AANEM Connect

I am occasionally asked to evaluate a patient for myasthenia gravis. I typically evaluate some combination of the ulnar, spinal accessory, deltoid, or facial nerves using a train of four 3 Hz stimuli. I have been surprised by the variability of the results I obtain during individual examinations, not only in the magnitude of decrement but also by the pattern of the decremental response. Sometimes only one or two of the responses show a decrement, whereas other times all responses are smaller than the initial response. Is this variability expected and if not, how do I know the abnormality I find is “real?”