NCS Perils and Pitfalls-Dr. Robinson - NCS Perils and Pitfalls

Dr. Robinson - NCS Perils and Pitfalls

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In this document, Dr. Larry Robinson discusses various topics related to instrumentation and reference values in nerve conduction studies. He starts by mentioning an issue he faced at his hospital where they questioned the need for five electrodes in nerve conduction studies and suggested using only two. He explains that using two electrodes for recording may include unwanted noise, so a third electrode is necessary to record only the noise. He also explains the importance of using multiple electrodes for stimulation to create a voltage and current between two points in space.<br /><br />Dr. Robinson then talks about the different choices he has when his technician mistakenly switched the cathode and anode during sensory conduction studies. He suggests options like ignoring the mistake, electronically fixing the waveforms, re-doing the studies and charging twice, or adjusting the latencies.<br /><br />In terms of measuring onset latencies in CMAPs, Dr. Robinson highlights the disagreement among colleagues regarding the display gain. He explains that the marker placement determines the onset latency, and a bigger gain allows for the appreciation of deflections earlier.<br /><br />Dr. Robinson also addresses the need for normal/reference values in nerve conduction studies. He clarifies that these values are not meant to determine if someone is truly "normal" but rather to help differentiate between results from healthy individuals and those with diseased nerves. Obtaining normal/reference values involves studying healthy control subjects but can be a complex process.<br /><br />When it comes to prognosis, Dr. Robinson discusses the measures that can be useful in assessing axon loss, demyelination, and reinnervation. He explains the significance of measures like CMAP amplitude, SNAP amplitude, nerve conduction velocity, spontaneous activity, and recruitment.<br /><br />Overall, Dr. Robinson provides insights into various aspects of nerve conduction studies, including instrumentation, reference values, and prognosis.

Keywords

instrumentation

reference values

nerve conduction studies

electrodes

recording noise

stimulation

onset latencies

CMAPs

display gain

prognosis

ncs