Berger's persistent, hardworking and steady personal style overcame all technical and other obstacles during the experiments. Unfortunately, he gained neither acceptance nor recognition, among his fellow contemporaries from abroad. Political turmoils at the dawn of World War II, in the country of Nazi's ideology and finally the outbreak of war, along with the complete ban of any further work on EEG after his forced retirement, led him to an uneasy professional and personal end.
In the era when lumbar puncture, pneumoencephalography and ventriculography were the only diagnostic tools to detect and localize "sick sites" in the brain, EEG revolutionized daily neurologic and neurosurgic procedures, and bridged a time period of about 40 years until the advent of computer tomography.
Nowadays its importance is not as great as it was before, but it still has its place in the diagnostic work-up of seizures, brain tumors, degenerative brain changes, and other diseases. Abstract The discovery of electroencephalography EEG in by the German psychiatrist Hans Berger was a historical breakthrough providing a new neurologic and psychiatric diagnostic tool at the time, especially considering the lack of all those now available in daily practice EP, CT, MRI, DSA, etc.
Publication types Biography Historical Article Portrait. Please see Appendix 1 for further details on neurophysiologic principles underlying the EEG.
An unfortunate reality of EEG is that cerebral activity may be overwhelmed by other electrical activity generated by the body or in the environment.
To be seen on the scalp surface, the miniscule, cerebrally generated EEG voltages must first pass through multiple biological filters that both reduce signal amplitude and spread the EEG activity out more widely than its original source vector.
Cerebral voltages must traverse the brain, CSF, meninges, the skull, and skin prior to reaching the recording site where they can be detected.
Additionally, other biologically generated electrical activity by scalp muscles, the eyes, the tongue, and even the distant heart creates massive voltage potentials that frequently overwhelm and obscure the cerebral activity.
The bottom line is that biological and environmental electrical artifacts frequently interfere with the interpreter's ability to accurately identify both normal rhythms and pathological patterns. Fortunately, artifacts possess many distinguishing characteristics that are readily identifiable by well-trained, careful observers. Please see Appendix 4 for several examples of artifacts commonly encountered during EEG recording.
A typical EEG display graphs voltages on the vertical domain and time on the horizontal domain, providing a near real-time display of ongoing cerebral activity Figure 1. With digital recording and review, the interpreter can change several aspects of the EEG display for convenience and intelligibility of the data. Conversely, the time scale may be expanded to display longer segments of EEG over several minutes to look at slowly evolving rhythmic discharges.
Digital filters may also be applied to reduce artifact in certain settings but must be used with great caution since they also filter EEG activity of interest and may distort EEG waveforms severely. Normal EEG with typical montage. An example of the EEG recorded during wakefulness in a year-old woman.
This is a second duration epoch. The first four channels, together referred to as a chain, show cerebral activity recorded from the midline head more EEG uses the principle of differential amplification, or recording voltage differences between different points using a pair of electrodes that compares one active exploring electrode site with another neighboring or distant reference electrode.
Only through measuring differences in electrical potential are discernible EEG waveforms generated. Other polarity possibilities are shown in Figure 2. Polarity conventions and localization in EEG. An upward deflection is surface negative, and a downward deflection is surface positive. Swartz and Eli S. Swartz , E. Save to Library Save.
Create Alert Alert. Share This Paper. Methods Citations. Results Citations. Topics from this paper. TimeLine Fluoride Releasing Resin. Citation Type. Has PDF.
0コメント