S1 radic - S1 TF vs L5-S1 IL?

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One of our attendings teaches that an S1 TF injection really doesn't get a bolus of steroids close to the S1 nerve root. He pushes for doing an L5-S1 IL injection instead. Yet often when I take a patient with likely S1 radiculitis and inject a little bupi and Kenalog in the foramen (2 mL), the patient gets excellent relief- at least until the end of the visit. My attending's point makes sense if you consider where the pathology compressing the S1 nerve usually occurs (L5-S1). OTOH, my experience injecting at S1 (with other attendings) makes sense in terms of where the nerve lives distally (ie. I think I'm numbing up the nerve where it turns the corner to pop out the anterior S1 foramen- but perhaps NOT putting steroid in the vicinity of the pathology).

What do you think?

Originally Posted by powermd

One of our attendings teaches that an S1 TF injection really doesn't get a bolus of steroids close to the S1 nerve root. He pushes for doing an L5-S1 IL injection instead. Yet often when I take a patient with likely S1 radiculitis and inject a little bupi and Kenalog in the foramen (2 mL), the patient gets excellent relief- at least until the end of the visit. My attending's point makes sense if you consider where the pathology compressing the S1 nerve usually occurs (L5-S1). OTOH, my experience injecting at S1 (with other attendings) makes sense in terms of where the nerve lives distally (ie. I think I'm numbing up the nerve where it turns the corner to pop out the anterior S1 foramen- but perhaps NOT putting steroid in the vicinity of the pathology).

What do you think?

Your attending needs a little same side lateral rotation and rosstral tilt on the intensifier. Then he can see down the barrel of the posterior foraminal opening and stop being a chicksht about getting the medicine to the right spot. Before injecting any contrast, get a lateral and check depth in the canal: too far anterior and you get nothing but S1 and nothing to ascend that 2-3cm upto the L5-S1 disc.

Originally Posted by powermd

One of our attendings teaches that an S1 TF injection really doesn't get a bolus of steroids close to the S1 nerve root. He pushes for doing an L5-S1 IL injection instead. Yet often when I take a patient with likely S1 radiculitis and inject a little bupi and Kenalog in the foramen (2 mL), the patient gets excellent relief- at least until the end of the visit. My attending's point makes sense if you consider where the pathology compressing the S1 nerve usually occurs (L5-S1). OTOH, my experience injecting at S1 (with other attendings) makes sense in terms of where the nerve lives distally (ie. I think I'm numbing up the nerve where it turns the corner to pop out the anterior S1 foramen- but perhaps NOT putting steroid in the vicinity of the pathology).

What do you think?

With your TFESI, the flow is typically cephalad, so 3mL is most likely going to make it up to L5/S1 disc space (anteriorly).

I remember hearing, at the ISIS imaging course, that on average, it takes about 1 1/2 spinal levels with an interlaminar for the injectate to travel cephalad and wrap around the thecal sac (asssuming the needle tip is roughly in the midline), e.g. if you're targeting an L3/4 disc inject at L4/5 or L5/S1.

For your scenario above, I would keep doing your S1 TFESI or caudal +/- cath.

i struggle with scenarios like this all the time. ie: what is the best injection for one particular problem. i dont think there is a "right" answer here. ask 5 different people, you may get 5 different answers. i tend to try to go with the philosophy that if you are performing only one injection, go with a TFESI vs. a ILESI. also, if you are relatively sure that the pathology is at one particular level, only inject that level. this way, you get the most medicine closest to where you think the pathology is. personally, id also do a S1 TFESI

Originally Posted by powermd

One of our attendings teaches that an S1 TF injection really doesn't get a bolus of steroids close to the S1 nerve root. He pushes for doing an L5-S1 IL injection instead. Yet often when I take a patient with likely S1 radiculitis and inject a little bupi and Kenalog in the foramen (2 mL), the patient gets excellent relief- at least until the end of the visit. My attending's point makes sense if you consider where the pathology compressing the S1 nerve usually occurs (L5-S1). OTOH, my experience injecting at S1 (with other attendings) makes sense in terms of where the nerve lives distally (ie. I think I'm numbing up the nerve where it turns the corner to pop out the anterior S1 foramen- but perhaps NOT putting steroid in the vicinity of the pathology).

