Checkpoint: Everything You Wanted to Know About Nerves, but Were Afraid to Ask-Drs. Little and Mosser Presentation

Drs. Little and Mosser Presentation

Pdf Summary

The presentation by Dr. Clark Moser and Dr. Ann Little covers in-depth topics on nerve physiology and conduction studies. It begins with an overview of nerve structure, describing nerves as cables of axons of varying sizes with larger axons having thicker myelin, which allows faster conduction. Basic principles such as Ohm's Law are applied to understand the varying resistance in different axon sizes.<br /><br />Key points include the importance of warming up patients to ensure proper ion channel function, which is slowed by cold temperatures. The presentation explains why motor conduction studies often involve stimulation at two points to accurately measure conduction velocity, whereas sensory studies might not due to phase cancellation risks.<br /><br />The distinction between CMAP (Compound Motor Action Potential) and MUAP (Motor Unit Action Potential) is clarified. CMAPs are reliant on the neuromuscular junction and muscle integrity, as opposed to SNAPs (Sensory Nerve Action Potentials), which directly measure sensory axon integrity. Conduction velocity and demyelination are also discussed, emphasizing that mild slowing is not always indicative of demyelination and criteria for demyelination diagnoses include conduction velocity and distal latency thresholds.<br /><br />Methods to localize lesions using sensory nerve studies are outlined, with normal sensory studies suggesting proximal lesions and abnormal studies indicating distal lesions. The presentation addresses repetitive stimulation for diagnosing neuromuscular junction disorders and details late responses like H-reflex and F-waves used in different diagnostic scenarios.<br /><br />Practical advice for troubleshooting issues such as waveform accuracy and electrode placement is provided, alongside considerations of patient factors like temperature, height, and age affecting results. The presentation concludes with a case study analyzing conduction velocities and references for further reading.<br /><br />Attendees are encouraged to provide feedback via the AANEM app and record their session attendance for credit reporting by December 15, 2023.

Keywords

nerve physiology

conduction studies

nerve structure

Ohm's Law

CMAP

SNAP

demyelination

lesion localization

neuromuscular junction

nmj

diagnostic methods

nmj

neuromuscular junction