Effect of triggering potential on calculations of jitter in single-fiber EMG.
Jitter values are calculated in reference to a triggering potential during single-fiber electromyography (SFEMG) performed during voluntary contraction. When there are more than two single-fiber action potentials (SFAP) and the selected triggering potential is from an abnormal end-plate, all the jitters calculated from the same trace will be affected. In this study, the effect of triggering potential on calculated jitter was investigated in myasthenic and healthy volunteers by switching the triggering potential and recalculating the jitter off-line. Selecting a triggering potential from an abnormal end-plate increased the number of abnormal individual jitters as well as the mean jitter. Therefore, if the equipment software has the capacity to change the trigger potential, the triggering potential should not be from an abnormal end-plate if all possible jitter values are to be calculated for traces having three or more single-fiber potentials. Otherwise, only one jitter value should be included from any one trace to prevent false-positive results.
Department of Neurology, Istanbul Medical Faculty, Istanbul University, Capa, Istanbul 34390, Turkey. barisbaslo@hotmail.com
M Bariş
MB
Baslo
Nebil
N
Yildiz
Pinar
P
Yalinay
Mustafa
M
Ertaş
D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D016477:Artifacts; D004576:Electromyography / Q000379:methods*; D006801:Humans; D009119:Muscle Contraction / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D009157:Myasthenia Gravis / Q000503:physiopathology; D012016:Reference Values; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted