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PubMed2001

[Comparison of (1)H MRS, PET and EEG in lateralization of temporal lobe epilepsy].

OBJECTIVE: To evaluate and compare the role of (1)H MRS, PET and EEG in lateralization diagnosis (LD) of temporal lobe epilepsy (TLE). METHODS: 15 patients with intractable TLE verified by operation and pathology were studied. Before unilateral anterior temporal lobectomy, (1)H MRS, PET and EEG were performed for the LD of TLE. The diagnostic value of (1)H MRS, PET and EEG was compared based on the pathology and follow-up results. RESULTS: With video scalp EEG monitoring, the focus was localized in one temporal lobe for 13 patients among which 5 had abnormal waves conducted to the contralateral lobe. Intracranial EEG was performed for other 2 patients because scalp EEG failed to make the LD. Ultimately, partial temporal lobectomy was performed in all patients based on LD by scalp EEG or intracranial EEG. The pathological findings of operation specimens showed various degree of hippocampal sclerosis. The surgery was proved to be effective by follow-ups of all 15 patients, with their conditions controlled in 12 cases and better in two. EEG succeeded to make correct LD in all cases. (1)H MRS made correct LD in 12 cases (80%) and incorrect LD in 1 case, and failed to made LD in 2 cases. Five bilateral abnormalities (33%) were found by MRS. FDG-PET made correct LD in 14 cases (93%) and incorrect LD in 1 case, and found two cases with bilateral abnormalities (13%). CONCLUSION: (1)H MRS, PET and EEG are all effective means in LD of TLE. Up to now, scalp EEG is the first choice and continuous video EEG monitoring has its own unique advantage. As a kind of simple, noninvasive and objective method, MRS can be used as a routine examination in conjunction with conventional MRI. Although PET is quite sensitive, it is expensive and has a number of limitations. So it can be used depending on the affordability of patients or diagnostic need. Combination of MRI, MRS, PET and scalp EEG may improve the reliability of the LD compared with use of any one of them alone. While the results of these methods are controversial, intracranial EEG is inevitable.

Adolescent↗
PubMed1988

Quantitative EEG: II. Frequency analysis and topographic mapping in clinical settings.

The results of many studies using quantitative EEG techniques in clinical settings have been published. Those reports are reviewed here, with emphasis on those that used EEG frequency analysis and topographic mapping. In cerebrovascular disease, these methods can confirm the existence of lesions that are too mild to show up on routine EEG or too mild or too early to show up on computed tomography. The results correlate well with cerebral blood flow studies. These EEG tests can be done continuously in an intensive care unit or operating room. However, exact localization ability is inferior to that seen using traditional neuroimaging tests. In epilepsy, quantitative EEG techniques have found subtle degrees of background EEG changes near epileptic foci. Other methods can quantify epileptic spikes in useful ways and can indicate which region is driving other regions during seizures. Quantification is also useful for measuring drug effects when drugs (such as thiopental) are given deliberately to provoke acute EEG changes. Other measurements of drug effects may become useful in the future. In patients with mass lesions and metabolic encephalopathies, quantitative EEG changes do occur, and some of these correlate with the clinical state. However, in the latter settings, the clinical advantages for patient care are not yet clear, especially in comparison to available neuro-imaging studies and other routine medical tests. For dementia, quantitative EEG techniques are being developed. Some of these tests are accurate in moderately or severely demented patients, but there is still poor accuracy for early or borderline cases. For dyslexia, schizophrenia, and depression, there is a considerable volume of research reports but still no consensus about how to use quantitative EEG tests for care of individual patients. These tests require substantial user expertise in EEG. At present, these tests should be viewed as adjunctive to traditional EEG testing: such routine EEG testing should serve as the foundation for any clinical use of quantitative EEG tools.

Brain↗
PubMed1976

The development of the EEG in the rat.

The development of the electroencephalogram (EEG) and, especially, behavioral state-specific EEG patterns was studied in white and black hooded rats of the Lister strain, aged 9-30 days. Movements of the rat were recorded and the behavioral state was monitored by means of a push-button device. The EEG was collected when the rat was in State 1 (regular respiration, absence of movements, and, after the 14th day when the rat eye opens, eyes closed), State 2 (irregular respiration, continual occurrence of twitches, and, after the 14th day, eyes closed), and in State 4 (irregular respiration, presence of gross body movements, and, after the 14th day, eyes opened). The EEG of rats on the 9th and 10th day did not reveal behavioral state-specific patterns. The amplitudes of the EEG were low and only low frequencies occurred. Between the 10th and 13th day an EEG pattern specific for State 1 containing high amplitudes developed. From the 14th day onwards spindles (frequencies from 14-18 Hz) occurred in the EEG during State 1. From the 14th day onwards, the EEG from the visual cortex during State 2 showed a regular and continually occurring 5-Hz rhythm. Bursts with 5-Hz waves were recorded from the visual cortex only intermittently during State 4. The EEG frequencies during the bursts varied between 5 and 7 Hz from the 17th day onwards. Computer analysis of the amplitude distributions showed a considerable increase in the power after the 10th day. The analysis of the frequency spectra indicated that the power increase occurs expecially in the higher frequencies of the EEG signal. Visual analysis as well as computer analysis of the EEG did not reveal systematic changes in the EEG after the 18th day when the EEG was similar to that recorded at older ages.

Age Factors↗
PubMed1980

Correlations between EEG and chemical changes in uremia.

This study investigated correlations between the EEG and 10 different chemical indices in 23 uremic patients, tested over long periods of time (up to 18 months). An abnormal EEG was recorded at least once in 70% of these patients, but among the 362 tracings from all patients, 36% were considered abnormal. Slow wave abnormalities, mainly mild in degree and frontal in location, were found in 97% of abnormal records and epileptiform patterns in the form of bilateral spike and wave complexes were seen in 14%. Patients with these EEG abnormalities had a significantly slower frequency of background rhythm than patients with normal EEGs. Compared to those with normal records, patients with abnormal EEGs had a significantly higher BUN and Cl and lower Ca, as determined by standard (absolute) mean values. With relative changes, based on the percentage change from the previous value, the BUN, Ca, Cl, K, PO4 and CO2 showed significant relationships with a deteriorating EEG and the Ca, Cl, K and CO2 with an improving record. A deteriorating EEG was usually associated with an increasing BUN, Cr, K, Cl and Na and a decreasing Ca, PO4, Hct, Alb and CO2. Significant absolute changes in the chemical indices were more often seen than relative ones, especially with a deteriorating EEG. With either absolute or relatives values, the BUN showed the closest relationship with EEG deterioration and the Cr, Cl and Hct with EEG improvement. Changes were often seen in a combination of chemical indices, most often involving the BUN and to a lesser extent the Cr. With combined changes the one with the greatest change was especially the BUN and PO4. Variations in the amount of epileptiform activity were most closely related to changes in the BUN. The main conclusions of this study are that the BUN correlated best with the EEG among the 10 different serum values using various indices, especially standard (absolute) values with a deteriorating recording. The second highest number of correlations were found with the Cl, especially absolute values with an improving EEG. The Ca and K showed the best correlation with relative changes. Thus, correlations of various chemical indices with electrographic changes in uremic patients depend upon whether absolute or relative values are used and whether EEGs are deteriorating or improving.

Blood Urea Nitrogen↗
PubMed1995

Clinical correlations: MRI and EEG.

Main structural correlates of epileptogenesis include hippocampal sclerosis, cortical dysgenesis, foreign tissue lesions, gliosis, and dual pathology (a combination of any two). These structural abnormalities are now increasingly defined with MRI, enabling systematic EEG correlative analyses. Hippocampal atrophy (HA) and increased T2 signal in medial temporal structures predict the presence of mesial temporal sclerosis with a high degree of sensitivity and specificity. In 50 patients with clinical evidence of temporal lobe epilepsy and isolated HA, ictal scalp EEG was concordant to the atrophic temporal lobe in 33, nonlateralizing in 12, obscured in 3, and bilateral in 2, but it was discordant in none. Earlier reports of higher levels of discordance may be ascribed to the presence of dual pathology or to differing MRI and EEG criteria for localization. In a more inclusive group of 101 patients with unilateral HA, ictal scalp EEG was obtained in 99. It was unlocalized in 53, localized elsewhere in 9, and localized to the atrophic temporal lobe in 38. Of those, 51 patients had intracranial EEG: 12 were unlocalized, 29 were localized to the atrophic hippocampus, and 9 were localized elsewhere. There is thus a rare but definite subgroup of patients with unilateral HA who have EEG localization elsewhere than the atrophy. The successful cure of seizures in half these patients after removal of the EEG focus confirms the importance of this observation and emphasizes the search for more dual pathology that has remained undetected on MRI. About 10% of the patients with HA have significant atrophy bilaterally, and several series have confirmed that surgical success is predicted by removal of the EEG identified seizure onset area, not the more or less atrophic hippocampus. In patients with other kinds of dual pathology, including HA and foreign tissue lesions or cortical dysgenesis, EEG is also paramount in predicting the site of epileptogenesis for surgical intervention. EEG correlates of cortical dysgenesis are heterogeneous, but EEG has potential to provide accurate localization of the site of epileptogenesis in foreign tissue lesions also. In a study of 59 lesional patients, a small number of patients with low grade astrocytomas and oligodendrogliomas consistently localized by EEG to an area elsewhere than the lesion, and failed seizure control when the lesion was removed. Although MRI can demonstrate the structural correlate of the epilepsy in many situations, rare patients, particularly with certain tumors, cortical dysgenesis, and dual pathology, require EEG for accurate localization.

Atrophy↗
PubMed2006

The effect of CNS activation versus EEG arousal during sleep on heart rate response and daytime tests.

OBJECTIVE: To induce a heart rate change in normal subjects using auditory stimulation without inducing EEG arousals and to assess the effects on daytime functioning and compare results to auditory stimulation leading to short EEG arousals. METHODS: Six normal young men initially randomized into two groups (A and B) underwent 4 nights of nocturnal polysomnography (normal sleep on night 1, auditory stimulation without EEG arousal or normal sleep on nights 2 and 3 using Latin square design, and auditory stimulation with EEG arousal on night 4). MSLT and PVT were performed during days following nights 2-4. RESULTS: MSLT and PVT results showed significant differences after EEG arousal compared to stimulation without EEG arousal and to normal sleep; there were no significant differences after normal sleep compared to stimulation without EEG arousal. RR interval showed significant differences during undisturbed sleep compared to stimulation without EEG arousal and to stimulation with EEG arousal; RR interval without EEG arousal also differed significantly from RR interval with EEG arousal. CONCLUSION: Activation of the brain-stem can lead to autonomic nervous system (ANS) response without objective consequences the next day. SIGNIFICANCE: ANS responses induced by auditory stimulation during sleep without EEG arousal do not have the same effects on daytime sleepiness and performance as sleep fragmentation associated with EEG arousals.

Acoustic Stimulation↗
PubMed1998

Automatic EEG analysis during long-term monitoring in the ICU.

To assist in the reviewing of prolonged EEGs, we have developed an automatic EEG analysis method that can be used to compress the prolonged EEG into two pages. The proposed approach of Automatic Analysis of Segmented-EEG (AAS-EEG) consists of 4 basic steps: (1) segmentation; (2) feature extraction; (3) classification; and (4) presentation. The idea is to break down the EEG into stationary segments and extract features that can be used to classify the segments into groups of like patterns. The final step involves the presentation of the processed data in a compressed form. This is done by providing the EEGer with a representative sample from each group of EEG patterns and a compressed time profile of the complete EEG. To verify the above approach, 41 6 h EEG records were assessed for normality via the AAS-EEG and conventional EEG approaches. The difference between the overall assessment via compressed and conventional EEG was within one abnormality level 100% of the time, and within one-half level for 73.6% of the records. We demonstrated the feasibility and reliability of automatically segmenting and clustering the EEG, thus allowing the reduction of a 6 h tracing to a few representative segments and their time sequence. This should facilitate review of long recordings during monitoring in the ICU.

Child↗
PubMed2001

Ultradian rhythms of alternating cerebral hemispheric EEG dominance are coupled to rapid eye movement and non-rapid eye movement stage 4 sleep in humans.

