Plexus Stretch lesion?

[latinman]

Young gentlemen who fell out of a moving vehicle and hit his shoulder first and then his neck (ie., bringing both apart). Pt noticed tingling for a 24-48 hours after the accident. The weakness in the right arm wasn't appreciated until almost a 12-14 months later. The subjective weakness was in the right forearm and hand. Everything in his forearm and hand would go numb. No neck pain was referred by the pt.

Physical Exam:
The AC joint was more prominent in the right shoulder. Hard to say whether there was some minor deltoid atrophy. However, suprapinatus in his right side look atrophied compared to his left shoulder blade. No winging of the scapula appreciated on either side.

Bilateral strength ok, except right brachioradialis in which pt would struggle. This guy was bulked up with a lot of muscle so it made it hard to appreciate any subtle weakness.

Reflexes: Decreased on Right Brachioradialis compared to left. Triceps symmetric. Biceps absent bilaterally.

Sensation Decreased on C5 on the right.

NCS Results:

Right and Left median recording to the thumb were within normal limitis. Less than 2 uV difference between each side. Pk Latencies were normal.

Right and Left radial recordings showed an amplitude difference greater than 50%. Latencies were fine.

Bilateral median to middle finger showed normal latencies and amplitudes side to side. No difference in amplitude.

Bilateral ulnar sensory studies showed normal amplitude and latency. There was a 33 % difference on amplitude side to side. The right ulnar amplitude was slightly lower. However, latencies were fine.

Bilateral LABC's showed an amplitude change of 37 % lower on the involved side (ie., right). The onset latency for this study is hard to define sometimes which makes comparing the amplitudes side to side a dicey call.

Bilateral ADM, APB and Deltoid CMAP's were within normal limits side to side.

Where do u guys think the problem is? I know needle EMG needed to be done, but because of timing constraints wasn't carried out.

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[RUOkie]

Talk to me once you go to where the money is (EMG). To even report a questionable plexus injury without EMG is worthless. (what kind of "timing constraints" caused you to stop a study midway?)

By history the patient has a upper trunk plexus injury (classic Erbs palsy). But when it comes to the brachial plexus and trauma, there is no such thing as typical.

So, needle a buttload of muscles and you will have your answer (or not, it could have been a stinger)

I would never make the call of a plexus injury based upon a low amplitude SNAP of LABC or even of a low amplitdue Radial SNAP. I use them as all or nothing responses.
Nor would I make the call based upon a 33% (but normal) Ulnar SNAP. There is too much normal variation to make that kind of call.

 

[DistantMets]

So far you've go 2 upper trunk SNAPs that are abnormal from different cords. You've got a possibly atrophied supraspinatus and a possibly weak brachioradialis with a depressed reflex. Sounds upper trunk, vs less likely C5/6 root, to me so far. I would see what the needle shows and consider doing a radial CMAP and more Erb's point CMAPs to the biceps and supra-/infraspinatus if you're not satisified and the patient is up for it.

 

[Ludicolo]

Clinically, sounds like a prior upper trunk injury secondary to trauma. But maybe I’m missing something here. He didn’t notice weakness until a year later? And his subjective weakness was in the hand, yet his atrophy was more proximal. Odd.

Electrodiagnostically, based on your findings, my impression would read: “abnormal nerve conduction studies”. I would call the radial sensory amplitude abnormal, given the 50% side-to-side difference. Can’t/wouldn’t say anything else. Agree w/ RUOkie, you need to correlate NCS findings w/ the EMG findings.

So let's play the game OP. What would you check on needle exam? (and the answer "a buttload" has already been given ).

 

[PMR 4 MSK]

Bilateral LABC's showed an amplitude change of 37 % lower on the involved side (ie., right). The onset latency for this study is hard to define sometimes which makes comparing the amplitudes side to side a dicey call.

You're using Onset for sensory? Peak latency with P-T amplitude is easy to compare.

 

[RUOkie]

So let's play the game OP. What would you check on needle exam? (and the answer "a buttload" has already been given ).

