No activation on EMG?

    • July 26, 2017 at 5:38 pm

      Just out of curiosity… I was looking over my husband’s EMG report from January 2016. It states that “motor unit potentials could not be assessed in the vastus medialis due to no activation.” Are there any doctors or nurses who could explain why that’s not clinically significant?

    • jk
      July 27, 2017 at 11:58 am

      I have no recollection of a medical professional actively participating on this Forum in any meaningful way. Irrelevant, I guess. Now, a due diligence disclaimer, I am definitely not a doctor or nurse.

      It would be of no particular significance for me to focus on one small part of a much larger test. Specifically, when you review a study such as this one:

      You’ll find what is significant, and that is the overall multiple location, multiple nerve groups and multiple motor test results which should include this (where NCS means Nerve Conduction Studies):


      In NCS, the motor nerves, median nerves, and ulnar nerves in the upper limbs were examined by segment; the peroneal nerve and the posterior tibial nerve in the lower limbs were also assessed. The median nerve was stimulated at the wrist, elbow, and axilla. The ulnar nerve was stimulated at the wrist, below the elbow, and at the axilla. The peroneal nerve was stimulated at the ankle and fibular head, and the tibial nerve was stimulated at the ankle and popliteal fossa. For motor nerves, the compound muscle action potential (CMAP) and motor nerve conduction velocity (MNCV) amplitudes obtained by supramaxial stimulations were analyzed by segment. The MNCV was measured in m/sec, and the amplitude was determined in millivolts (mV) by measuring the distance from the negative peak to the positive peak.”

      Finally, the muscle mentioned is used to fully extend the leg. It’s a yes or no test.