Post op nerve injury

[RUOkie]

Got a call from an anesthesiologist last evening asking me to see someone urgently. Luckily I was still in the hospital.

(residents/med students, this is what you build your reputation for, and why you jump to it when you are called. You may not be taking ER call, but you go see people quickly if you are asked)

54 year old female with severe, post traumatic OA of the wrist admitted to Same day surgery for an elective wrist arthrodesis. Ortho did a dorsal approach to the radiocarpal joint and performed a wrist arthrodesis with BMP and a Synthes plate. Tourniquet time was 2 hrs at 250mmHg. Anesthesia attempeted an Axillary block with 15cc Lidocaine and 15cc Bupivicaine. They reported the block as "unsucessfull" and then induced for GET.

On awakening, the pt. had severe hyperesthsia/pain of the entire hand, with near total anesthesia of the Median, Ulnar, DUC Nerves and partial anesthesia of the radial nerve. She also had SOB, and was admitted. Initially this was thought to be a prolonged anesthetic response.

20hrs post op, the L hand was still numb/painful with impaired motor function of the hand. Anesthesia was called, they called me to evaluate.

Her PMHx is significant for COPD (quit smoking 2 months ago after a 60pack-yr history), L CTS release (>10yrs ago), and Bilateral first rib removals for TOS 30+ yrs ago. As well as a L wrist fx with malunion which led to the severe OA of the wrist.

On my exam she had 0/5 Median, 0/5 AIN, 0/5 Ulnar (could not test any wrist flexors/extensors for obvious reasons), and 0/5 Finger Extensors. Her Brachioradialis was 0/5. Biceps, Triceps and ALL other proximal muscles were 5/5. She had some sensation in all areas but was severely hyperpathic in Median, Ulnar, dorsal ulnar cutaneous and Superficial Radial N. distributions. She had altered (but not hypterpathic) sensation in the MABC nerve. LABC and all other proximal sensory nerves were normal.

I started Lyrica last night, advised her in gentle ROM of the fingers and returned this AM. Exam was unchanged except she now has a flicker of movement in the finger extensors and her sensation in the Superficial Radial N. was now normal. MABC sensation was also better.



OK. What the heck caused this? She is set up to f/u with me in 2 weeks, and if still weak I will do the EMG then.

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[PMR 4 MSK]

Sounds like a tourniquet pressure and/or ischemic injury to all distal nerves.

Reassurance to her that this will likely resolve could help.

 

[Ludicolo]

Agree that proximal upper extremity neurapraxic/compression injury is the most likely culprit. Only thing that would hit multiple peripheral nerves (median, ulnar, post-spiral groove radial, MABC) with sparing of the musculocutaneous and axillary nerves. This isn’t coming from the plexus or roots. But some thoughts…

When you say 0/5 median motor: does this include pronator teres? That would make for a convincing proximal median nerve injury. Or could you not test pronation 2ndary to the surgery?

Did she have any pre-morbid deficits stemming from her prior CTS, TOS hx/surgeries? I also agree that this should improve with time, but prior hits to her nerves might make for a more prolonged recovery, although early return of the MABC and radial nerve is encouraging.

 

[fozzy40]

Would also be nice if she has a good baseline post-CTS EMG/NCV. Should be a great exam! Keep us posted.

 

[RUOkie]

Agree that proximal upper extremity neurapraxic/compression injury is the most likely culprit. Only thing that would hit multiple peripheral nerves (median, ulnar, post-spiral groove radial, MABC) with sparing of the musculocutaneous and axillary nerves. This isn’t coming from the plexus or roots. But some thoughts…

When you say 0/5 median motor: does this include pronator teres? That would make for a convincing proximal median nerve injury. Or could you not test pronation 2ndary to the surgery?

Did she have any pre-morbid deficits stemming from her prior CTS, TOS hx/surgeries? I also agree that this should improve with time, but prior hits to her nerves might make for a more prolonged recovery, although early return of the MABC and radial nerve is encouraging.

I really could not test it well, but it "appeared" to be gone. We encouraged her. I'll update in 2 weeks

 

[RUOkie]

Would also be nice if she has a good baseline post-CTS EMG/NCV. Should be a great exam! Keep us posted.

It sure would. But you NEVER get that.

As Mick said, "you can't always get what you want..."

 

[SSdoc33]

i also agree that the tourniquet is the most likely culprit. however, if you really want to dig deep, find out exactly what the anesthesiologists did. 30 mL is a lot of volume is a relatively small space. i have seen several brachial plexopathies after peripheral procedures (mostly interscalene blocks). many anesthesiologists dont use u/s and just stick the needle where they think it should go. you can easily get an intra-neural injection this way.

on the plus side, i would think that if ideed the weakness is due to tourniquet compression, this may come back better than a true neurotmetic injury

 

[RUOkie]

Saw the lady in the office today. We scheduled time for an EMG since last week the orthpod called saying she was still numb and week.

