The Possibilities of the Activation and Differentiation
of Low-Voltage Electroencephalogram

Synek, V

doi:10.1159/000468844

Cited by 2 publications

(1 citation statement)

References 11 publications

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“…All relevant references have been published previously. [9][10][11] This article is an attempt to summarize my experience over 20 years with a practical approach to the interpretation of LVEEGs. In spite of a significant incidence of LVEEG in routine electroencephalographic practice, the problems of LVEEG are only very briefly mentioned in available EEG textbooks, and over the last decade there have been no articles dealing with this particular subject in English literature.…”

Section: Vm Synekmentioning

confidence: 99%

The Low-Voltage Electroencephalogram

Synek¹

1983

Clinical Electroencephalography

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Section: Vm Synekmentioning

confidence: 99%

The Low-Voltage Electroencephalogram

Synek¹

1983

Clinical Electroencephalography

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Frequency Analysis of the Low-Voltage EEG in Normal Adults

Synek¹

1973

Clinical Electroencephalography

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Low-voltage EEG (LV EEG) can be recorded from approximately 10 per cent of healthy adults (1, 2 ) and is considered a normal variant by most authors (3, 4 ) . Similar EEG patterns may be caused by quite different conditions, decreased vigilance, anxiety, postconcussional syndromes, postencephalitic states, insufficiency of the vertebrobasilar vascular bed, endocrinopathies, physical factors, etc. The present study was designed to provide increased information on the frequency characteristics of LV EEGs in normal adults. It was believed that a finer quantitative method could contribute to distinguishing between different types of low voltage EEGs. With respect to previous experience ( 5 ) , a subgroup of LV EEGs where the decreased voltage was apparently caused by decreased vigilance or drowsiness, was separated and compared with remaining LV EEGs as well as with alpha-dominated recordings. For our purposes a broad-band frequency analysis was employed and the results of an objective measurement statistically evaluated. MATERIAL AND METHODA group of 160 selected healthy adults, 122 males and 38 females was examined. Ages ranged from 19-62 years, with a mean of 37 years. From the study the following were excluded: subjects with an apparent somatic or psychic disorder as well as those with serious illness in the past, trauma or infection of the CNS or neuropsychiatric diseases. Objective neurologic findings, psychological questionnaires and blood pressure were within normal limits in all subjects.The EEGs were recorded in the morning with the subject in the supine position, in an acoustically and electrically shielded room. Reference and bipolar leads were used with electrodes placed according to the "ten-twenty system". The time constant was 0,3 seconds. Band-pass filters of 70 c/s were used. In the course of the EEG examination, repeated eye opening and eye closing tests were carried out, as well as 3 min. of hyperventilation and photic stimulation, with flash frequencies varying between 1-24 c/sec.The EEG recordings were automatically Frequency-analysed using Kaiser-Petersen apparatus ( 6 ) which divided the EEG activity into 6 frequency bands, delta, 1-3.5 c/sec, theta, 3.5-7.5 c/sec, alpha 1, 7.5-9.5 c/sec, alpha 2, 9.5-12.5 c/sec, beta 1, 12.5-17.5 c/sec, and beta 2, 17.5-25 c/sec. For the automatic frequency analysis derivations F3-F7, F4-F8, F3-T5 and P4-T6 were used. For further statistical processing, artifact free epochs of 45 seconds duration from right parietotemporal derivation (P4-T6) were chosen. The quantity of EEG activity was measured separately in each frequency band and the values expressed in microvolt/seconds were entered on punched cards.With respect to the aim of this study three subgroups were selected from the total of 160 subjects: 1. Records with a dominant alpha rhythm, 68 cases with a mean age of 39 years in which alpha activity was present during 50-80 per cent of the recording time and the amplitude exceeded 40 microvolts in the occipital area in bipolar derivations. 2. Low-voltage EE...

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The Possibilities of the Activation and Differentiation of Low-Voltage Electroencephalogram

Cited by 2 publications

References 11 publications

The Low-Voltage Electroencephalogram

The Low-Voltage Electroencephalogram

Frequency Analysis of the Low-Voltage EEG in Normal Adults

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