Dr. Furman's article in this month's Pain Physician re "SNRBs"

[ampaphb]

[FONT=Verdana,Geneva,Arial,Helvetica,sans-serif][FONT=Trebuchet MS,Verdana,Helvetica,sans-serif][FONT=Verdana,Geneva,Arial,Helvetica,sans-serif]http://www.painphysicianjournal.com/2008/december/2008;11;855-861.pdf...

Seems to me what this says is that no volume over 0.5cc can be considered selective. The problem is, I suspect most will read that to also mean 0.5cc IS selective.

What Furman says is that the CONTRAST INITIALLY stays unilateral and within one level if injected at 0.5cc or less. No comment is made about the local anesthetic, nor what happens to the solutions in question once you get the patient up.

To me, this is a dangerous article, not because of what it actually concludes, but rather because of what folks assume it implies.

For my money, there remains no such thing as a truly selective nerve root block, and anyone who allows a surgeon to rely on such nonsense in his pre-operative staging is doing their patient a huge disservice.

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[PMR 4 MSK]

So you're going to need to do a total of less than 0.5 cc of all injectate to get a potential SNRB. Who can do that with enough contrast to ensure correct placement and enough local to get a block? If you get it exactly right, maybe you could use 0.1 - 0.2 contrast and .3 - .4 of local, pasrticularly higher concentration like 2% lido, but is that enough for a larger nerve like a root? That also precludes use of steroid, but why use steroid if you are trying for a SNRB (I don't know, but I see it in reports all the time)?

I stopped believing in SNRBs a few years ago. I call them all TFESIs.

Interstingly I have some that 90% of the contrast goes distal along the nerve root. Then post injection, I'll see a smidge intraspinal. I'd like to have some walk around for a few minutes and then re-image. Anyone done that?

 

[SSdoc33]

[FONT=Verdana,Geneva,Arial,Helvetica,sans-serif][FONT=Trebuchet MS,Verdana,Helvetica,sans-serif][FONT=Verdana,Geneva,Arial,Helvetica,sans-serif]http://www.painphysicianjournal.com/2008/december/2008;11;855-861.pdf...

Seems to me what this says is that no volume over 0.5cc can be considered selective. The problem is, I suspect most will read that to also mean 0.5cc IS selective.

What Furman says is that the CONTRAST INITIALLY stays unilateral and within one level if injected at 0.5cc or less. No comment is made about the local anesthetic, nor what happens to the solutions in question once you get the patient up.

To me, this is a dangerous article, not because of what it actually concludes, but rather because of what folks assume it implies.

For my money, there remains no such thing as a truly selective nerve root block, and anyone who allows a surgeon to rely on such nonsense in his pre-operative staging is doing their patient a huge disservice.

agreed completely. essentially, the article supports the use of using 0.5 mL or less to perform a procedure that some would argue should not even be performed at all.

 

[mille125]

So you're going to need to do a total of less than 0.5 cc of all injectate to get a potential SNRB. Who can do that with enough contrast to ensure correct placement and enough local to get a block? If you get it exactly right, maybe you could use 0.1 - 0.2 contrast and .3 - .4 of local, pasrticularly higher concentration like 2% lido, but is that enough for a larger nerve like a root? That also precludes use of steroid, but why use steroid if you are trying for a SNRB (I don't know, but I see it in reports all the time)?

I stopped believing in SNRBs a few years ago. I call them all TFESIs.

Interstingly I have some that 90% of the contrast goes distal along the nerve root. Then post injection, I'll see a smidge intraspinal. I'd like to have some walk around for a few minutes and then re-image. Anyone done that?

i agree...they are all TFESI's

 

[lobelsteve]

I just like the sound of SNURB better than TAFEZI.
Similar to FAJINBE vs. MBB

As far as the science- agreed.
And no, I do not walk patients around ang get them back on the table.
But maybe I should. Or we all should as part of a mutlicenter study on the effects of 60 seconds ambulation on contrast flow patterns?

Anyone game?

Only issues: we would need to standarize our TFESI injectate.
I use 2cc NSS and 2CC Celestone.
I can get Celestone for $18.50 per 5cc.

 

[Tenesma]

agreed --- however, i do feel that patients who do well w/ TFESI tend to do better post-decompression than patients who don't respond to TFESIs...

 

[PMR 4 MSK]

I did a L4-5 TFESI today on a patient, then asked her to walk around for a couple minutes, the re-imaged her. There really wasn't much difference in the spread of the contrast - just a little more faint. I forgot to bring home the images to scan, will try to get them tomorrow.

 

[mdvol]

I was a fellow of Dr. Furman's during his putting together of the article - not during data collection, although I did help collect some imaging for S1 TFESI's. I am pretty sure Dr. Furman doesn't believe in the concept of SNRB either and just hope the article is not leading others to think he is saying 0.5cc is selective. Amphb is right that he is only commenting on the nature of the contrast spread as we used to debate viscosity and other rheologic properties of local anesthetic and steroid making it even less "selective".

