Clinical EEG (electroencephalography)最新文献

The EEG in this patient shows bilateral spike and wave complexes with a 3/sec component (anteriorly) simultaneously with the 6/sec form (posteriorly). The well established 3/sec form as an epileptiform pattern seen in absence seizures lends support for a significant relationship with the 6/sec form, which should not be dismissed as a "normal variant."

Long latency auditory evoked responses (AER) were formed to single tones and rapid tone pairs. Using the t-statistic SPM technique, children with poorer WIAT reading scores demonstrated group difference overlying the left parietal and frontal language regions but just for AER to tone pair stimuli. Variables derived from these regions were not significantly different when the same subjects were grouped by K-BIT Matrices scores. When the same children were regrouped by Matrices scores and compared using the SPM technique, differences were now seen over the right hemisphere, especially in the parietal and frontotemporal regions, for both single and two-tone derived AERs. Variables derived from these regions were not significantly different for children when grouped by reading score. AER data support a specific deficit in two-tone stimulation for poorer reading children over the left hemisphere and also a deficit to both single and two-tone stimulation over the right hemisphere for children with poorer Matrices scores.

A prospective study was conducted to assess the ability of the visually analyzed electroencephalogram (VEEG), the quantitative EEG (QEEG) and the Glasgow Coma Scale (GCS) to discriminate between patients with viral and nonviral meningitis. The 55 subjects, aged 14-75 years, fell into one of the following categories: viral (n = 12), bacterial (n = 19), tuberculous (n = 16) or cryptococcal (n = 8) meningitis. EEG recordings and Glasgow Coma Scale (GCS) scores were obtained within 48 hours of admission to hospital. The sensitivity of the VEEG and QEEG for the prediction of patients with nonviral meningitis (true positives in this context) attained reasonably high values of 70% and 80%, respectively. In contrast, the sensitivity of the GCS was only 38%. Each of the three tests achieved high degrees of consistency in this regard with positive predictive values of 94% or better. The specificity for each of the three tests was high, 100% for the VEEG and the GCS and 82% for the QEEG indicating a high probability for the correct prediction of viral meningitis (true negatives). The consistency of this prediction was, however, poor due to negative predictive values of only 53% for the QEEG, 48% for the VEEG and 32% for the GCS. The QEEG results did not reveal any obvious advantages over the VEEG. Rather the assessment of the occurrence of particular VEEG abnormalities showed that patients with delta abnormalities had a very high probability of nonviral meningitis. At the other end of the spectrum, all normal VEEGs occurred in viral meningitis. In important respects the predictive ability of the EEG was superior to that of the GCS. While there was statistically significant agreement between the VEEG and GCS, the degree of agreement was poor. This study indicates that the EEG is a valuable and probably underestimated test in the acute phase of meningitis and provides complementary information to the GCS.

To understand the relationship between subjective and objective indices of sleepiness, we studied the relationship of the Epworth Sleepiness Scale (ESS) and the Maintenance of Wakefulness Test (MWT) in 41 consecutive patients complaining of snoring and excessive day-time sleepiness. The correlation between ESS and MWT was significant but small (rho = -0.39). There was considerable discordance between the two tests. The Lowess fit line between the ESS and the MWT indicates that the ESS falls as the MWT rises to about 4 min. It then stays at a plateau until the MWT rises to about 12 min. Thereafter, it resumes its downward slope as the MWT rises further. Thus, in patients who are severely sleepy on the MWT, the ESS may not be sensitive to different levels of sleepiness. We conclude that the ESS and the MWT are not equally useful in assessing sleepiness in patients with sleep apnea.

