S. Koszer et al., SURFACE MAPPING OF SPIKE POTENTIAL FIELDS - EXPERIENCED EEGERS VS COMPUTERIZED ANALYSIS, Electroencephalography and clinical neurophysiology, 98(3), 1996, pp. 199-205
An EEG epileptiform spike focus recorded with scalp electrodes is clin
ically localized by visual estimation of the point of maximal voltage
and the distribution of its surrounding voltages, We compared such est
imated voltage maps, drawn by experienced electroencephalographers (EE
Gers), with a computerized spline interpolation technique employed in
the commercially available software package FOCUS, Twenty-two spikes w
ere recorded from 15 patients during long-term continuous EEG monitori
ng. Maps of voltage distribution from the 28 electrodes surrounding th
e points of maximum change in slope (the spike maximum) were construct
ed by the EEGer. The same points of maximum spike and voltage distribu
tions at the 29 electrodes were mapped by computerized spline interpol
ation and a comparison between the two methods was made. The findings
indicate that the computerized spline mapping techniques employed in F
OCUS construct voltage maps with similar maxima and distributions as t
he maps created by experienced EEGers. The dynamics of spike activity,
including correlations, are better visualized using the computerized
technique than by manual interpretation alone. Its use as a technique
for spike localization is accurate and adds information of potential c
linical value.