MEPs

[Multifidus]

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Where I trained, motor evoked potential monitoring was accomplished just fine with 2/4 twitches.

Fast forward to present day, new PP gig. The audiologist is monitoring motors and says I cannot use any muscle relaxant. I kindly question this statement, explaining that where I trained we routinely monitored motors with 2/4 twitches. This audiologist refuses to believe that motors could possibly be monitored with any neuromuscular blockade.

I realize many people monitor MEPs without any relaxant. Heck, that is how most textbooks teach the subject. I'm just curious how the hell some places get by just fine with some neuromuscular blockade and how some people (like the audiologist I worked with) think it is IMPOSSIBLE. I can see that monitoring would perhaps be better with no blockade, but it isn't impossible, is it? If so, my training hospital was a fraud.

I would love to hear about this issue from any neurophysiologists, audiologist, or anesthesiologists that know this subject well.

 

[Trisomy13]

Where I trained, motor evoked potential monitoring was accomplished just fine with 2/4 twitches.

Fast forward to present day, new PP gig. The audiologist is monitoring motors and says I cannot use any muscle relaxant. I kindly question this statement, explaining that where I trained we routinely monitored motors with 2/4 twitches. This audiologist refuses to believe that motors could possibly be monitored with any neuromuscular blockade.

I realize many people monitor MEPs without any relaxant. Heck, that is how most textbooks teach the subject. I'm just curious how the hell some places get by just fine with some neuromuscular blockade and how some people (like the audiologist I worked with) think it is IMPOSSIBLE. I can see that monitoring would perhaps be better with no blockade, but it isn't impossible, is it? If so, my training hospital was a fraud.

I would love to hear about this issue from any neurophysiologists, audiologist, or anesthesiologists that know this subject well.

I had a similar situation with our neurophys monitor insisting that ANY volatile agent would abolish his SSEP and it needed to be a strict TIVA, whereas we regularly ran about 0.4-0.6 MAC desflurane in our monitored cases "back home" in training, with good feedback from our neuro guys.

I at least convinced him to not stick the damn pin right where my art line was going to be

 

[Multifidus]

What annoys me about this situation is I can't figure out of this neuromonitoring person is either

A. completely misinformed and poorly educated in his field of expertise and actually thinks it is downright IMPOSSIBLE to monitor any form of MEPs with ANY degree of neuromuscular blockade

or

B. thinks I am completely ignorant and it is just easier for him to tell me that is impossible to monitor MEPs with blockade rather than have a brief discussion about how his monitoring of MEPs is immensely improved without of blockade, but no, not completely impossible.

If you are going try to call yourself a "doctor" of audiology, you better be knowledgeable in your field, know the various ways of performing your specialty (including those that you may not be accustomed to), and, most importantly, be prepared to truthfully and professionally discuss the reasons for the way you do your job.

End rant.

 

[scotchnwater]

Multifidus -

What kinds of cases are you doing? Is the pt in Mayfield pins or you otherwise have a specific reason you need them paralyzed?

How are the neuromonitors going to differentiate a loss or degradation of signal that comes from your NMB from that of surgical etiology - unless you can somehow guarantee a steady-state of NMB that will be unchanged for the duration of their monitoring? At the very least using NMB decreases the specificity of their monitoring.

We have one of the largest spine programs in the country, and almost each and every case is done with neuromonitoring, and I have never seen or heard of running a case WITH NMB beyond a small intubating dose.

Also, why is an audiologist doing this......aren't there training programs specifically for neuromonitoring?

 

[proman]

MEPs alone, I would typically do a NMB infusion targeting 3 twitches by their sensors. If hypothermia was involved I wouldn't do any NMB after intubation.

SSEPs do better at 0 twitches. Less than 1 MAC of volatile anesthetic does not hinder the quality of their signals. The key is to set your anesthetic prior to their baseline and not adjust it. And turn off the MAC display on the monitor.

MEPs + SSEP would get an infusion targeting 2 twitches. Again, if hypothermia was planned I would avoid NMB.

EEG is extremely sensitive to volatile anesthetics, so I would do TIVA. I've found it next to impossible to discuss rational anesthetic use with neurophysiologists. The supervising neurologists are more reasonable. How is an audiologist qualified at all to interpret anything other than auditory evoked potentials?

 

[Multifidus]

Multifidus -

What kinds of cases are you doing? Is the pt in Mayfield pins or you otherwise have a specific reason you need them paralyzed?

How are the neuromonitors going to differentiate a loss or degradation of signal that comes from your NMB from that of surgical etiology - unless you can somehow guarantee a steady-state of NMB that will be unchanged for the duration of their monitoring? At the very least using NMB decreases the specificity of their monitoring.

We have one of the largest spine programs in the country, and almost each and every case is done with neuromonitoring, and I have never seen or heard of running a case WITH NMB beyond a small intubating dose.

Also, why is an audiologist doing this......aren't there training programs specifically for neuromonitoring?

I'm talking about spine cases as well. I didn't have to have the patient paralyzed. I was just trying to have a discussion with the neuromonitoring person about why I had been able to do many, many similar cases with some degree of neuromuscular blockade at my previous institution.

In terms of you question, I would typically run a vec infusion and have a fairly constant level of blockade. Close communication with my previous neurmonitoring people would ensure I didn't give a small bolus of vec close to a crucial monitoring time for them. Nonetheless, they were able to monitor just fine with some degree of relaxation. It wasn't just me, we did A LOT of neuro and spine at my program as well.

As far as the audiologist thing, beats me. It was the first I had heard of it as well.

 

[jwk]

I want to know from the neuro TECHS "what would you LIKE me to do?" Then I can tell you what I CAN or am WILLING to do. I'm not stupid - I'll work with you, but communication is key.

I assume everyone is at least going to get some roc for intubation. As soon as the patient gets flipped and the needles/pads are applied, it's time for them to be checking signals. Roc is still on board and I've got one MAC of agent still running and you've got good signals? Great, we'll be fine. Things aren't what you like? Fine, I'll see what I can do as I move from induction drugs to maintenance drugs, and I'll bet by the time we get to a few minutes past incision, everyone will be happy.

Most of our neuro techs are fairly reasonable. Those that aren't? Easy - I simply tell the surgeon that he needs to understand his patient will be moving at random times during the procedure. That usually solves the problem.

 

[epidural man]

hard to keep 2 twitches - or a constant serum level - unless running an infusion with nimbex (...i love nimbex...)

But all I know is my monitoring folks love me cuz I always use ketamine - and they love the signal boost i give them.

 

[sevoflurane]

hard to keep 2 twitches - or a constant serum level - unless running an infusion with nimbex (...i love nimbex...)

But all I know is my monitoring folks love me cuz I always use ketamine - and they love the signal boost i give them.

Yep and BIG Yep.

👍

 

[MTGas2B]

When it comes to TIVA and neuromonitoring cases, I like to add a dexmedetomidine infusion. I use it to reduce the propofol dose. It dosen't really have any effect on signals. I like it at the end for wake up too.

Where I usually work no one seems to care about the cost, so we can use it as much as we want.