wrist drop after GSW

[PMR 4 MSK]

Had a 16 year in for EMG yesterday, GSW right arm 4 weeks ago, wrist drop now. Bullet entered the right arm laterally about and inch or two above the lateral epicondyle and exited from the anteromedial forearm about 1/3 distal from the elbow. No fractures, clean through-and-through. Wounds are healed/closed, no signs infx.

He also interestingly has a flexion contracture of the elbow at 90 degrees. Cannot extend pasive or actively. Elbow flexors are soft and pliable, don't feel spastic. No Hx neck or head injury. Normal reflexes including Hoffman's.

Exam shows no extension of the wrist or fingers, weakness of grip due to loss of extension (power grip), paresthesias in the radial sensory distribution.

Median motor had normal distal onset 3.3 mildly low amplitude 4.6 mV, distal NCV 46 m/s, upper arm 66 m/s. Median sensory normal peak latency (3.1), amplitude (60 mcV) and NCV (61m/s). F-waves normal.

Ulnar motor normal onset (2.9), amplitudes (6.5) and NCV's (50's BE and across elbow). Ulnar sensory similarly normal and F-waves normal.

Radial motor showed distal onset of forearm to EIP of 6.1 (nl < 2.8), amplitude 0.3 mV and no response at the elbow or above. Radial sensory to first dorsal webspace got a consistent waveform at 7.9 ms peak latency (nl < 3.1) and amplitude 16 (nl > 10), but I'm not entirely convinced it was the sensory response, as it took 100 mA stim at 250 mS. No proximal response. Radial F-waves were absent.

Also did Erb's point stim to the right bicep, tricep and deltoid, all with normal onsets and amplitudes.

Needle exam showed normal IA, no spontaneous waves, normal motor units of the right deltoid, lateral triceps, biceps, pronator teres, FDIM and APB. EDC and EIP both showed 3+ PSW and fibs, no motor voluntary acitivity.

So he's got a severe radial nerve lesion below the triceps, motor and sensory, a mild axonal median nerve injury, and an elbow contracture all after GSW.

What would you do for him?

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[SSdoc33]

Had a 16 year in for EMG yesterday, GSW right arm 4 weeks ago, wrist drop now. Bullet entered the right arm laterally about and inch or two above the lateral epicondyle and exited from the anteromedial forearm about 1/3 distal from the elbow. No fractures, clean through-and-through. Wounds are healed/closed, no signs infx.

He also interestingly has a flexion contracture of the elbow at 90 degrees. Cannot extend pasive or actively. Elbow flexors are soft and pliable, don't feel spastic. No Hx neck or head injury. Normal reflexes including Hoffman's.

Exam shows no extension of the wrist or fingers, weakness of grip due to loss of extension (power grip), paresthesias in the radial sensory distribution.

Median motor had normal distal onset 3.3 mildly low amplitude 4.6 mV, distal NCV 46 m/s, upper arm 66 m/s. Median sensory normal peak latency (3.1), amplitude (60 mcV) and NCV (61m/s). F-waves normal.

Ulnar motor normal onset (2.9), amplitudes (6.5) and NCV's (50's BE and across elbow). Ulnar sensory similarly normal and F-waves normal.

Radial motor showed distal onset of forearm to EIP of 6.1 (nl < 2.8), amplitude 0.3 mV and no response at the elbow or above. Radial sensory to first dorsal webspace got a consistent waveform at 7.9 ms peak latency (nl < 3.1) and amplitude 16 (nl > 10), but I'm not entirely convinced it was the sensory response, as it took 100 mA stim at 250 mS. No proximal response. Radial F-waves were absent.

Also did Erb's point stim to the right bicep, tricep and deltoid, all with normal onsets and amplitudes.

Needle exam showed normal IA, no spontaneous waves, normal motor units of the right deltoid, lateral triceps, biceps, pronator teres, FDIM and APB. EDC and EIP both showed 3+ PSW and fibs, no motor voluntary acitivity.

So he's got a severe radial nerve lesion below the triceps, motor and sensory, a mild axonal median nerve injury, and an elbow contracture all after GSW.

What would you do for him?

great post. this is always the question: what to do with a peripheral nerve injury. in this case, we have a clear cut, most likely complete, radial nerve lesion in a young, healthy patient at 4 weeks. there is literature on this subject in the neurosurgery community, but i think that it is equivocal at best. outcomes are sometimes worse than if you do nothing. the question then becomes, do you have a surgeon take a look, do a nerve debridement, possible nerve graft? if so, how long do you wait.

i think in this case, you give it some time. assuming the location above, you are talking about only a few inches for axonal regrowth to reach some of the wrist extensors. if we are talking an inch a month, then you would hopefully see some voluntary activity a couple months out.

id have him come back in 1 month, then look for voluntary activity via EMG at the most proximally innervated radial muscle distal to the lesion (?ECRB? not exactly sure which muscle). if there's nothing going on, id move him on to a surgeon to be evaluated. wait too long and the muscles atrophy, and you wont get a good outcome with any nerve surgery.

not quite sure what to make of the elbow flexion contracture. ? scar in antecubital fossa. if the triceps works, that should get back to near normal in PT/OT

id love to hear the latest neurosurg opinion on this if there's anybody who has info on it......

 

[Disciple]

I'd at least get a surgical consultation.

The fact that there is no voluntary motor activity on needle exam is concerning.

The muscle isn't going to reinervate if the nerve is transected.

Here's a thought, musculoskeletal ultrasound to see if the epineurium is intact?

 

[SSdoc33]

I'd at least get a surgical consultation.

The fact that there is no voluntary motor activity on needle exam is concerning.

The muscle isn't going to reinervate if the nerve is transected.

Here's a thought, musculoskeletal ultrasound to see if the epineurium is intact?

MSK U/S is a good idea to assess for nerve contiuity.

The muscle may not re-innervate with a nerve graft, either. may get some collateral sprouting, though.

I don' think you could be faulted by referring the patient to a surgeon. but i feel like when ive made that step, i have essentially given my "ok" for the surgeon to cut. its like referring a low back patient to a surgeon when i REALLY dont think they should have surgery. doesnt sit well with me, and i feel some guilt even though im not the one doing the surgery.