On exam she had trace finger extension, 5/5 brachiorad, trace ABP, and 0/5 in the ulnar. Now with impaired Median sensation, anethesia in the Ulnar and normal elsewhere.

So we did the EMG.--If anyone has ever done a study on a pt. who is 2wks postop from a wrist fusion or ORIF, you know that these are difficult because of postioning. Also, Ground placement was a challenge because of the location of her incision.

Low Amplitude CMAP (2mv) Median and Ulnar motor with normal distal latency and NCV.

Normal Median and Sup. Radial SNAP.

Unobtainable Ulnar SNAP.

I was unable to even attempt F-waves (I said this was a tough study)

EMG showed NORMAL insertional and rest activtiy in all muscles.

She had no voluntary MUAP in FDI, but had 50% recruitment in ADM (she needed the muscle to be passively moved first and then she used the sound of the EMG as feedback)

APB and the finger extensors and flexors had 75% recruitment. The remainder of the study was normal.

So, this was a neuropraxic injury, location unknown. After a lot of reading, I am leaning toward the Medial and Posterior cords as the site of damage. Her tourniquet time was only 2 hrs at 200mmHg. Dumitru has a good write up on Tourniquet injuries, and this was not enough time to directly injure the nerves without a compartment syndrome (which she did not have).

 

[Ludicolo]

Thanks for the update. Nice work.

Technically challenging study to be sure. Post-op patient positioning persistently problematic . Were median and ulnar motor amplitudes reduced both proximally and distally? Did you stimulate above the tourniquet site (axilla or Erbs)? Did you check antebrachials? Were MUPs normal size/morphology?

The NCS findings of low amplitude median and ulnar motors, in the setting of a low amplitude ulnar sensory and a NORMAL median sensory response, is almost pathognomonic for lower trunk/medial cord plexopathy. Not sure if you can say posterior cord, given normal radial SNAP. Finger extensors, though radial nerve/posterior cord innervated, generally have some lower trunk/C8 involvement. So given your EDX findings, I vote lower trunk.

IIRC: your lady had a h/o TOS + rib removal, which may have caused prior insult to the lower trunk/medial cord. And she had a h/o CTS surgery, where (depending on the initial severity of the CTS) you can see normalization of the median CMAP distal latency but residual low amplitude motor amplitude. But if this were the case, I would’ve expected to see abnormalities in the median SNAP as well. Also not sure why she has impaired sensation in the median nerve distribution, if her median SNAP was normal.

Her prior neuromuscular history complicates things a bit – and it underscores the importance/benefit of having a baseline EMG for comparison (yeah I know. But if you try sometimes, you get what you need ).

 

[RUOkie]

Thanks for the update. Nice work.

Technically challenging study to be sure. Post-op patient positioning persistently problematic . Were median and ulnar motor amplitudes reduced both proximally and distally? yes
Did you stimulate above the tourniquet site (axilla or Erbs)? no
Did you check antebrachials? no but her sensation was now normal in both Were MUPs normal size/morphology? yes

The NCS findings of low amplitude median and ulnar motors, in the setting of a low amplitude ulnar sensory and a NORMAL median sensory response, is almost pathognomonic for lower trunk/medial cord plexopathy. Not sure if you can say posterior cord, given normal radial SNAP. Finger extensors, though radial nerve/posterior cord innervated, generally have some lower trunk/C8 involvement. So given your EDX findings, I vote lower trunk.

IIRC: your lady had a h/o TOS + rib removal, which may have caused prior insult to the lower trunk/medial cord. And she had a h/o CTS surgery, where (depending on the initial severity of the CTS) you can see normalization of the median CMAP distal latency but residual low amplitude motor amplitude. But if this were the case, I would’ve expected to see abnormalities in the median SNAP as well. Also not sure why she has impaired sensation in the median nerve distribution, if her median SNAP was normal. that there is the kicker. I suspect that the initial insult was more diffuse. now her sensation is present but impaired.

Her prior neuromuscular history complicates things a bit – and it underscores the importance/benefit of having a baseline EMG for comparison (yeah I know. But if you try sometimes, you get what you need ).

This overall was a challenge. I consider myself a pretty good electromyographer. I do 600+/yr for the past 14yrs. And still things stump you. That is why it is called a practice.

Thanks for the critique. I never think about the finger extensors being lower trunk, but you are right. They are partially innervated by the lower trunk, posterior division, posterior cord. The problem there is that the block was an axillary block (post-clavicular) which puts you at the level of the cords/branches not the trunk. Unless of course the anatomy was changed by the previous surgery.

 

[SSdoc33]

good case. the brachial plexus studies always make you think. its refreshing actually, rather than always doing your typical CTS screen aor radiculopathies.

dollars to donuts the anesthesiologist whacked the plexus. looks like she should mostly recover, however.