New-Onset Alzheimer's Disease and Normal Subjects 100% Separated Statistically by P300 and ICA.

Previously, we described how patients with new-onset Alzheimer's disease were differentiated from healthy, normal subjects to 100% accuracy, based on the amplitudes of the nonrhythmic back-projected independent components of the P300 peak at the electroencephalogram electrodes and their latency in the response to an oddball, auditory evoked potential paradigm. A neural network and a voting strategy were used for classification. Here, we consider instead the statistical distribution functions of their latencies and amplitudes and suggest that the 2-sample Kolmogorov-Smirnov test based upon their latency distribution functions offers an alternative biomarker for AD, with their amplitude distribution at the frontal electrode fp2 as possibly another. The technique is general, relatively simple, and noninvasive and might be applied for presymptomatic detection, although further validation with more subjects, preferably in multicenter studies, is recommended. It may also be applicable to study the other P300 peaks and their associated interpretations.

Paraplegia due to non-osseous spinal tuberculosis: report of three cases and review of the literature.

BACKGROUND: In developing countries, a recognized etiology of paraplegia can be tuberculous radiculomyelitis or tuberculomas, especially in patients with evidence of either active or latent tuberculosis. These entities should also be considered in high-risk patients or in patients who have emigrated from regions with a high prevalence of tuberculosis (TB). Both arachnoiditis and intradural tuberculomas are uncommon forms of spinal TB. CASE REPORTS: We report three cases of TB of the spinal cord in young males with paraplegia or paraparesis who were hospitalized over a one-year period. The clinical presentation and clinical course differed among the three patients: radiculomyelitis complicating tuberculous meningitis for the first patient and spinal tuberculomas in the other two. Neuroimaging with magnetic resonance imaging (MRI) was critical for diagnosis. CONCLUSIONS: The therapy for spinal TB should be conservative since the neurologic deficits are mainly secondary to the inflammatory process. Usually these lesions respond to medical therapy alone, and with early diagnosis one can avoid unnecessary surgical intervention. In our limited clinical experience, corticosteroids (IV, intrathecal, or both) appear to have a beneficial effect.

The independent components of auditory P300 and CNV evoked potentials derived from single-trial recordings.

The back-projected independent components (BICs) of single-trial, auditory P300 and contingent negative variation (CNV) evoked potentials (EPs) were derived using independent component analysis (ICA) and cluster analysis. The method was tested in simulation including a study of the electric dipole equivalents of the signal sources. P300 data were obtained from healthy and Alzheimer's disease (AD) subjects. The BICs were of approximately 100 ms duration and approximated positive- and negative-going half-sinusoids. Some positively and negatively peaking BICs constituting the P300 coincided with known peaks in the averaged P300. However, there were trial-to-trial differences in their occurrences, particularly where a positive or a negative BIC could occur with the same latency in different trials, a fact which would be obscured by averaging them. These variations resulted in marked differences in the shapes of the reconstructed, artefact-free, single-trial P300s. The latencies of the BIC associated with the P3b peak differed between healthy and AD subjects (p < 0.01). More reliable evidence than that obtainable from single-trial or averaged P300s is likely to be found by studying the properties of the BICs over a number of trials. For the CNV, BICs corresponding to both the orienting and the expectancy components were found.