What are somatosensory evoked potential (SEP) tests?

Updated: Oct 25, 2019
  • Author: Andrew B Evans, MD; Chief Editor: Selim R Benbadis, MD  more...
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Answer

Answer

The first evoked potential (EP) measurement is credited to Richard Caton of Liverpool, England, in 1913, but he could not record his results because he had no camera. About 34 years later, the first human scalp recording was accomplished. Major improvements included introduction of the first signal averager (by Dawson in 1954) and of the first modern averager, in 1958.

The actual somatosensory EP (SEP) is considered to be the result of summated effects of action potentials and synaptic potentials in a volume conductor. The short-latency SEP (SLSEP) is considered to be generated from volleys traversing the large-fiber sensory system (ie, the posterior columns and medial lemnisci). Studies have shown that simply changing the size and shape of the volume conductor can create voltage differences at the surface.


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