Clinical EEG (electroencephalography)最新文献

Respiratory compromise is not uncommon in epileptic seizures. However, pure apneic seizures are rare. In this study, we report 10 children who presented with pure apneic seizures. All the children were admitted because of apneic events. Seizures were also considered in the differential diagnosis. Six patients had nonspecific findings consisting of multifocal interictal epileptiform activity with no event correlation. Continuous 24-72 hours electroencephalogram (EEG) was performed in all patients to rule out apneic seizures. Ictal EEG showed high correlation with the apneic episodes, confirming the diagnosis of apneic seizures. Our study suggests that continuous EEG monitoring is essential in the diagnosis and treatment of apneic seizures.

The purpose of this study was to investigate the duration of monitoring, number of seizures recorded, and date and time of occurrence of seizures in different patient groups during video-EEG monitoring (VEEGM). Patients with partial or psychogenic seizures who were admitted to our VEEGM unit between September 1996 and March 2002 were retrospectively evaluated. Duration of monitoring, date and time of occurrence of seizures were identified in each patient. For practical reasons, a day was divided into 3 equal time periods (period 1: 08-16; period II: 16-24 and period III: 24-08 hrs), and the period in which the seizure occurred was noted. Patients were classified in 5 groups: 1-temporal; 2-frontal; 3-parieto-occipital; 4-psychogenic and 5-unclassified. Duration of monitoring, the number of seizures recorded and time distribution of seizures were identified in each group and compared statistically. We evaluated 746 seizures in 209 patients. Seizures were more likely to occur in periods I and III in groups 1 (p = 0.004) and 5 (p < 0.001). In group 4 they were more likely to occur in periods I and II (p < 0.001). Duration of monitoring was not statistically different between the groups. However, the number of seizures recorded varied significantly (p = 0.006). Patients in group 5 had the greatest number of seizures and were followed by groups 2, 4, 3 and 1, respectively. Groups also differed according to date of seizure occurrence (p < 0.001). We conclude that the number of seizures recorded and time distribution of seizures during VEEGM are influenced by the lobe of onset of seizures.

The P300 event-related brain potential (ERP) was examined in 14 young (20 - 29 years of age) and 16 elderly (60 - 82 years of age) adult subjects during the performance of auditory and visual discrimination tasks requiring silent counting or key pressing in response to target stimuli. P300 latencies were longer in elderly (vs young) adults and in visual (vs auditory) tasks, and visual tasks elicited larger P300 amplitudes than auditory tasks in both age groups. Neither stimulus modality nor response mode affected P300 differentiation of young and elderly subjects. Steeper P300 anterior-posterior scalp amplitude gradients were seen in the young (vs elderly) adults, regardless of stimulus or response type. Examination of inter-subject variability with the coefficient of variation (CV) statistic found the lowest (i.e., best) CV values to be exhibited in the visual task requiring the counting of target stimuli. Implications of the findings are discussed in relation to P300 applications in the clinical assessment of dementia and aging-associated cognitive alterations.

To investigate sequential changes in electroencephalograms (EEGs) during intermittent photic stimulation (IPS), quantitative EEG analysis for the alpha band (related to stimulus frequency) was performed in 18 drug-naïve schizophrenic patients and 18 sex- and age-matched control subjects. IPS consisted of white flickers at 10 flashes/sec, lasting 10 sec and repeated six times at 10 sec intervals. The differences between the two groups were assessed for two conditions (i.e., during photic stimulation (PS) and inter-PS). During stimulus, the absolute 9-11 Hz band power of the patient group was higher at the posterior than that at the anterior sites throughout the 10 sec periods. However, this difference between sites was not seen during the first 1 sec in the control group. During the nonstimulus period, posterior dominance of 9-11 Hz band power was prominent in the patient group throughout. In the control group, however, this difference was minor, especially during the latter half of the period. These results suggest that schizophrenic patients show fewer changes in posterior alpha activity during both stimulus and nonstimulus, and this continuity of posterior dominance may reflect hyperarousal, which counteracts any decrease in vigilance throughout the IPS.

We developed a device to record olfactory event-related potentials (OERP) from the human scalp. Methyl-cyclopentenolone was used as the odorant element. A total of 50 stimuli were delivered. Each stimulus lasted 0.5 sec and was delivered once every three inspirations. Normal OERPs were obtained with this device. The positive peak latencies were approximately 350 msec (P1) and 700 msec (P2), respectively. OERPs were also recorded in 40 patients with smell disorders. A positive response at about 300-400 msec was recorded in 7 patients (all females, 15-59 years old). The other 33 patients showed no response. The high potential area of this positive peak was located in the centro-occipital region of the scalp. The latency and the high potential area of this peak were similar to P1 recorded in normal subjects. The source of this peak was considered identical to that of P1. This may be a response to the trigeminal nerve during odor administration. P2 was not recorded in the patients with smell disorders. P2 may therefore be a response to the olfactory nerve.