What do you think?

but why does he want to do an L5-S1 IL versus TFESI at L5-S1? I can see the point of doing it the level of the compression, but i dont know why he saying do IL at this level... unless im missingsomething. Its late and my 2 year old has destroyed me today, so maybe i am...

I tend to treat the dermatomal distribution of pain. Occasionally I'll do two levels to "cover all the bases". Mostly transforaminals, except in postsurgery and old patient multilevel bad stenosis--then caudal cath or rarely bilateral S1 TF (again depending on distribution of pain. Interlaminar cath for thoracic, enter at L2/3 and guide a slightly bent epidural catheter where it needs to go (I've heard about some nasty thoracic stuff). Interlaminar for cervical.

Originally Posted by DocShark

but why does he want to do an L5-S1 IL versus TFESI at L5-S1? I can see the point of doing it the level of the compression, but i dont know why he saying do IL at this level... unless im missingsomething. Its late and my 2 year old has destroyed me today, so maybe i am...

A posterolateral/paracentral disc herniation at L5/S1 compresses the S1 root (unless it is a far lateral or foraminal herniation in which case it compresses L5), so S1 TFESI. A TFESI at the L5/S1 foramen is probably going to track up to the L4/5 disc and miss the herniation at L5/S1.

I wouldn't think that injectate from an L5/S1 interlaminar would wrap around the thecal sac at that level unless you put the needle far off the midline.

My best guess is this is your attending's rational to be lazy; an S1 TFESI is a little slower to do than an ILESI, especially with a resident or fellow.

Just do an S1 TFESI under live fluoro and watch the contrast track up to the L5/S1 disc and show your attending THAT and see what he says to argue with you.

Originally Posted by Disciple

A posterolateral/paracentral disc herniation at L5/S1 compresses the S1 root (unless it is a far lateral or foraminal herniation in which case it compresses L5), so S1 TFESI. A TFESI at the L5/S1 foramen is probably going to track up to the L4/5 disc and miss the herniation at L5/S1.

I wouldn't think that injectate from an L5/S1 interlaminar would wrap around the thecal sac at that level unless you put the needle far off the midline.

But what if he aims the needle caudally?

I'm positive the attending never learned to read fluoro well enough and missed too many and now just has confidence issues. Only other concern would be attending has no concept of epidural anatomy and thinks he can reach below the injected level consistently. Attending is an anesthesiologist correct?

Tell him to make it a hypobaric epidural and all will be solved.

[quote=Disciple;7797680]A posterolateral/paracentral disc herniation at L5/S1 compresses the S1 root (unless it is a far lateral or foraminal herniation in which case it compresses L5), so S1 TFESI. A TFESI at the L5/S1 foramen is probably going to track up to the L4/5 disc and miss the herniation at L5/S1.


i disagree. i understand that a L5-S1 disc herniation, more central, is likely to compress the S1 nerve, and when i do L5-S1 TFESI, I do get L5 spread, but I usually get more S1 spread. More than anything the bulk of the medication is placed at the site of the compression, at the level of the disc, IMHO. I rarely do S1 TFESI. I have, but basically stopped as i didnt think the results were as good at L5-S1. I typically treat S1 radics with L5-S1 TFESI, and get appropriate results in m opinion. I go at the level of the disc. This is my approach at least, as well as my partners, and many other people i know. But i agree, many ways to skin a cat.

I ve seen this alot, this disparity in approach, and it appears to be often how someone was trained. It seems to me anesthesia trained typically go at the level of the disc, L5-S1 TFESI for S1 radic, and PM&R trained go at the S1 foramen. Atleast this appears to be my impression from talking to be about this issue over the last few years. Im always interested in the different approaches. Maybe i'm in the minority.

can i take a poll where one addresses S1 radic FROM L5-S1 disc, where they target S1 foramen or L5-S1? Thanks

You know, i was talking to a freind of mine that trained about the same time as i did, and his approach to S1 radic from a L5-S1 HNP/bulge is to try L5-S1 TFESI initially. If results arent great, he adds S1 to the L5-S1. He states he does this does this 20-25% of time in his estimation. I think there is some rationale to this (no evidence of course). Anyone do this? I think i will consider this next time.

Originally Posted by Ligament

My best guess is this is your attending's rational to be lazy; an S1 TFESI is a little slower to do than an ILESI, especially with a resident or fellow.