Objective: To replicate the left minus right (L-R) hemisphere EEG power shifts coupled to rapid eye movement (REM) and non-rapid eye movement (NREM) sleep observed in 1972 by Goldstein (Physiol Behav (1972) 811), and to characterize the L-R EEG power spectra for total EEG, delta, theta, alpha and beta bands.Background: Ultradian alternating cerebral hemispheric dominance rhythms are observed using EEG during both waking and sleep, and with waking cognition. The question of whether this cerebral rhythm is coupled to the REM-NREM sleep cycle and the basic rest-activity cycle (BRAC) deserves attention.Methods: L-R EEG signals for ten young, normal adult males were converted to powers and the means were normalized, smoothed and subtracted. Sleep hypnograms were compared with L-R EEGs, and spectra were computed for C3, C4 and L-R EEG powers.Results: Significant peaks were found for all C3, C4 and L-R frequency bands at the 280-300, 75-125, 55-70 and 25-50 min bins, with power dominating in the 75-125 min bin. L-R EEG rhythms were observed for all bands. Greater right hemisphere EEG dominance was found during NREM stage 4 sleep, and greater left during REM for total EEG, delta and alpha bands (Chi-squares, P<0.001). Theta was similar, but not significant (P=0.163), and beta was equivocal.Conclusions: Earlier ultradian studies show that lateral EEG and L-R EEG power have a common pacemaker, or a mutually entrained pacemaker with the autonomic, cardiovascular, neuroendocrine and fuel-regulatory hormone systems. These results for L-R EEG coupling to sleep stages and multi-variate relations may present a new perspective for Kleitman's BRAC and for diagnosing variants of pathopsychophysiological states.

Journal Article↗
PubMed2005

Analysis and correction of ballistocardiogram contamination of EEG recordings in MR.

PURPOSE: To examine the influence of cardiac activity-related head movements and varying blood pulse frequencies on the shape of electroencephalography (EEG) recordings in a high magnetic field, and to implement a post-processing technique to eliminate cardiac activity-related artifacts. MATERIAL AND METHODS: Respiratory thoracic movements, changes of blood pulse frequency and passive head movements of 20 healthy subjects were examined outside and inside an MR magnet at rest in a simultaneously recorded 21-channel surface EEG. An electrocardiogram (ECG) was recorded simultaneously. On the basis of the correlation of the left ventricular ejection time (LVET) with the heart-rate, a post-processing heart-rate dependent subtraction of the cardiac activity-related artifacts of the EEG was developed. The quality of the post-processed EEG was tested by detecting alpha-activity in the pre- and post-processed EEGs. RESULTS: Inside the magnet, passive head motion but not respiratory thoracic movements resulted in EEG artifacts that correlated strongly with cardiac activity-related artifacts of the EEG. The blood pulse frequency influenced the appearance of the cardiac activity-related artifacts of the EEG. The removal of the cardiac activity-related artifacts of the EEG by the implemented post-processing algorithm resulted in an EEG of diagnostic quality with detected alpha-activity. CONCLUSION: When recording an EEG in MR environment, heart rate-dependent subtraction of EEG artifacts caused by ballistocardiogram contamination is essential to obtain EEG recordings of diagnostic quality and reliability.

Adult↗
PubMed2001

Localizing acute stroke-related EEG changes: assessing the effects of spatial undersampling.

Because of its sensitivity to metabolic and ionic disturbances related to ischemia, the EEG can be a potentially useful tool for acute stroke detection and for monitoring affected tissue. However, the clinical use of the EEG in detecting stroke is determined in part by how accurately the spatial information is characterized. The purpose of the current study was to determine the effects of spatial undersampling on the distribution and interpretation of the stroke-related topographic EEG. Using a 128-channel sensor montage, EEG was recorded from six stroke patients acutely (between 8 and 36 hours) after symptom onset. The EEG was submitted to a spectral analysis and was compared with patient symptoms and MRI and computed tomographic findings. To determine loss of spatial and clinical information resulting from spatial undersampling, the average-referenced data from the original 128-channel recording montage were subsampled into 64-, 32-, and 19-channel arrays. Furthermore, the analytical findings were compared with a board-certified electroencephalographer's review of the raw EEG using a conventional clinical montage. As predicted, the results showed that accurate description of stroke-related topographic EEG changes is dependent on adequate spatial sampling density. Accurate description of the spatial distribution of the stroke-related EEG was achieved only with the 64- and 128-channel EEG. As the recording density decreases to 32 channels, the distribution of the scalp EEG spectra is distorted, potentially resulting in mislocalization of the affected region. Results of the clinical review by an expert electroencephalographer corroborated the quantitative analyses, and the results also demonstrated the shortcomings of the conventional 10-20 recording density for capturing focal EEG abnormalities in several cases. The EEG provides useful information about the localization of acute cerebral ischemia, but recording densities of 64 channels or higher are required for accurate spatial characterization of focal stroke-related EEG changes.

Adult↗
PubMed1994

Developing of EEG print and its preliminary technical application.

