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EDITED BY PROFESSOR YASSER METWALLY |
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Definition of quantitative (digital) EEG |
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Digital EEG techniques have grown rapidly in popularity for
recording, reviewing, and storing EEG. Digital EEG recordings are
flexible in the way they display the EEG tracings, unlike analog
paper EEG. Montage, filter, and gain settings can be changed
retrospectively during record review. Quantitative EEG (QEEG)
analysis techniques can provide additional measurements or displays
of EEG in ways not available with analog paper EEG recordings.
Several QEEG techniques, commonly called "EEG brain
mapping," include topographic displays of voltage or frequency,
statistical comparisons to normative values, and discriminant
analysis. Although much scientific literature has been produced after
decades of research in this field, there remains controversy about
the clinical role of QEEG analysis techniques. This assessment is
meant to help the clinician by providing an expert review of the
current clinical usefulness of these techniques. Click
here for the whole story |
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Problems associated with EEG quantification |
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The potential advantages of QEEG's and its clinical usefulness is now
undoubted, and it has substantial potential for future applications.
At this time, most scientific reports more convincingly have
demonstrated research applications rather than clinical applications.
Among the reports suggesting clinical utility, few have been
prospectively verified or reproduced, and some conflict with others.
Techniques used in QEEG vary substantially between laboratories, and
any clinical usefulness found with one specific technique may not
apply when using a different technique. Many technical and clinical
problems interfere with simple clinical application. Traditional EEG
artifacts can appear in unusual and surprising ways, and new
artifacts can be caused by the data-processing algorithms. Some
artifacts, such as eye movements, are common in the EEG, and even
subtle ones will produce highly significant QEEG abnormalities if
they go unrecognized. Abnormal activity such as epileptiform spikes
may be overlooked, considered artifactual, or misinterpreted.
Transient slowing can be missed. The computer may score as
"abnormal" some EEG activity known to have no clinical
importance, such as mu, or slow alpha variant. Click
here for the whole story |
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Historical difficulties in EEG quantification |
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The desirability of standardized recording procedures and
interpretation has inspired efforts towards quantified analysis
almost since the inception of electroencephalography. There has
traditionally been the hope that with a more powerful computer, or a
more complicated form of analysis, Hans Berger's original dream that
the EEG would be a "window on the mind" might be fulfilled.Click
here for the whole story |
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Textbook of brainmapping: An online list of
all previously published issues |
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