AAEM MINIMONOGRAPH NUMBER-16 - INSTRUMENTATION AND MEASUREMENT IN ELECTRODIAGNOSTIC MEDICINE .2.

A review of instrumentation and measurement in electrodiagnostic medic ine is continued in this Part II which focuses on digital instrumentat ion principles, gain and sweep effects, noise, nerve stimulation, and conduction measurement limitations. With the adoption of microprocesso r-based equipment, the neurophysiologic signal must undergo analog-to- digital conversion (ADC) before analysis and display on a video monito r. ADC resolution and sampling rates affect accuracy and measurement p recision, Following waveform display, the visual assessment of latency and duration may be influenced by sweep and gain settings, often over looked sources of error. Undesired signal or noise typically originate s from power-line interference, electronic amplifier noise, background muscle activity, or nerve stimulation artifact. Noise often interfere s with clinical studies but techniques exist to reduce noise to accept able levels in virtually all situations. An awareness and understandin g of these technical issues will lead to an appreciation of the limita tions of electrodiagnostic testing and improve interpretation and clin ical decision-making. (C) 1995 Andrew J. Gitter, MD, and Waiter C. Sto lov, MD. Published by John Wiley and Sons, Inc.