Ain

[PMR 4 MSK]

Shorter case, but interesting.

Pt tried to to pull the blankets back to his side of the bed in the middle of the night, felt a pop in his elbow/proximal forearm, about a month ago. Now he has difficulty bending the thumb IP joint. He can flex about 40 - 50 degrees, but with 3/5 strength. No numbness/tingling/paresthesias. Exam show just the thumb problem, normal strength, sensation and reflexes otherwise.

Median and ulnar motor and sensories were completely normal.

I tested the median nerve to the FPL, it had a distal latency of 5.1 (nl <3.6) and amplitude of 2.4 (nl > 3.8).

Needle exam normal for Delt, Bic, Tric, PT, FDIM and APB, but incresed insertional activity and 2+ fibs and PSW's in the FPL and PQ with decreased recruitment in those two, more so in the FPL. Motor unit morphology normal.

Dx - Anterior interosseous syndrome.

Could have needled the median-innervated FDP, but with ulnar-innervation of the other two and some variation, I don't rely on it.

If the EMG was negative, what would have been the most likely diagnosis?

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[Ludicolo]

You get some nice cases.

If the EMG was negative, what would have been the most likely diagnosis?

Come on guys/gals. Play the game. DDx of isolated thumb flexor weakness. Start with a broad differential. Think neurologic (peripheral and central) and non-neurologic. With a normal EMG - the differential shrinks.

 

[SSdoc33]

C8 radic, FPL strain/tear, median nerve injury (some wacky deep thenar branch?)

 

[PMR 4 MSK]

C8 radic, FPL strain/tear, median nerve injury (some wacky deep thenar branch?)

I wouldn't think C8 radic would be enough to give thumb weakness without needle findings.

FPL injury would be the more common injury, and should be #1 on the diff Dx.

 

[topwise]

I didn't make it to the board soon enough to answer this one, but I wanted to thank PMR 4 MSK for posting such interesting cases. I love EMGs.