Just do an S1 TFESI under live fluoro and watch the contrast track up to the L5/S1 disc and show your attending THAT and see what he says to argue with you.

Sorry to disagree but I think a S1 TFESI is one of the quickest injections we do...particularly compared to trying to do a ILESI correctly.

Originally Posted by DocShark

i disagree. i understand that a L5-S1 disc herniation, more central, is likely to compress the S1 nerve, and when i do L5-S1 TFESI, I do get L5 spread, but I usually get more S1 spread. More than anything the bulk of the medication is placed at the site of the compression, at the level of the disc, IMHO. I rarely do S1 TFESI. I have, but basically stopped as i didnt think the results were as good at L5-S1. I typically treat S1 radics with L5-S1 TFESI, and get appropriate results in m opinion. I go at the level of the disc. This is my approach at least, as well as my partners, and many other people i know. But i agree, many ways to skin a cat.

I see your point. I do sometimes see the contrast flow towards the midline in addition to flowing cephalad.

I still think an interlaminar at the level of the herniation is likely to miss though.

If you know what you're doing with fluoro, an S1 transforaminal is one of the quickest. But it doesn't always pop out at you in a straight AP view, whereas an L5-S1 IL approach does. I've seen quite a few S1 TF contrast injections spread to the L5-S1 disc and then along the L5 nerve root. If my goal is therapeutic and I see that, I'm done. If not, sometimes I'll add an L5-S1 TF.

Originally Posted by Disciple

I see your point. I do sometimes see the contrast flow towards the midline in addition to flowing cephalad.

I still think an interlaminar at the level of the herniation is likely to miss though.

agreed about IL

[QUOTE=DocShark;7798419]

Originally Posted by Disciple

A posterolateral/paracentral disc herniation at L5/S1 compresses the S1 root (unless it is a far lateral or foraminal herniation in which case it compresses L5), so S1 TFESI. A TFESI at the L5/S1 foramen is probably going to track up to the L4/5 disc and miss the herniation at L5/S1.


i disagree. i understand that a L5-S1 disc herniation, more central, is likely to compress the S1 nerve, and when i do L5-S1 TFESI, I do get L5 spread, but I usually get more S1 spread. More than anything the bulk of the medication is placed at the site of the compression, at the level of the disc, IMHO. I rarely do S1 TFESI. I have, but basically stopped as i didnt think the results were as good at L5-S1. I typically treat S1 radics with L5-S1 TFESI, and get appropriate results in m opinion. I go at the level of the disc. This is my approach at least, as well as my partners, and many other people i know. But i agree, many ways to skin a cat.

I ve seen this alot, this disparity in approach, and it appears to be often how someone was trained. It seems to me anesthesia trained typically go at the level of the disc, L5-S1 TFESI for S1 radic, and PM&R trained go at the S1 foramen. Atleast this appears to be my impression from talking to be about this issue over the last few years. Im always interested in the different approaches. Maybe i'm in the minority.

can i take a poll where one addresses S1 radic FROM L5-S1 disc, where they target S1 foramen or L5-S1? Thanks

I am biased since I don't do IL, only TF, but I have struggled with the single or double approach. I feel that less is always better, so i will always try an S1 first. The few times that I have tried both the L5 and S1 together, it has produced good results. I have trouble with the concept of doing this every time, since my single S1 injections do just fine...(it all depends on whether or not there is good epidural flow, like steve said....and only YOU know if it looks good). Having said that, I have had plenty of caudal spreads with minimal L5/S1 flow do great). All you need to do is check an AP after your medicine has been injected at the S1 to realize many times it gets up to L3 or L4. Someone also mentioned doing the L5/S1 foramen with good flow, and of course there will occasionally be S1 overflow, but IMHO slightly more risky and certainly more technical secondary to stenosis, increased lordosis, dura, etc...

i have pretty good results with doing L5 TFESI for L5 disc herniations compressing S1.... occasionally i will augment with S1 TFESI.

i don't do Inter-laminars excet for cervical... it has been almost 2 years now since my last lumbar inter-laminar...

There's a couple of articles comparing TFESI injections at the level of a paracentral herniation v. a TFESI of the involved nerve root.

Here's the prospective study from 2007. 20% of patients had radicular symptoms with central stenosis rather than a HNP...