 

[SpineCareDoc]

When I am attempting to do a diagnostic transforaminal injection, without steroid, my goal is to make certain that the local does not travel significantly medial to the pedicle. To do so, I take 1cc of 4% lidocaine and mix with 1cc of Omnipaque 300. So what I am using for the procedure is the equivalent of Omnipaque 150 / 2% Lidocaine. I will inject under live fluoro, and observe flow live. If I get flow medial to the pedicle, I will not consider the diagnostic result of the procedure to be valid. I came to be comfortable this method after hearing Bogduk discuss possible techniques at ISIS with the physicians in attendance.

There is considerable literature out there regarding whether a "nerve root block" can be truly selective. There is even literature which uses electrical stimulation with an insulated needle to verify needle position close to the target structure.

We live in a world where proceduralists, who do not care about any of this, dump 2cc of Marcaine via transforaminal route. The patient gets 100% relief after which the proceduralist informs the surgeon (who does not understand any of this and does not care to learn) that the patient had 100% relief. The surgeon then happily operates on the patient. When the patient does not get relief from surgical intervention, it is off to the pain management center with a referral that reads "please assume care of the patient."

It is certainly better to light a candle than curse the darkness, however, I am not hopeful.

 

[PMR 4 MSK]

When I am attempting to do a diagnostic transforaminal injection, without steroid, my goal is to make certain that the local does not travel significantly medial to the pedicle. To do so, I take 1cc of 4% lidocaine and mix with 1cc of Omnipaque 300. So what I am using for the procedure is the equivalent of Omnipaque 150 / 2% Lidocaine. I will inject under live fluoro, and observe flow live. If I get flow medial to the pedicle, I will not consider the diagnostic result of the procedure to be valid. I came to be comfortable this method after hearing Bogduk discuss possible techniques at ISIS with the physicians in attendance.

Certainly a step in the right direction, but in most cases, the patient will not know if the block was succesful for their pain until they get up and move around, unless they have pain at rest, and then you don't know where the lido is several minutes later. Couple that with lido usually giving a motor block and they won't be able to walk very well in a lot of cases I would suspect.

Where do you position the tip of the needle when you do this?

 

[Aether2000]

I have oft wondered what is the point of blocking a nerve peripheral to the pathology? If the issue is foraminal stenosis then a block of the nerve in the NF is appropriate, but if it is from the disc above, how can an injection of local anesthetic well below the pathology give any information? It would be similar to doing sciatic nerve blocks for a disc herniation (yes, Virginia, there is a local physician that actually does this).

 

[PMR 4 MSK]

I have oft wondered what is the point of blocking a nerve peripheral to the pathology? If the issue is foraminal stenosis then a block of the nerve in the NF is appropriate, but if it is from the disc above, how can an injection of local anesthetic well below the pathology give any information? It would be similar to doing sciatic nerve blocks for a disc herniation (yes, Virginia, there is a local physician that actually does this).

Will there be any intra-neural uptake of the local, allowing it to travel a cm or two to the DRG, if it is done in close proximity such as extra-foraminal? I.e. will it/can it result in DRG anesthesia?

 

[Aether2000]

I agree, the DRG certainly has involvement with foraminal stenosis but is there any DRG involvement when there is a preganglionic compression of the traversing spinal nerve?

 

[SSdoc33]

When I am attempting to do a diagnostic transforaminal injection, without steroid, my goal is to make certain that the local does not travel significantly medial to the pedicle. To do so, I take 1cc of 4% lidocaine and mix with 1cc of Omnipaque 300. So what I am using for the procedure is the equivalent of Omnipaque 150 / 2% Lidocaine. I will inject under live fluoro, and observe flow live. If I get flow medial to the pedicle, I will not consider the diagnostic result of the procedure to be valid. I came to be comfortable this method after hearing Bogduk discuss possible techniques at ISIS with the physicians in attendance.

There is considerable literature out there regarding whether a "nerve root block" can be truly selective. There is even literature which uses electrical stimulation with an insulated needle to verify needle position close to the target structure.

We live in a world where proceduralists, who do not care about any of this, dump 2cc of Marcaine via transforaminal route. The patient gets 100% relief after which the proceduralist informs the surgeon (who does not understand any of this and does not care to learn) that the patient had 100% relief. The surgeon then happily operates on the patient. When the patient does not get relief from surgical intervention, it is off to the pain management center with a referral that reads "please assume care of the patient."

It is certainly better to light a candle than curse the darkness, however, I am not hopeful.

careful, spincaredoc, you are barking up the wrong tree with this crew when you talk about "spinal nerve blocks" and mechanisms of pain relief. i tried to take your angle a few months ago and didnt get any takers. i do, however, perform these procedures very similarly to the way you do and call them "spinal nerve blocks". i tried to look up and postulate a mechanism for how this would work, but there really isnt all that much out there on it.

 

[Aether2000]

Perhaps the mechanism of injury from a disc herniation is intraneural scarring that has been shown to occur rapidly after it occurs. Perhaps the mechanism of numbness and weakness is vasonervorum compression with subsequent spinal nerve edema and pain produced by DRG edema from the same mechanism....