Fig 1.
The illustration of the coarse graining procedure for scales 1 to τ.
Table 1.
Demographic data of children with absence epilepsy (n = 21).
The EEG was done before anti-epileptic drug was given.
Fig 2.
The multiscale entropy from a single seizure in a single patient.
Multiscale entropy of preictal (blue line) and ictal (red line) states from a single seizure in a single patient, respectively, showing that multiscale entropy with higher sampling frequency (1000Hz, lower panel) can reveal greater difference between ictal and pre-ictal states than lower sampling frequency (200Hz, upper panel). The curve also seems smoother and can be calculated to a larger scale factor. Due to more data points in high sampling frequency, the points on high sampling frequency (lower panel) at scale 20 are corresponding to points on low sampling frequency (upper panel) at scale 4. Each panel represented MSE from one seizure in one patient. The sample entropy was the entropy at scale 1 (marking “*” in the figure).
Fig 3.
The mean of multi-scale entropy of pre-ictal and ictal states in all patients with sampling frequency of 1000 Hz.
Pre-ictal state was represented by the blue line with dots and ictal state was represented by the red line with triangles. The x-axis represented the scale factor and the y-axis represented the multi-scale entropy. The error bars were standard errors. *p<0.01; op<0.05.
Table 2.
Sample entropy in different channels in pre-ictal and ictal states, showing there were no significant differences in most channels of pre-ictal and ictal state.
Table 3.
The complexity index for age-matched controls and inter-ictal, pre-ictal and ictal states of absence seizures showing no difference in age-matched controls, inter-ictal, and pre-ictal state.
However, there was significant decrease of CI values in ictal state compared with pre-ictal state (P < 0.05).
Fig 4.
The mean of complexity index (CI) in pre-ictal and ictal states in all patients with sampling frequency of 1000Hz.
Comparing CI changes in the pre-ictal and ictal states in the occipital areas, the changes were significantly larger in F3, F4, Fz, C3, C4, and Cz. The error bars were standard errors. *p<0.01.
Fig 5.
The variations of complexity index (CI) in different time period for five patients.
Variations of CI at channels Fz and Cz in different time periods for five patients showed consistent CI changes in different seizures during the ictal states for the same patient. In contrast, the CI changes in different patients were not consistent. The different colors represented different seizure episodes in the same patients.
Fig 6.
The variations of complexity index (CI) from epoch a to f in patient 1.
Each epoch represented mean CI value calculated from 5 sec EEG data points from the pre-ictal state to the ictal state. Changes in mean CI were more prominent over the frontal and central areas during ictal state. The top of the figure was the front of the head and the bottom of the figure was the occipital area of the head. Blue color represented low CI value while red color represented high CI value.