Don't think there is a right answer of which level; but I wouldn't do the interlaminar IMHO

Those that do S1 for L5-S1 disc, as discussed above, are you also doing L5-S1 TFESI (L5) for L4-5 disc hitting L5. Again I go at L4-5 without issue, IMO. But interested in thoughts...

Originally Posted by DocShark

Those that do S1 for L5-S1 disc, as discussed above, are you also doing L5-S1 TFESI (L5) for L4-5 disc hitting L5. Again I go at L4-5 without issue, IMO. But interested in thoughts...

I go for the effected nerve root 1st, and if no response, go for the level of involved disc.

So for L4-5 hitting L5, I go for L5-S1 TFESI, if no response, L4-5 TFESI

it is interesting how confident we talk about pain/nerve root distributions...

we are basing our convictions on MRI imaging (which isn't ALL that when it comes to figuring out which nerve is more pinched - L5 or S1) and our antiquated notion of dermatomal maps that were based on a few anatomic studies on a few shingle patients a hundred years ago.

i have done needle stimulation at nerve roots (after hearing Ken Alo - Houston - talk about it), and have been surprised to see patients describe L2-L3 "dermatomal" pain when stimulating L5... have been surprised to see patients describe S2-3 dermatomal pain when stimulating L1/L2... there is a lot of cross-talk, a lot of spinal cord mapping issues that we just don't understand (yet)...

so the question is then: do we treat site of pathology or presumed dermatomal pattern based on antiquated notions... i have had a FAR higher success rate treating site of injury than dermatomal or myotomal patterns

Originally Posted by Tenesma

it is interesting how confident we talk about pain/nerve root distributions...

we are basing our convictions on MRI imaging (which isn't ALL that when it comes to figuring out which nerve is more pinched - L5 or S1) and our antiquated notion of dermatomal maps that were based on a few anatomic studies on a few shingle patients a hundred years ago.

i have done needle stimulation at nerve roots (after hearing Ken Alo - Houston - talk about it), and have been surprised to see patients describe L2-L3 "dermatomal" pain when stimulating L5... have been surprised to see patients describe S2-3 dermatomal pain when stimulating L1/L2... there is a lot of cross-talk, a lot of spinal cord mapping issues that we just don't understand (yet)...

so the question is then: do we treat site of pathology or presumed dermatomal pattern based on antiquated notions... i have had a FAR higher success rate treating site of injury than dermatomal or myotomal patterns

sometimes its clear: L5-S1 paracentral herniation touching S1, plantar flexion weakness, S1 dermatomal distribution pain, no achilles reflex. = S1 transforaminal

more often, its not: scattered stenosis, PE findings unclear, ?dermatomal distribution. in this case, i go with my best guess, but often times do a 2 level transforaminal b/c it really isnt all that clear. i feel with 2 levels, ill covermy bases.

just had a patient with HUGE L5 disc compressing everything but symptoms in S1 distribution (despite my previous diatribe re: dermatomes)... did a single level S1 TFESI with fantastic relief.

Originally Posted by Tenesma

just had a patient with HUGE L5 disc compressing everything but symptoms in S1 distribution (despite my previous diatribe re: dermatomes)... did a single level S1 TFESI with fantastic relief.

That's just called good doctor.

Match imaging to history to physical then choosing appropriate treatment.

Interesting article supporting TFESI at level of disc injury (preganglionic) vs level of exiting NR (postganglionic).

Interesting paper. The risk of the Korean radiologists approach: 1. They may spear the nerve with their sharp spinal needle 2. they may be injecting within the dural cuff. 3. annular bulging or HNP injected with a sharp needle at or just superior to the level of the disc may easily result in an intra-annular or intradiscal injection. If they had used a blunt needle, all these would have been averted.
The S1 exiting nerve injection does work well, requires very low volumes compared to the interlaminar approach (as long as the contrast tracks at least to the midpoint of the crossing of the nerve at the disc) , and is more reliable than the interlaminar shotgun approach of injecting larger volumes of dilute steroid posterior to the dura hoping to track all the way around the lateral and into the anterior epidural space.
A third way to approach this is via blunt needle at the disc level directly into the anterior epidural space using a curved tip for maneuvering and with an initial approach far lateral with a 30 degree angle to the coronal plane. This traversing nerve approach permits placement directly onto the herniation at the point of the traversing nerve and permits use of very low volume concentrated steroid.