In this report, we discuss a method called "EEG print" to represent EEG contrast mapping in time and frequency domains simultaneously. A bank of bandpass FIR (Finite Impulse Response) digital filters is used to obtain EEG prints. EEG prints were taken from four areas (F3, F4, O1 and O2) of EEG when healthy subjects were at rest with their eyes closed. The pattern of the prints was classified into four types: alpha type, beta type, alpha + beta type and complex type. It was found that EEG prints may vary from person-to-person but they usually do not vary much between the four areas for a given person. The method is further modified to obtain "differential EEG prints" to investigate whether meaningful higher frequency EEG components exist. Differentiation of EEG resulted in marked intensification of the fast waves, using 0.14 Hz as the critical point. In differential EEG print with higher order differentiation, amplification in the high frequency components increase their frequency. As a result, it is possible to observe variations in the high frequency components, which are otherwise not detectable in the usual EEG print. EEG print can be used for representing the function of the brain. Using the method for classification of EEG print patterns, described in this paper, we can clarify not only the characteristics of the normal brain but also the pathophysiology of mentally-ill patients.

Alpha Rhythm↗
PubMed1987

Transient neocortical, hippocampal and amygdaloid EEG silence induced by one minute inhalation of high concentration CO2 in swine.

The study is part of a series of investigations performed with the ultimate goal of obtaining an objective evaluation of the ethical aspects and the narcotic efficiency of CO2 inhalation used as pre-slaughter anaesthesia for swine. Six Yorkshire swine were exposed twice to 80% CO2 for 1 min during simultaneous recording of the EEGs from the frontal neocortex, the dorsal hippocampus, and the amygdaloid region via permanently implanted electrodes. In five of the animals myoclonic jerks started at 28 +/- 1 s of CO2 exposure and lasted for 6 +/- 2 s. Neocortical slow wave (delta) activity and increased amplitude of the hippocampal theta (5-7 Hz) waves (i.e. EEG changes seen during the second stage of barbiturate anaesthesia) had developed before the brief period of myoclonic jerks. After this period the EEG activity gradually declined, resulting in neocortical EEG silence at the end of the exposure. This apparent isoelectricity lasted for on average 1 min. The return of the neocortical EEG activity exhibited a pattern reverse to its disappearance, but was much prolonged in comparison to the EEG extinction. Pre-exposure neocortical EEG pattern was not regained until 3-5 min post-exposure. In eight out of 11 experiments the CO2 inhalation also induced hippocampal EEG silence lasting for on average 30 s. EEG flattening was further obtained when recording from the amygdaloid nuclear complex and the adjacent pyriform cortex. The observed changes in the neocortical and hippocampal EEGs suggest that the present swine were unconscious already when they exhibited motor reactions. This does not exclude the possibility that CO2-independent stress/arousal factors present in a slaughterhouse environment may facilitate the development of motor phenomena similar to seizures, with the result that such reactions become manifest before the neocortical EEG exhibits an anaesthesia pattern. The duration of the observed EEG silence implies that, from the ethical point of view, exsanguination might safely be performed within 1 min after the moment when the animal is removed from the high concentration CO2. However, the slow return to a pre-exposure neocortical EEG pattern suggests that the swine remains unconscious for at least another minute.

Amygdala↗
PubMed2003

Meta-analysis of EEG test performance shows wide variation among studies.

BACKGROUND: EEG results are used for counseling patients with seizures about prognosis and deciding on medications. Published sensitivities of interictal EEG vary widely. OBJECTIVE: To account for variation in test characteristics between studies. METHODS: Meta-analysis. Medline search, 1970 to 2000, of English language studies. Standard methods for meta-analysis of diagnostic test performance were used to determine the ability of EEG results to distinguish between patients who will and will not have seizures. Using linear regression, the authors assessed the influence of readers' thresholds for classifying the EEG as positive, sample probability of seizure, percent of subjects with prior neurologic impairment, percent treated, and years followed. RESULTS: Twenty-five studies involving 4,912 EEG met inclusion criteria. Specificity (range 0.13 to 0.99) and sensitivity (range 0.20 to 0.91) of epileptiform EEG interpretations varied widely and were heterogeneous by chi(2) analysis (p < 0.001 for each). Diagnostic accuracy of EEG and the thresholds for classifying EEG as positive varied widely. In the multivariate model, differences in readers' thresholds accounted for 37% of the variance in EEG diagnostic accuracy, and no other reported factors were significant. CONCLUSION: This analysis suggests that there is wide interreader variation in sensitivity and specificity of EEG interpretations, and that this variation influences the ability of EEG to discriminate between those who will and will not have seizure recurrences. In clinical practice, interpreting the degree to which a positive EEG result predicts increased seizure risk in an individual patient is difficult. Interpreting EEG with higher specificity yields more accurate predictions.

