, we're coming up from below. That helps a lot. In that case, if I'm not doing any oblique and the interlaminar space is open enough on the straight AP, typically where I will start is around the level of the pedicle below. This is something Dr. Beal referred to as the epidural highway. The way I understand this is basically between the pedicles, the medial borders of the pedicles and basically the laminate below. As long as you go through that path, you have a very good chance of getting into the epidural space.
This allows you to do it without doing an on-foss technique. That being said, I think the on-foss technique, which would be typically what you described as obliquing a little bit, opening up the interlaminar window, and then just starting to place the needle down the barrel, I think that's totally fine. Having learned both ways, I will say that I now prefer the way on a direct AP, but it takes a little bit because you have to, unlike the on-foss approach where you're really just moving in one axis, so to speak, this one you're moving in two or three different axes. You just have to get your brain used to it.
[Dr. Chris Beck]
You talked about the AP projection. Do you ever flip to the lateral projection to see an injection?
[Dr. Jacob Fleming]
Yes. Absolutely do. Thank you for bringing that up. Personally, the way I would do it is, part of it is by feel and part of it is-- You can be a little more methodical about it by measuring roughly the distance on the cross-sectional imaging. Then you can know that, my needle is going to be this many centimeters in before I'm even close to the ligamentum. Once I get to that point where I'm like, "The needle is in a bit," then you can go to the lateral projection.
Some people would use the contralateral oblique. I think there are upsides and downsides to that. I personally prefer a true lateral. What I would do at this point is, I would switch off for my loss of resistance syringe. The way that I've learned this is actually, we didn't use a true loss of resistance syringe, which I think is a great instrument to have available, but we would use our contrast syringe, so 3cc contrast syringe. You see where you are on lateral and you're going to start injecting when you're just posterior to the spinal laminar line. That's the base of the spinous process where it joins with the lamina on the superior aspect. You're drawing this line in your mind's eye from that, the top of the spinal laminar line.
Once you get in there, you're going to feel the resistance. It took me an embarrassing long time to understand, "What the hell is loss of resistance? What is it?" What we're looking for is that feeling of loss of resistance as you go through the ligamentum flavum, because typically the inside the ligament, the pressure is such that you're not going to be able to inject contrast. Obviously if you just slam it in, you can get a sub-ligamentous injection.
Go in, and whether you're going to use a real loss of resistance or the combo LOR contrast thing, which I love that, I don't think I'll ever go back, do that, and then you'll get your epidurogram. If you feel really comfortable and based on where you are, then I think it's fine to start doing the LOR from an AP, but from a true safety perspective, the true lateral I think is the way to go. Once you do that and then you feel the loss of resistance and then in your case, injected, or in my case, that's the same as the LOR, then you step on floor and you get the nice epidurogram.
Of course, if you have any question, if the patient has real severe stenosis, then you can do this under fluoro too. I would do it. I personally don't do it live in the lumbar, but I would say 99% of the time I am getting a lateral view. Then epidurogram has a pretty characteristic appearance, but sometimes it can be like, "Oh, that intrathecal, is it?" I think that's an important thing to talk about. The true epidurogram that is epidural, you can see that the contrast will pass over the pedicle. Whereas the thecal sac does not extend to the pedicle. You won't see that so much.
Those of us who've done a lot of myelography are pretty comfortable seeing what it looks like, but sometimes for whatever reason, you get more of a ventral epidurogram. That can look quite a bit like when you first start injecting for a myelogram, and that can get a little bit tricky. In that case, I would say never be shy about putting in more contrast to get a better feel for where you are. There's a few other characteristic findings, the subarachnoid pattern will be more of an hourglass shape and goes straight up. Like I said, it doesn't drape over the pedicles as the epidurogram does. If you see that nice epidurogram, even from the lateral aspect and you know you're in, I think that's fine. If there's ever any question, come back to AP, take a look there. Just do not, under any circumstances, inject unless where you are for sure. Like I said, because then you definitely will get a motor block and the patient will not be happy with you.
Navigating Unintentional Intrathecal Access
Although unintentional intrathecal access during a lumbar epidural injection is uncommon, it remains a significant complication moment that requires immediate identification and response. Free-flowing CSF is confirmatory for a dural puncture and warrants immediate termination of the procedure. Intrathecal steroid injection is contraindicated regardless of agent or dose due to the high risk of high spinal anesthesia, motor blockade and respiratory compromise.
Management of a dural puncture relies on clear communication and a predetermined plan for procedural termination and reassessment of future interventions. Switching to a caudal or contralateral interlaminar approach can be done on some patients, but patients should be counseled on the risk of a post-dural puncture headache and an epidural blood patch should be considered if symptoms develop during post-procedural monitoring.
Early recognition of intrathecal access is the most important part of minimizing complication risk in these procedures. Subtle changes in needle resistance, unexpected CSF return and abnormal contrast spread under fluoroscopy should all raise immediate concern. If there is any doubt – don’t inject. The risk of an intrathecal injection is great enough that any question of appropriate access should end the procedure.
[Dr. Chris Beck]
Let me ask you this. If you say you're doing your injection for whatever reason, you end up intrathecal, what's your next step as far as completing the procedure? Do you abandon the procedure? Do you go to a different level? I've just heard people are just all over the map and their approach to this. Some people can be very dogmatic. I'm interested in your take.
[Dr. Jacob Fleming]
Sure. It's a really great question. I've frankly been taught different ways. In residency, it was, if you got CSF back while doing an ESI, you got to abort the procedure for the day, call it a day and go home. I don't think that's necessarily true. I would say abandon that level, for sure, and go to an adjacent level. I really don't think that it is the end of the world to get intrathecal, but you need to be aware. I think it's appropriate to tell the patient about this that they may have a spinal headache after.
In that case, if they have that, and it persists for a few days, I would tell them, "Look, take--" Fioricet can actually really help and just hydration. Most of these dural punctures are going to be just fine without any further intervention. If after a few days, they're still having that spinal headache, blood patch is an easy thing. We can talk about that some other time.
The access for a blood patch is exactly the same as an ESI. In that case, I would go at the level where you either presumably or definitely had the dural puncture and do that. What I learned in my fellowship is that it's not a contraindication to go ahead with the ESI, but go at a different level so that you have a much less chance of getting any of that spinal action.
[Dr. Chris Beck]
I agree with that. It's strange that I also learned in training, when I got a little bit of training on these, that there were some neurorads who just abandoned the whole process like, "Oh, we got to bring them back on a different day. My practice currently is if for some reason I'm an intrathecal, then just take that needle out." Sometimes it's a little bit painful. It's not often with interlaminar, but sometimes you're working to get into this one spot and then you finally get in and then it doesn't work out and so you have to drop into another level.
Podcast Contributors
Dr. Christopher Beck
Dr. Chris Beck is a practicing interventional radiologist with Regional Radiology Group in New Orleans.
Dr. Jacob Fleming
Dr. Jacob Fleming is a diagnostic radiology resident and future MSK interventional radiologist in Dallas, Texas.
Cite This Podcast
BackTable, LLC (Producer). (2024, August 6). Ep. 55 – BackTable Basics: Lumbar Epidural Injections [Audio podcast]. Retrieved from https://www.backtable.com
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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