EDX-03 · Nerve Conduction Studies

Nerve Conduction Studies. Part of the Electrodiagnostics series of the Reflex PM&R Board Review podcast. Audio corrections: (1) In the audio: Type 1 is the most common, where the crossover fibers go to the hypothenar muscles. — Correct: The first dorsal interosseous is a common MGA destination and was involved in all 26 detected cases in Hasegawa’s 106-patient series. The 11% hypothenar figure used all 106 tested patients, not the 26 MGA cases. Routine ADM recording can miss FDI crossover. Name the recording muscle rather than assuming a universal numbered type scheme. (2) In the audio: When a limb gets cold, SNAP amplitude actually rises. Meanwhile, the CMAP amplitude barely changes. — Correct: Cooling can raise the amplitude of both the SNAP and the CMAP. In ten healthy upper limbs warmed and cooled through physiological temperatures, sensory and thenar motor response amplitude, duration and area all changed (PMID 7264687). The teaching contrast that survives is the direction of the latency and velocity change, not a claim that the CMAP amplitude is unaffected. The rest of the passage is right: latencies prolong and conduction velocity slows with cooling, and the fix is to warm the limb to the laboratory protocol and repeat rather than to apply a correction factor. 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-03.