EDX-11 · Motor Neuron Disease

Motor Neuron Disease. Topics: ALS, SMA, Kennedy Disease, and Post-Polio Syndrome. Part of the Electrodiagnostics series of the Reflex PM&R Board Review podcast. Audio correction: In the audio: Because the motor neuron pool itself is so severely depleted, you might only have one or two viable anterior horn cells left connecting to that particular muscle. So when you stimulate the nerve 10 times, that exact same solitary motor neuron is the only one capable of backfiring. — Correct: Repeater F-waves indicate a reduced pool of excitable motor units; they do not count the surviving anterior horn cells and are not specific to motor neuron disease. In a study of 50 healthy participants and five disease groups of 50 each, repeaters were more frequent in every disease group, including ALS, diabetic polyneuropathy, entrapments and root lesions, and did not discriminate among those causes (PMID 22431079). This correction is filed from the chapter's attributed quote block and the banked ruling; the live recording was not re-transcribed and no audio cutover was performed. The written chapter is correct. Full correction register: https://www.reflexpmr.com/errata. The full companion chapter and a linked board-style Q-bank set for this topic are at https://www.reflexpmr.com/read/EDX-11.