Adult↗
PubMed1991

[EEG data filing system with personal computer and magneto-optical disc].

We established a new computerized EEG filing system, in which an EEG machine was connected to an EEG filing unit which consisted of a personal computer with a 32 bit CPU, 18 channel analog -to-digital and digital-to-analog converters, and a magneto-optical disc driver. This system has the following merits. The system was space-saving, the space required to store the EEG data, being only 1/500 of that required for storing EEG record. Though the system had two independent EEG filing units, our original file configuration enabled us to have access to all of the recorded EEG data anytime for more than 10 years. The system enabled us to display EEG data continuously on the high resolution CRT, just as if turning the page of an EEG record paper, and through the quick scanning, enabled us to view the entire EEG pattern. Furthermore, the system enabled us to conduct reliable digital analysis for EEG data by entering the EEG data without artifacts into a data processor after confirmation on the display. In the system, we used data files with the MS-DOS operating system. This enabled us to analyze the data obtained by a personal computer operating on other systems, by transferring the data to a floppy disc operating on our system. Our EEG filing system allows quick access to data as well as mass data storage.

Electroencephalography↗
PubMed1986

[Principles and significance of genetically-induced variability of the normal human EEG].

This review describes the following results of human genetic research on the "normal" human EEG: As shown by comprehensive studies on mono- and dizygotic twins, interindividual variability of the human EEG under "normal" conditions is largely genetically determined. This was mainly shown for the resting EEG, but holds true also for the sleeping EEG, the reaction to ethanol, and for visually and auditory evoked potentials. Some fairly common EEG variants have been described which follow simple Mendelian modes of inheritance. Hence, they must go back to correspondingly simply differences in certain genes and gene-determined proteins. These variants have been useful as model systems for a neurobiologically founded research strategy in behaviour genetics of man. Comparative studies using psychological, neurophysiological (visual and auditory evoked potentials) and biochemical methods revealed group difference especially between carriers of the low-voltage EEG, the EEG with monomorphic alpha-waves and an EEG variant containing, in addition to alpha-waves, numerous diffuse beta-waves. Utilizing concepts from basic research in neurophysiology, they could be explained by corresponding differences in central information processing. Individual differences of EEG reaction are also observed after a controlled ethanol load. They have a genetic basis, too. An especially clearcut reaction of the EEG to alcohol can be seen in individuals with irregular alpha-activity of low amplitude in the resting EEG. Moreover, these persons appear to be especially susceptible for "learning" to become alcohol addicts. Individual variability in maturation during childhood and youth of brain structures responsible for EEG production are also under genetic control. This EEG maturation influences intellectual and psychic maturation.

Alpha Rhythm↗
PubMed1993

[Clinical study on judgement of brain death by the nasopharyngeal lead with the aid of an automatic EEG analysis system].

We investigated the relationship between scalp electroencephalogram (EEG) and nasopharyngeal EEG using Automatic EEG Analysis System in 10 patients with the age between 17 and 66 who were clinically presumed brain death because of flat line EEG and loss of auditory brainstem response (ABR). Among 10 patients, nasopharyngeal lead EEG showed low voltage and slow waves of 10-20 microV in 4 cases and flat line EEG in 6 cases. However, Automatic EEG Analysis system-assisted analysis of EEGs recorded on a magnetic tape revealed that equivalent electric potentials in the scalp EEG from these patients were smaller than those of healthy volunteers, but those in the nasopharyngeal EEG from all patients showed low voltage within the range of distribution in normal volunteers (delta:6, theta 1:6, theta 2:2, alpha 1:1, alpha 3:10, beta 1:6 in 10 cases). The present results show that in addition to the routine scalp EEG, it is clinically useful to employ simple and easy nasopharyngeal lead EEG method and to analyze data using Automatic EEG Analysis System for the judgement of brain death.

