What is the stimulus rate of electrical stimulation of somatosensory evoked potentials (SEPs)?

Updated: Feb 26, 2019
  • Author: Sombat Muengtaweepongsa, MD, MSc; Chief Editor: Selim R Benbadis, MD  more...
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Answer

Answer

Rapid stimulus delivery rates should be avoided, as they degrade the SEP waveforms. In clinical settings, a rate of 3-6 stimuli per second is usually used. Rates that are exact subharmonics of the line frequency (eg, 5.0 Hz) should be avoided, since their use would lead to contamination of the averaged SEPs by large artifacts of the line frequency (50 or 60 Hz). Signal averaging reduces noise that is random with respect to stimulus delivery while retaining signals that are time-locked to stimulus delivery. If the stimulus rate is an exact subharmonic of the line frequency, the inevitable line-frequency noise will be at the same phase in each data epoch, and will be preserved rather than eliminated during the averaging process.


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