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were difficult to be detected from the smeared EEG. Clear CJD-related waveforms,
i.e., frontal intermittent rhythmical delta activity (FIRDA), fore PSWCs (triphasic
waves), and periodic lateralized epileptiform discharges (PLEDs), have been suc-
cessfully and simultaneously resolved from all patients. The ICA results elucidate
the concurrent appearance of FIRDA and PLEDs or triphasic waves within the same
EEG epoch, which has not been reported in the previous literature. Results show
that ICA is an objective and effective means to extract the disease-related patterns
for facilitating the early diagnosis of CJD.
4.1 Introduction
Creutzfeldt-Jakob disease (CJD) is a rare prion disorder of brain, with an approxi-
mated incidence of 0.5-1 case per million persons per year. The subtypes of human
prion diseases can be familial, sporadic, or acquired, which are characterized by
combination of clinical findings such as duration of disease, EEG changes, age at
onset, and predominant neurological signs. Sporadic CJD (sCJD) is the most com-
mon subtype of CJD that usually develops in the 5th to 7th decade of life, with a
mean age of onset of 62 years old (median 65). Survival times ranging from 1 to 58
months have been reported [24]. The clinical presentations such as memory loss, vi-
sual disturbances, involuntary movements, myoclonus, dementia, and coma can be
observed subsequently from early to the terminal stage of the disease. Since CJD is
a rapidly progressive, uniformly fatal, and transmissible spongiform encephalopa-
thy, detection of the CJD symptom in the early stage is crucial to avoid the fatal
transmission.
Electroencephalography (EEG), cerebral magnetic resonance imaging (MRI),
and cerebrospinal fluid analysis (CSF analysis) are currently the most common di-
agnostic means of CJD. To evaluate these techniques, Collins et al. investigated
the influence of several clinical parameters, such as prion protein gene codon 129
polymorphism, molecular subtype, age at disease onset, and illness duration, on
the diagnostic sensitivity to EEG, cerebral MRI, and the CSF analysis. They re-
ported that the CSF analysis had the highest sensitivity for early diagnosis since
the 14-3-3 protein could be detected from the CSF after the disease had onset [14].
However, Geschwind et al. concluded that the sensitivity of CSF analysis in their
study was only 53% and advised that it was risky to exclude the diagnosis of
CJD in the case of negative CSF results [7]. Besides, the use of CSF 14-3-3 anal-
ysis, regardless of methods, is problematic since universally accepted standards
are not available for performing such tests. Magnetic resonance brain imaging is
another developing tool for detecting CJD. The study conducted by the Schr oter
et al. revealed T2-weighted MRI alternations in 109 (67%) out of 162 sporadic
CJD patients [20], whereas the sensitivity of abnormal T2-weighted or diffusion-
weighted MRI reported by Collins et al. was 43% [3]. Accordingly, efforts to de-
velop more effective techniques for the aid to early diagnosis are of potentially great
importance.
