Q: how to diagnose compartment syndrome with emg?

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15+ Year Member
Apr 6, 2007
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I'm not asking about any specific compartment, and hopefully some kind physicians can explain one/or all of them.

I was told that there are specific muscles that affected the most in each compartment, but not which ones.

did a google search which was unsuccessful. any explanation/answers would be greatly appreciated.

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For EMG cases, I love the archives on the AAPM&R website (there are also good msk cases):


Case #71 is a good case of compartment syndrome (in my humble resident opinion), which goes through an EMG case with an explanation at the end.
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Compartment syndrome can only truly be diagnosed with a pressure gauge. There are times that the clinical picture +/- EMG can suggest compartment syndrome, but the EMG cannot make the diagnosis.

For example. A patient comes to you with 3 weeks of numbness in the Median distribution with weakness in the Median and AIN (anterior interosseous) muscles. This presents on awakening from a 12 hour tumor resection with a blood pressure cuff on that arm, and both arms tied down with a sheet during the case. The OR notes do not document releasing the pressure for the entire 12 hours. When the patient awakes, he cannot straighten that arm and his antecubital fossa is red and swollen (it goes down in 2 days). What is the diagnosis? It is likely compartment syndrome, but the abnormal electrodiagnostics only confirm the diagnosis.

If you read Dumitru in the sections on peripheral nerve entrapments, you will see compartment syndrome mentioned in the etiology of multiple upper extremity and lower extremity focal neuropathies. This holds true for exercise induced compartment syndrome as well. If you have the neuropathy, you still need the exercise stress test with the pressure gauge to make the diagnosis (you don't want to do a faciotomy without it!)

It is important to know your anatomy really well, the diagnosis is easy.
Maybe this is where my EM background comes in handy.

If a patient presents with new onset rest pain, pain on movement, paresis/paralysis, and pain on passive flexion/extension on exam, I'm done, I've made the diagnosis, +/- history (there are folk with CS who just aren't very clear about what's been going on in their lives lately so this component has to be optional), +/- edema, +/- erythema, I call a surgeon, I get a Stryker (R), in that order, and make measurements, usually when the surgeon arrives to do the pokes once, takes just a couple of minutes. I might now muck around with other w/u, investigations, history, and pre-op orders.

I don't believe I have missed or misdiagnosed any compartment syndromes I've seen here in Detroit.

Fasciotomies work, but only if you get it done sonner rather than later, with few complications, , and if done soon enough, at least limitation of progression, and if done even earlier in the course, with restoration of function.

So, the goal is to rule out the need for a fasciotomy, NOT try to avoid a fasciotomy.

As suppose it may become a more complicated diagnostic process in the picture of spinal cord or other nerve injury with coincident anesthesia. There I would think it's history of mechanism, +/- exam, intracompartmental pressure measurement on clinical suspiscion.

If the goal is to prevent ischemic contracture then as with acute myocardial infarction, time is muscle.