Have you ever encountered a patient with progressive patchy weakness in various muscles throughout the body? Have you ever performed an EMG in which the findings don’t always fit perfectly into what you were expecting?  Have you ever wondered whether you even need to perform an EMG in a patient with weakness? Have you ever wondered how much fun it would be to listen to a new episode of Lessons From the Lab? Well, you have come to the right place to find some answers to these questions! Join Drs. Rubin and Narayanaswami as they ponder and discuss many clinical, electrodiagnostic, and practical approaches to an interesting patient with progressive weakness.

 6/22/2017-   Dr. Justin Willer interviews Dr. Yuebing Li about optimizing muscle selection for electromyography in amyotrophic lateral sclerosis. He was part of a group that compared the yield of limb and thoracic paraspinal muscle examination for revealing lower motor neuron (LMN) dysfunction on electromyography (EMG) in amyotrophic lateral sclerosis (ALS). Distal limb muscles showed the highest electrodiagnostic sensitivities of LMN dysfunction in ALS regardless of onset region and diagnostic certainty at the time of diagnosis. Electrodiagnostic yield is higher in muscles from the onset limb. Noncontiguous spread of lower motor neuron degeneration is present in ALS. Optimally selected 6 upper and 5 lower extremity muscles yielded >98% of potential positive cervical or lumbosacral segments. An algorithmic approach to needle EMG in ALS based on pretest probability of individual muscles optimizes electrodiagnostic yield, thus possibly minimizing test duration and patient discomfort. Muscle Nerve. 2016 Oct 19. doi: 10.1002/mus.25444.