Adolescent↗
PubMed1993

[A quantitative pharmaco-EEG study on psychotropic properties of cerebral metabolic enhancers: comparison between young and elderly healthy volunteers].

In order to investigate psychotropic properties of cerebral metabolic enhancers (CMEs), the author carried out two identical quantitative pharmaco-EEG studies in different age groups of healthy volunteers; the young group (group-Y) consisted of six males between the ages of 21-26 years and elderly group (group-E) consisted of six males between the ages of 60-66 years. The drugs tested were five CMEs, dihydroergotoxine mesylate (DHE), propentofylline (PPF), nicergoline (NCG), lisuride maleate (LIS) and ibudilast (IDL). Each volunteer received either of the five test drugs or inert placebo in six one-day weekly sessions' according to single-blind, randomized crossover design. In each session, a single oral dose, equivalent to the clinically recommended daily dose, of either drug or placebo was administered and EEGs were recorded before and 1.3 and 6 hours after the drug administration. Firstly, the background EEGs before the drug administration were compared between the two groups. Group-E showed less slow activities and more alpha and fast activities than group -Y. This difference in background EEG profiles between two groups are considered to be due to physiological aging process. Secondly, drug effects on EEGs in two groups were compared. There were discrepancies in drug-induced EEG changes between the groups. In group-Y, any of the five tested CMEs did not induce EEG changes that were significantly different from placebo, whereas, in group-E, drug-induced EEG changes were more apparent. In group-E, DHE and PPF induced similar EEG changes, which were characterized by a decrease of alpha activity associated with marked decreases of slow and fast activities, the EEG profile similar to thymoleptics with sedative effects. LIS and IDL induced a decrease of alpha activity and an increase of fast activities, the profile close to thymoleptics with mood-elevating (stimulant) effects. NCG induced an increase of slow activities, the profile close to central depressants. These results in this study coincided with the experimental and subjective classification of the clinical effects of CMEs. Further analysis of EEG profiles based on principal component analysis indicated that there were two major components in background EEGs. There were discrepancies in the response to CMEs between two groups. In group-Y, CME-induced changes were seen mainly in the second principal component, while in group-E, the changes were seen mainly in the first principal component. These results suggested CMEs provoked thymoleptic effects by affecting the essential component of the EEG basic rhythm.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

The time course of sigma activity and slow-wave activity during NREMS in cortical and thalamic EEG of the cat during baseline and after 12 hours of wakefulness.

The extrapolation from recent neurophysiological findings concerning the dependency of spindle and slow-wave oscillations of thalamocortical neurons on membrane potential to macroscopic EEG events, predicts a reciprocal relation between spindle activity and slow-wave activity (SWA) in thalamic and cortical EEG during non-rapid-eye-movement sleep (NREMS). To test this hypothesis, the EEG recorded in 8 cats, from the nucleus centralis lateralis of the thalamus and from the skull during a 12-h baseline dark period and during a 12-h recovery dark period, following a 12-h sleep deprivation, were analyzed. Per 12-s epoch, sleep-wake behaviour was determined and spectral power density was computed in the slow-wave frequency range (0.5-4.0 Hz) and in the spindle frequency region (sigma activity: 11.0-14.5 Hz). To analyze the development of EEG power densities in the course of NREMS and during the transition from NREMS to REMS, the last epoch of wakefulness and the first 15 epochs of NREMS, as well as the last epochs of NREMS and the first epoch of REMS were selected from the NREM-REM cycles. For each animal the values were averaged over 4-h intervals. In the cortical EEG, SWA was minimal at NREMS onset and increased progressively in the course of NREMS. SWA declined sharply prior to REMS. sigma Activity increased gradually towards a uniform level after NREMS onset. During the transition to REMS, sigma activity initially increased and then decreased rapidly. In the thalamic EEG, the time course of SWA paralleled that of the cortex. However, the development of sigma activity during the first part of NREMS differed: in the thalamic EEG, sigma activity was maximal during the beginning of NREMS and slightly decreased thereafter. After sleep deprivation, SWA within NREMS was markedly enhanced in both the cortical and the thalamic EEG. Sigma activity was attenuated in the thalamic EEG, whereas in the cortical EEG it was temporarily elevated. The present data show that, in the thalamic EEG, an inverse relation exists between spindle and slow-wave activity during baseline NREMS. This relation is preserved after sleep deprivation. In the cortical EEG, a reciprocal relation between spindling and SWA is less evident.

Animals↗