An Introduction to the Basic Concepts of Polarity and Localization*, †

Lesser, R.P.; Lüders, Hans; Dinner, Dudley S.; Morris, H. A.

doi:10.1097/00004691-198501000-00003

Cited by 26 publications

(6 citation statements)

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“…Many of the reports for the EEGs in this study contained a description clearly implying that the ‘phase reversal’ indicated an epileptiform discharge. Basic principles of polarity and localization [38, 45, 46] make it clear that phase reversals are not at all indicative of abnormalities; they only indicate location (maximum voltage). ‘Phase reversals’ are not even one of the criteria used to determine if a discharge is of epileptogenic significance.…”

Section: Discussionmentioning

confidence: 99%

Errors in EEG Interpretation and Misdiagnosis of Epilepsy

2008

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Background/Aims: The overinterpretation of EEGs is common and is an important contributor to the misdiagnosis of epilepsy. We reviewed our experience in order to clarify which EEG patterns are commonly overread as epileptiform. Methods: We identified patients who were seen at our epilepsy clinic and were ultimately diagnosed as having conditions other than epilepsy. We selected those who had previously had an EEG read as showing epileptiform discharges and whose EEG was available for our own re-review. Results: 37 patients met the above criteria. Eventual diagnoses were psychogenic nonepileptic seizures (10), syncope (7), other miscellaneous diagnoses (5) and unexplained nonspecific symptoms (15). None of the EEGs had epileptiform discharges. The descriptions of the abnormalities included ‘temporal sharp waves’ in 30, ‘frontal sharp waves’ in 2 and ‘generalized spike-wave complexes’ in 2. Three had no reports available to identify the alleged abnormality. The benign patterns mistaken for temporal (30) and frontal (2) sharp waves were simple fluctuations of background activity with temporal phase reversals. Conclusions: By far the most common patterns overread as epileptiform are nonspecific fluctuations of background in the temporal regions, which are misread as temporal sharp waves.

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Section: Discussionmentioning

confidence: 99%

Errors in EEG Interpretation and Misdiagnosis of Epilepsy

2008

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“…The contrasting role is undoubtedly played by the amount of electroencephalographic literature regarding that kind of examination in humans. Most of the technical aspects, such as electrodes localization, research apparatus used and ranges of particular brain waves are widely known and successfully used in practice (Lesser et al 1985, Butler 1987, Homan et al 1987, Rosenblatt et al 1999, Vock et al 2002, Danko et al 2002, Armitage et al 2003, Velis 2005. Despite the many different opinions of researchers, it is certain that the electroencephalographic diagnostic is regarded highly among neurophysiological examinations and may be successfully used, not only in humans but in animals as well.…”

Section: Electroencephalography Application In the Research On The Cementioning

confidence: 99%

Recording of bioelectrical activity changes in sheep cerebral cortex

Cwynar

Zawadzki

2010

Arch. med. vet.

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RESUMENEl objetivo de este estudio es presentar el uso práctico de la electroencefalografía (EEG), demostrando el aspecto básico de EEG en ovejas, así como su utilidad en el análisis de las alteraciones provenientes del sistema nervioso central. Se examinaron 10 hembras híbridas de Oveja Merino Polaca, seleccionadas especialmente con fines experimentales. Debido a la falta de una fórmula unificada en el método de EEG en animales, se realizó un registro de potenciales provenientes de algunos puntos escogidos tras el experimento en cabezas de animales. Durante los experimentos realizados se demostró que la corteza cerebral de ovejas se caracteriza por una dinámica muy alta, hecho que fue demostrado al examinar las reacciones del sistema nervioso central a los factores tales como: el hambre, la estimulación auditiva o la inyección de xylazyna. La corteza cerebral de ovejas en el estado de reposo muestra una actividad bioeléctrica de una amplitud media de 30 μV y una frecuencia de 25 Hz, con lo cual se confirma la existencia del ritmo beta [β]. La aplicación de un estímulo acústico permite estimular el sistema nervioso central de oveja, lo que queda comprobado por una elevación de la amplitud media (por 23%) y de la frecuencia (por 21%) de la actividad bioeléctrica de la corteza cerebral, como también lo confirma el electroencefalograma conseguido. Los datos obtenidos demuestran que la zona que se caracteriza por tener el tiempo más corto de reacción es la zona del mesencéfalo, con un tiempo medio de reacción de 0,56 segundos (± 0,005 s). Se discute además la aplicabilidad de los experimentos, así como también la posibilidad de unificar el método de EEG.

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“…To date, no single EEG feature has been identified to represent background or spikes because of numerous false positives on long-term EEG recordings [17]. The novel approach in this study is based on neurophysiologic knowledge applied by neurologists or epileptologists during their evaluation of clinical EEG in daily practice [30], [31]. The primary concept is to use the principles of field potential and phase reversal.…”

Section: Discussionmentioning

confidence: 99%

“…The primary concept is to use the principles of field potential and phase reversal. Many neuronal elements contribute to the extracellular currents that generate field potentials recorded on the surface of the brain [30], [31], [32]. Furthermore, field potentials recorded during epileptic activity are based on changes in neuronal membrane potential.…”

Section: Discussionmentioning

confidence: 99%

“…To elaborate on the contribution of this report, there are four major points of novelty. First, we applied neurophysiologic knowledge applied by neurologists during their evaluation of clinical EEG in daily practice [30], [31]. The primary concept is to use the principle of field potential and phase reversal by evaluating potential differences of the neighboring electrodes.…”

Section: Discussionmentioning

confidence: 99%

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A Physiology-Based Seizure Detection System for Multichannel EEG

et al. 2013

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BackgroundEpilepsy is a common chronic neurological disorder characterized by recurrent unprovoked seizures. Electroencephalogram (EEG) signals play a critical role in the diagnosis of epilepsy. Multichannel EEGs contain more information than do single-channel EEGs. Automatic detection algorithms for spikes or seizures have traditionally been implemented on single-channel EEG, and algorithms for multichannel EEG are unavailable.MethodologyThis study proposes a physiology-based detection system for epileptic seizures that uses multichannel EEG signals. The proposed technique was tested on two EEG data sets acquired from 18 patients. Both unipolar and bipolar EEG signals were analyzed. We employed sample entropy (SampEn), statistical values, and concepts used in clinical neurophysiology (e.g., phase reversals and potential fields of a bipolar EEG) to extract the features. We further tested the performance of a genetic algorithm cascaded with a support vector machine and post-classification spike matching.Principal FindingsWe obtained 86.69% spike detection and 99.77% seizure detection for Data Set I. The detection system was further validated using the model trained by Data Set I on Data Set II. The system again showed high performance, with 91.18% detection of spikes and 99.22% seizure detection.ConclusionWe report a de novo EEG classification system for seizure and spike detection on multichannel EEG that includes physiology-based knowledge to enhance the performance of this type of system.

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An Introduction to the Basic Concepts of Polarity and Localization*, †

Cited by 26 publications

References 0 publications

Errors in EEG Interpretation and Misdiagnosis of Epilepsy

Errors in EEG Interpretation and Misdiagnosis of Epilepsy

Recording of bioelectrical activity changes in sheep cerebral cortex

A Physiology-Based Seizure Detection System for Multichannel EEG

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