radic screen

[topwise]

Apologies if this question isn't appropriate for this forum. I just had a question I was debating with someone today and I wanted to get the opinion of "the experts" .

What muscles do you test for your standard UE radic screen? Yes, I know you'd tailor it based on what is positive, but what muscles would you do to r/o radic? (And why?)

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[Ludicolo]

I like the root screen question, because there’s a couple of nice teaching points to be made here. I'll answer in two separate posts.

#1:
I would hazard a guess that most EMGers answering your question will give a list something like: FDI, FCR, biceps, triceps, deltoid. Dillingham’s article also provides a number of different muscle lists +/- paraspinals, all somewhat similar.

But standard screens are boring. Why not have a little fun w/ your EMGs? Consider this one: teres minor, coracobrachialis, supinator, palmaris longus, 4th lumbrical.

Students/residents: what’s the rationale in choosing this set of muscles?

 

[Ludicolo]

#2:
Consider the term “root screen”. I've always had a problem with that. A good screening test should be highly sensitive but not necessarily specific. EMGs have been shown to be specific, not necessarily sensitive. A true screening test checks for the presence of a given disease in asymptomatic patients. Asymptomatic patients are so not our referral population.

 

[topwise]

But standard screens are boring. Why not have a little fun w/ your EMGs? Consider this one: teres minor, coracobrachialis, supinator, palmaris longus, 4th lumbrical.

Students/residents: what's the rationale in choosing this set of muscles?

Because you're hoping to drop a lung?

OK, I like these games:
Teres minor: Axillary, C5-6
Corocobrachialis: Musculocutaneous, C5-7
Supinator: Radial, C5-6
Palmaris longus: Median, C7-8
4th lumbrical: Ulnar, C8-T1

So you've hit every nerve root from C5 to T1 as well as all the peripheral nerves. Just like the first standard "screen" you mentioned.

My standard "screen" (I'll use the quotes b/c I do agree with your other statement) is pretty much like the first one you mentioned, except substitute pronator teres for FCR. The argument I was having was over doing those five muscles PLUS the APB. The EMGer I was arguing with said that you had to do two C8-T1 muscles, but considering how rare T1 radics are, I really hate to stick a needle in that APB if I don't have to. I did it a lot yesterday and I didn't enjoy it.

P.S. I had an EMG case today that I'm dying to ask you about, but I don't want to post more than my quota...

 

[Ludicolo]

I'm nowhere near the lung with the lumbricals...

These muscles not only represent the all of the cervical roots/nerves, but also all of the trunks and cords, so they serve as a "plexus screen" as well.

Instead of the APB, try checking the opponens. Slide the needle just palmar to the 1st metacarpal. Seems to be less painful.

I agree, C8-T1 radics are fairly uncommon. Luckily, if you are suspicious for one there are many muscles you can check - APB, opponens, FPL, EIP...

 

[topwise]

I'm nowhere near the lung with the lumbricals...

Hmm... maybe I'm using too long a needle then?

So if you're doing a CTS study, do you check the opponens rather than the APB?

 

[PMR 4 MSK]

Hmm... maybe I'm using too long a needle then?

So if you're doing a CTS study, do you check the opponens rather than the APB?

I very often do - being more lateral, it's often a little less painful.

However, numerous times, I've needed all the median-innervated muscles of the thenar eminence and noticed significant variation in degree of denervation b/w the muscles.

 

[Ludicolo]

Hmm... maybe I'm using too long a needle then?

So if you're doing a CTS study, do you check the opponens rather than the APB?

Yes.

As PMR 4 MSK says, doesn't seem to hurt as much. Needle yourself and find out. I did as a resident, and I'll vouch for it.

Another school of thought regarding needling the opponens instead of the APB: you already evaluate the APB as part of your median motor NCS. May as well evaluate a different thenar muscle on EMG.

 

[topwise]

When I had a needle stuck in my APB, it hurt so much that I'm very hesitant to voluntarily attempt anything else in the vicinity....

(Yes, I am a wuss, but that's also why I don't like to do it to my patients. I've developed something called "empathy".)

PMR 4 MSK: Have you noticed that one particular muscle is more denervated than the others or is it totally random? Also, you didn't answer my question about your cervical radic screen!

 

[PMR 4 MSK]

When I had a needle stuck in my APB, it hurt so much that I'm very hesitant to voluntarily attempt anything else in the vicinity....

(Yes, I am a wuss, but that's also why I don't like to do it to my patients. I've developed something called "empathy".)

PMR 4 MSK: Have you noticed that one particular muscle is more denervated than the others or is it totally random? Also, you didn't answer my question about your cervical radic screen!

Interstingly, I notice the APB to be more atrophied - both on visual exam and needle. OP seems to show fibs and PSWs a little more when APB is neg, yet amplitude of APB NCS is quite low. I'll start keeping track and see what I find.

What didn't I answer?

 

[topwise]

What didn't I answer?

My original question about what muscles you'd test for a standard cervical radic screen.

 

[PMR 4 MSK]

My original question about what muscles you'd test for a standard cervical radic screen.

Hmm, wrote an answer, not sure where it went.

I do Delt, Tric, Bic, PT and FDIM - hits all major branches, all roots, several 2x.

 

[spondy14]

Apologies if this question isn't appropriate for this forum. I just had a question I was debating with someone today and I wanted to get the opinion of "the experts" .

What muscles do you test for your standard UE radic screen? Yes, I know you'd tailor it based on what is positive, but what muscles would you do to r/o radic? (And why?)

I go with deltoid, biceps, triceps, brachiorad (the books say a common C6, but I have yet to confirm this), PT and FDI. Stopped doing APB regularly (will do it with no median sensory, amplitude loss on median motor, just to confirm). For radic, bottom line is PSW's in PT = C6 and triceps = C7. Usually don't see much else in those cases. Also just had my first T1 radic, very interesting, of course looks and smells like an ulnar, the APB had the most denervation..good case.

 

[topwise]

I have an attending who I respect very much as an EMGer and he does brachioradialis over biceps because they're both C5-6 and BR seems to be less painful. I think that sounds reasonable to me, although nobody else seems to do that.

I guess the downside is that you're not getting a musculocutaneous muscle (you're still getting the lateral cord with the PT, right?) but that doesn't seem like it's such a big deal.