Central nervous system amplification: its potential in the diagnosis of early multiple sclerosis.
Ability to record a sizable somatosensory evoked potential (SEP) in the absence of a recordable sensory nerve action potential (SNAP) suggests a normally occurring central nervous system amplifying process. Increments in SEP and SNAP amplitude with increasing stimulus strength between threshold and 2.5 times threshold (maximum) were compared. A threshold (40% of maximum stimulus) and 50% maximum stimulus, amplification measured 2.3 +/- 0.7 and 2.0 +/- 0.6, respectively. In 21 MS patients, the SEP at threshold stimulation was absent in 15, but normal in 5 of these at maximum stimulation. It is postulated that normal central amplification is markedly attenuated in MS, and this may be a sensitive indicator of early disease.
D000328:Adult; D002490:Central Nervous System / Q000503:physiopathology*; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000175:diagnosis* / Q000503:physiopathology