We investigated whether total intravenous anesthesia with ketamine, fentanyl and droperidol would affect middle latency auditory evoked potentials and explicit memory, and whether dreams during the anesthesia are related to plasma concentrations of fentanyl and the infusion technique. A total number of 40 patients were the subjects for this study. Twenty patients (group A) were maintained with intravenous ketamine 2 mg kg-1 hr-1 and fentanyl 5 micrograms kg-1 hr-1 for the first 60 min and 3 micrograms kg-1 hr-1 for the next 90 min, and droperidol 0.1 mg kg-1. The remaining 20 patients (group B) were maintained with intravenous ketamine 2 mg kg-1 hr-1, droperidol 0.1 mg kg-1 and fentanyl 50-100 micrograms in a bolus intermittently as needed by vital signs such as increases in heart rate and arterial blood pressure. Middle latency auditory evoked potentials, plasma fentanyl and ketamine levels were measured; explicit memory and dreams were also estimated. There were no patients who recollected explicit memories of intraoperative events in both groups. The middle latency auditory evoked potentials were not significantly changed during the anesthesia in both groups. We could find no significant differences in latencies and amplitudes of the middle latency auditory evoked potentials between the both groups. Plasma fentanyl levels of group B patients were significantly lower than those of group A patients and the incidence of the dreams was significantly higher in group B patients. We conclude that the anesthesia with ketamine, fentanyl and droperidol is not associated with the explicit memories, though the middle latency auditory evoked potentials were not significantly changed as compared with those in the waking state. In addition, dreams during the anesthesia may correlate with plasma fentanyl concentrations or the infusion technique.

Quantitatively analyzed resting electroencephalographic (EEG) activity and P300 event-related potentials elicited with a passive tone sequence paradigm were examined in 30 patients with dementia of the Alzheimer type (DAT) and 15 age matched controls. Background electrical rhythms of DAT patients evidenced slowing as shown by increased absolute and relative amplitudes in slow frequency bands and decreased amplitudes in fast frequency bands (relative to controls). Electrical slowing was more evident in patients with higher clinical ratings of global intellectual deterioration. Passive P300 amplitude and latency did not differentiate patients and controls and were not related to severity of dementia.

The relationship of changes in intraoperative QEEG and postoperative cognitive function was studied in 32 patients undergoing cardiac surgical procedures requiring cardiopulmonary bypass (CPB). All patients were anesthetized with a high dose narcotic technique in which CPB was carried out using moderate hypothermia. EEG recorded continuously throughout each procedure was analyzed using the neurometric technique. Neuropsychological (NP) evaluations were administered to all patients before, 1 week and 2-3 months postoperatively. A decrement in postoperative performance of 2 standard deviations in two or more tests from preoperative testing was defined as a new cognitive deficit. Of the patients studied, 40.6% demonstrated a new postoperative cognitive deficit at 1 week. At 2-3 months postoperatively, 28.1% continued to show a cognitive deficit. Discriminant analysis of the QEEG as a function of NP performance was calculated at select times during the surgical procedure. QEEG prediction of NP performance was just above chance at the 1 week comparison but excellent for the 2-3 month comparisons. This study suggests that with appropriate monitoring protocols, intraoperative QEEG may predict cognitive dysfunction experienced by patients 2-3 months postoperatively.

The central motor conduction time (CMCT) was investigated in 12 cases of chronic alcoholism with frontal lobe atrophy, 12 cases of chronic alcoholism without frontal lobe atrophy, and 12 age-matched healthy controls. The CMCT was significantly prolonged in the chronic alcoholics with frontal lobe atrophy as compared to the chronic alcoholics without frontal lobe atrophy and the healthy controls. A significant positive correlation was noted between the CMCT and the degree of frontal lobe atrophy. The CMCT may be prolonged in chronic alcoholics with frontal lobe atrophy.

In routine clinical EEG, a common origin is assumed for delta and theta rhythms produced by brain lesions. In previous papers, we have provided some experimental support, based on High Resolution qEEG and dipole fitting in the frequency domain, for the hypothesis that delta and theta spectral power have independent origins related to lesion and edema respectively. This paper describes the results obtained with Frequency Domain VARETA (FD-VARETA) in a group of 13 patients with cortical space-occupying lesions, in order to: 1) Test the accuracy of FD-VARETA for the localization of brain lesions, and 2) To provide further support for the independent origin of delta and theta components. FD VARETA is a distributed inverse solution, constrained by the Montreal Neurological Institute probabilistic atlas that estimates the spectra of EEG sources. In all patients, logarithmic transformed source spectra were compared with age-matched normative values, defining the Z source spectrum. Maximum Z values were found in 10 patients within the delta band (1.56 to 3.12 Hz); the spatial extent of these sources in the atlas corresponded with the location of the tumors in the CT. In 2 patients with small metastases and large volumes of edema and in a patient showing only edema, maximum Z values were found between 4.29 and 5.12 Hz. The spatial extent of the sources at these frequencies was within the volume of the edema in the CT. These results provided strong support to the hypothesis that both delta and theta abnormal EEG activities are the counterparts of two different pathophysiological processes.