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exhibiting irregularly transient waveforms in a single channel were within IC11 in
Fig. 4.2d, e, IC15 in Figs. 4.3 and 4.4d, e.
Most of the previous studies have reported that only one CJD pattern appeared
in each stage. The co-occurrence of FIRDA and PLEDs or triphasic waves from the
same EEG data has not been explored. For example, either the FIRDA or FIRDA-
like waveforms could be found in the early stage of CJD in most cases [8, 25], or the
PLEDs appeared initially and were replaced by PSWCs progressively in the middle
or late stage [1, 6]. The ICA results, nevertheless, illustrated that the FIRDA and
PLEDs, or FIRDA and epileptiforms, or FIRDA and triphasic waves concurrently
appeared in the same EEG data for each patient. As shown in Table 4.2, the PLEDs,
epileptiforms, and triphasic waves from the 5-min EEG signals of patient 1 can
be, respectively, recovered in IC3, IC5, and IC4, the FIRDA, PLEDs, and triphasic
waves in IC6 (shaded area in Fig. 4.5a), IC3 (stars in Fig. 4.5a), and IC1 (arrows
in Fig. 4.5a) from patient 2, and in IC8 (shaded area in Fig. 4.5d), IC7 (stars in
Fig. 4.5d), and IC2 (arrows in Fig. 4.5d) from patient 5. In addition, FIRDA can be
seen in IC8 (shaded area in Fig. 4.5b) and epileptiforms in IC6 and IC7 (arrows in
Fig. 4.5b) from patient 3, and FIRDA in IC2 and IC4 (shaded area in Fig. 4.5c) and
epileptiforms (arrows in Fig. 4.5c) in IC6 from patient 4. These findings suggest that
the EEG in the early stage of CJD is heterogeneous and concurrent appearance of
different CJD patterns should be taken into account in the diagnosis.
Table 4.2: The concurrent appearance of different CJD waveforms in the same EEG
data from each patient
Patient
FIRDA
PLEDs
Epileptiform
Triphasic wave
1 (Figs. 4.2, 4.3, and 4.4)
IC3 IC5
IC4
2 (Fig. 4.5)
IC6
IC3
IC1
3 (Fig. 4.5)
IC8
IC6, IC7
4(Fig. 4.5)
IC2, IC4
IC6
5 (Fig. 4.5)
IC8
IC7
IC2
It should be noted that only the PSWC had been reported with a 85% specific
to the late CJD, the unaccompanied occurrence of each pattern, such as FRIDA,
epileptiform, PLED, and triphasic waves, might be seen in other neurological disor-
ders. Therefore, the hypothesis that EEGs of the CJD manifested the co-occurrence
of multiple disease-related features was further tested against the Alzheimer's dis-
ease (AD) group with five patients who were all male and aged 85, 73, 45, 72, and
79 years old, i.e., age and gender matched with the CJD group. After applying ICA
on the AD group, we examined the independent components to detect the disease-
related features. No co-occurrence of multiple disease-related features was found in
the AD group, except that two ICs were detected to consist of FIRDA in patient 1
and one IC consisted of the epileptiform in patient 4. Based on the co-occurrence
of multiple disease-related features exhibited in both groups, the difference be-
tween AD and CJD groups was statistically significant (two-sample Wilcoxon test,
