Route of regeneration of median branch nerve after RFA

[caligas]

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Can anyone enlighten me on where the median branch nerve regenerates after serial RFA? Is it possible that the new route can be aberrant from original location to the degree that it prevents successful future RFA?

If so, how can this be managed?

Thanks

 

[Baron Samedi]

Current ablation techniques disrupt the axon and myelin but do not disrupt the perineurium, epineurium, or fascicular arrangement of nerves. We are producing Sunderland type 3 peripheral nerve injuries. The route of regeneration should be along its original pathway.

 

[BobBarker]

I had a saphenous vein ablation around 13 years ago. After the procedure, really profound numbness for over a month. Saphenous nerve also got ablated. “It will come back. Don’t worry.” Well, I do have some hyperalgesia to tapping but that is about it. But my socks and shoes don’t bother me so I’m fine. In this case, it really hasn’t come back at all. Larger diameter nerve so not apples to apples but still something anecdotal to add to the discussion.

 

[cowboydoc]

Can anyone enlighten me on where the median branch nerve regenerates after serial RFA? Is it possible that the new route can be aberrant from original location to the degree that it prevents successful future RFA?

If so, how can this be managed?

Thanks

I have speculated a more tortuous “wide turn” may occur with reinnervation.

I need to look into Baron’s claim of degree of nerve damage with our ablation techniques…If true, the nerve regeneration should follow inside the perineurium and maintain the original course. If the perineurium is damaged, the regenerating fibers are blindly feeling through the dark, perhaps with the assistance of cellular signals. One must also consider the perineurium may degrade over time, even if not damaged with the initial insult (thermal injury in this case). Could some find their way back to the joint in this manner? Perhaps.

In vitro nerve behavior and in vivo situations after ablation takes some speculative leaps. I don’t think we know for sure regarding many factors the reasonable question being proposed involves.

Practically, I will perform a larger lesion on a repeat ablation to decrease likelihood of missing straggler fibers. Also, I will occasionally have home runs with ablations and the repeat just doesn’t wok, and the updated MRI post ablation is not revealing. Quien sabe???

Some would consider an endoscopic medial branch neurotomy in a situation like this, but this is not in my purview at this time.

 

[pastafan]

Current ablation techniques disrupt the axon and myelin but do not disrupt the perineurium, epineurium, or fascicular arrangement of nerves. We are producing Sunderland type 3 peripheral nerve injuries. The route of regeneration should be along its original pathway.View attachment 397479

What about the possibility of physical disruption caused by needle placement? I suspect that some especially long lasting RFA results occur due to this mechanism.

 

[Baron Samedi]

What about the possibility of physical disruption caused by needle placement? I suspect that some especially long lasting RFA results occur due to this mechanism.

I think that would be very low on my ddx for a failed repeat RFA.

For me I'd think about probe placement, progressive disease, MAL ossification, alternative diagnosis, crazy patient long before I thought about that.

 

[SgtThunderfistMD]

I have speculated a more tortuous “wide turn” may occur with reinnervation.

I need to look into Baron’s claim of degree of nerve damage with our ablation techniques…If true, the nerve regeneration should follow inside the perineurium and maintain the original course. If the perineurium is damaged, the regenerating fibers are blindly feeling through the dark, perhaps with the assistance of cellular signals. One must also consider the perineurium may degrade over time, even if not damaged with the initial insult (thermal injury in this case). Could some find their way back to the joint in this manner? Perhaps.

In vitro nerve behavior and in vivo situations after ablation takes some speculative leaps. I don’t think we know for sure regarding many factors the reasonable question being proposed involves.

Practically, I will perform a larger lesion on a repeat ablation to decrease likelihood of missing straggler fibers. Also, I will occasionally have home runs with ablations and the repeat just doesn’t wok, and the updated MRI post ablation is not revealing. Quien sabe???

Some would consider an endoscopic medial branch neurotomy in a situation like this, but this is not in my purview at this time.

I have seen a video of the procedure at a course, but who actually does this that you would refer out to?

 

[soccrwz]

I have seen a video of the procedure at a course, but who actually does this that you would refer out to?

I do

 

[cowboydoc]

I have seen a video of the procedure at a course, but who actually does this that you would refer out to?

Talk on this site and muttering from arthrex is my familiarity with the endoscopic tx. The presented situation is the only one I see a role for endoscopic approach at this point.

I think that would be very low on my ddx for a failed repeat RFA.

For me I'd think about probe placement, progressive disease, MAL ossification, alternative diagnosis, crazy patient long before I thought about that.

Good ddx in general. I think the OP is asking for personal reasons, seems pretty objective, and in a tough spot.

 

[caligas]

Talk on this site and muttering from arthrex is my familiarity with the endoscopic tx. The presented situation is the only one I see a role for endoscopic approach at this point.

Good ddx in general. I think the OP is asking for personal reasons, seems pretty objective, and in a tough spot.

Correct. Worked 4 times and then didn’t. Exact same symptoms and treatment.

 

[swamprat]

I'ver done endoscopic rhizotomy (although don't call it that or ewill be denied by payors). Works much faster than needle RFA and I've gotten over 2+ years for patients - possible because this is a fully transected nerve over a larger area. Highly recommend this procedure for patients with good but short term relief with traditional needle rhizotomy.

 

[Ducttape]

previously, when chemical neurolysis was used, apparently there was a lot of what was considered scar neuroma neuritis due to the chemical destruction of the medial branch. hence use of RFA which does not destroy the epineurium.

this also occurred with cryoablation (the old probes), if not allowed to warm up, would pull out a nice big chunk of "flesh" with it.

i would wonder about the incidence of this with endoscopic rhizotomy, as the nerve is again severed. maybe because such a long segment is taken out, it doesnt occur?

otoh, it would make sense to try this for those who had chemical neurolysis that failed, as the entire neuroma could be resected.

 

[swamprat]

previously, when chemical neurolysis was used, apparently there was a lot of what was considered scar neuroma neuritis due to the chemical destruction of the medial branch. hence use of RFA which does not destroy the epineurium.

this also occurred with cryoablation (the old probes), if not allowed to warm up, would pull out a nice big chunk of "flesh" with it.

i would wonder about the incidence of this with endoscopic rhizotomy, as the nerve is again severed. maybe because such a long segment is taken out, it doesnt occur?

otoh, it would make sense to try this for those who had chemical neurolysis that failed, as the entire neuroma could be resected.

Yeah I clinically haven't seen any post-operative neuritis after endoscopic rhizotomy - perhaps due to the large amount of nerve transected neuromas don't form or if they do they don't bother the patient compared to the relief they get from their axial back pain.

 

[soccrwz]

I haven't seen post operative neuritis after endoscopic rhizotomy either