He sent me a PM with that info--He had very good choices.

You're using Onset for sensory? Peak latency with P-T amplitude is easy to compare.

Good pickup there, I did not even notice that he said onset latency. I agree completely that peak latency is much easier to use for SNAP

 

[latinman]

For the latencies I am using onset and peaks. I see what u mean. Put the marker at the peak and when it comes back to baseline. Makes sense, I will try that and come back and let u guyz know.

Anyway, muscles I would have considered for EMG:

Upper Trunk: Supraspinatus, Deltoid, Brachioradialis, and Biceps.
Lateral Cord: Biceps, and Pronator Teres vs. FCR.
Middle Trunk: Triceps, and Pronator Teres.
Posterior Cord: Triceps, or Brachioradialis, and Deltoid.

Lower trunk (Less likely to be the cause): EIP, FCU, FPL, and APB.

Medial Cord: Same as LT, but EIP is clean.

Also, Ruokie told me about Serratus Anterior and Rhomboids; They are good muscles, but I seem a little nervous with poking needle into both of them because of PTX. I know that for the Serratus anterior if you go above the rib the likelihood of this happening is low.

 

[latinman]

So I switched the markers, and it actually made the difference between the LABCs side to side smaller. Probably this is hurting me if I am thinking of plexopathy. Needle will have to be done in this pt.

 

[RUOkie]

but I seem a little nervous with poking needle into both of them because of PTX. I know that for the Serratus anterior if you go above the rib the likelihood of this happening is low.

Off topic: The first time I stuck Serratus as a resident (back when we used 24G needles (ouch)), I had been married for 1 week. I was sweating, and a little shakey. My staff was talking me through it and then as I was breaking the skin, my pager went off. It was my wife calling to ask when I would be getting home We laughed a lot!

If you keep your fingers in the interspace of the ribs, insert the needle until you hit bone and pull back a few mm. You will never drop the lung. So long as you prepare the pt. that it will hurt.

Rhomboids are a little tougher, but very safe. Just keep your emg running live during insertion so you know when you leave the trapezius and enter the rhomboid.

Keep Perotto nearby! Read it before bed! The needle localization tricks they have make it so much easier to find the tough muscles. (Like FPL for instance)

 

[latinman]

I like all the great advice I get in these forums. I promise to keep posting good and interesting cases.

 

[Ludicolo]

Decent muscle choices. The serratus and rhomboids are muscles all residents should learn how to stick safely under supervision. Had a residency mate think it was a good idea to check the rhomboids without telling the attending. Patient ended up with a chest tube an hour after EMG exam. Know your landmarks, and know how to activate each muscle (i.e. the rhomboids vs. the traps) so you know you’re actually in the correct muscles. For the serratus, have your fingers border the rib, slide the needle between your fingers along the rib, just anterior to the border of the latissimus. If you hear respiratory muscle patterns – don’t advance the needle. Your buffed out patient should have excellent surface anatomy to practice on.

Perotto rocks. I read it to sleep every night during my EMG rotation. Wife thought I was nuts.

 

[PMR 4 MSK]

Decent muscle choices. The serratus and rhomboids are muscles all residents should learn how to stick safely under supervision. Had a residency mate think it was a good idea to check the rhomboids without telling the attending. Patient ended up with a chest tube an hour after EMG exam. Know your landmarks, and know how to activate each muscle (i.e. the rhomboids vs. the traps) so you know you’re actually in the correct muscles. For the serratus, have your fingers border the rib, slide the needle between your fingers along the rib, just anterior to the border of the latissimus. If you hear respiratory muscle patterns – don’t advance the needle. Your buffed out patient should have excellent surface anatomy to practice on.

Perotto rocks. I read it to sleep every night during my EMG rotation. Wife thought I was nuts.

My first and only dropped lung was attempting to botox serratus anterior under supervision, with EMG guidance. Pt left, came back 20 min later dyspnic. Got xray and had small pneumothorax. Nurse took him down to the ER - they watched him for a few hours and it re-inflated, no tube needed.

Teaches you humility and caution, it does.