2017 Volume 66 Issue 3 Pages 225-233
The jerk-locked back averaging (JLA) analytical method is performed by addition-averaging an electroencephalogram (EEG) following the onset of the myoclonus when it appears during measurement using an evoked potential inspection device. We developed original software that can perform JLA analysis from recorded video digital EEGs. In the present study, we aimed to evaluate the efficacy of this software for JLA analysis. Video digital EEGs from an 8-month-old girl with Dravet syndrome (case 1) and an 11-year and 5-month old girl with involuntary movement (case 2) were used. The following protocol was used for the JLA analysis: (1) the video digital EEGs were reproduced, (2) the onset of the rise of the electromyogram associated with myoclonus-like involuntary movement was noted, and (3) the addition-averaging method was applied to the EEG between 140 ms before and after the onset. Since an electronegative wave that was approximately 20–30 μV was present 60 ms before the onset, case 1 was suggested to be cortical myoclonus. In case 2, however, no meaningful electroencephalographic changes were recognized. The JLA analysis of video digital EEGs was useful in the diagnosis of cortical myoclonus. Furthermore, the JLA software that we developed was particularly useful for the diagnosis in infants in whom the measurements are difficult to perform.