It has been reported that the rolandic area generating spikes is hyperexcitable, and that rolandic spikes propagate across the central area. However, the pattern of rolandic spike propagation and how the dipolar distribution of the spikes is related to the propagation pattern have not yet been studied. Thirty-nine EEGs from 27 patients with benign rolandic epilepsy (BRE) were examined. Sequential topographic mapping in 4-ms steps was used to analyze the pattern of spike propagation. The locations of maximum negative foci, the presence and distribution of the dipolar field, and the propagation pattern were examined. Dipoles were present in 23 (85.2%) out of 27 patients and in 43 (72.9%) out of 59 foci. Thirty-two foci (54.2%) in 20 patients demonstrated a propagation pattern. The typical pattern consisted of propagation from central to mid-temporal locations across the central sulcus. Most spike foci exhibiting a propagation pattern had a dipolar distribution (87.5%; p=0.008). These results suggest that rolandic spikes originate from sulcal or gyral cortices on either side of the central sulcus, and that spike propagation can ensue by intracortical spreading across the central sulcus.

To determine if P300 latency changes precede and correlate with memory and mental status, patients (N=1506 aged 20-100 years) who received medical and psychiatric diagnoses (from 1997 to 2002), were assessed for P300 (N=1496), WMS-III (N=694), and MMSE (N=456). Patient and control groups included, a) normal WMS-III on all 4 subscales (N=36), b) normal WMS-III and MMSE (N=189) with subjective memory/mental status complaints, and c) medical patients with normal WMS-III and no memory complaints (N=205), and d) P300 control group without medical, psychiatric or memory problems for ROC. Patients with impaired/borderline memory had a prolonged P300 latency (P<0.02) compared to age matched non-impaired controls; in patients with normal WMS-III/MMSE, with subjective mild memory/mental status impairment, P300 latency was prolonged compared to controls (P=0.0004). The P300 latency increased by 0.72ms per year (P=7.9x10(-65)) and voltage decreased by 0.03dV per year (P=6.7x10(-10)), and both parameters were linearly correlated with the age of the subjects. Male subjects had an average voltage of 6.1dV and female 6.8dV (P=0.00009). Statistically, prolonged latency began at age range 41-50 (P=0.0002); reduced P300 voltage began at age range 51-60 (P=0.003). WMS-III memory decline for all measures began in females at age range 61-70 (P value at least=0.02) and for males at age range 61-80 (P=0.02). Prolonged P300 latency (P<0.0001) and memory impairment (at least <0.02) were greater for females than males. MMSE memory decline, male and female, began at age range 81-90 (P value of at least 0.00007). In our logistic regression model P300 latency was more predictive of WMS-III impairment than MMSE > 24. In patients whose WMS-III score is impaired < or = 69, or borderline < or = 79 (P at least=0.004), a P300 latency more prolonged than the norm (> or = 300 + 30 + Age) identifies these patients, whereas a MMSE > 24 failed. With the ROC curve, we confirmed that P300 latency could accurately identify borderline/impaired memory.

Neurofeedback (NFB) is an operant conditioning procedure, by which the subject learns to control his/her EEG activity. On one hand, Learning Disabled (LD) children have higher values of theta EEG absolute and relative power than normal children, and on the other hand, it has been shown that minimum alpha absolute power is necessary for adequate performance. Ten LD children were selected with higher than normal ratios of theta to alpha absolute power (theta/alpha). The Test Of Variables of Attention (TOVA) was applied. Children were divided into two groups in order to maintain similar IQ values, TOVA values, socioeconomical status, and gender for each group. In the experimental group, NFB was applied in the region with highest ratio, triggering a sound each time the ratio fell below a threshold value. Noncontingent reinforcement was given to the other group. Twenty half-hour sessions were applied, at a rate of 2 per week. At the end of the 20 sessions, TOVA, WISC and EEG were obtained. There was significant improvement in WISC performance in the experimental group that was not observed in the control group. EEG absolute power decreased in delta, theta, alpha and beta bands in the experimental group. Control children only showed a decrease in relative power in the delta band. All changes observed in the experimental group and not observed in the control group indicate better cognitive performance and the presence of greater EEG maturation in the experimental group, which suggests that changes were due not only to development but also to NFB treatment.

There is need nowadays to re-emphasize the capabilities of electroencephalography: a method representing the extremely important function/dysfunction-orientation in neurological thinking and practice. Valuable and relevant messages to the clinician naturally require solid EEG training and the resulting expertise. The idea that valuable EEG information is limited to the field of epileptology is erroneous. A plethora of clinically relevant messages can be derived from the EEG in nonepileptic conditions and, above all, in metabolic (and so called "mixed") encephalopathies where neuroimaging has almost nothing to offer. The discussion of EEG and epileptology only skirts pediatric conditions (and most of the epileptic syndromes). It is shown that EEG reading in epileptology is a lot more than simply "hunting spikes." A strong plea is being made against the presently fashionable overuse of the term "non-convulsive status epilepticus." Continuing neglect of functional/dysfunctional orientation can seriously endanger the entire field of Neurology.

Studies on the predictive value of the electroencephalogram (EEG) concerning the risk of seizure recurrence have shown contradictory results. We prospectively studied the predictive value of the standard EEG and EEG with sleep deprivation for seizure relapse in adult patients presenting with a first unprovoked seizure. EEGs were performed on 157 adult patients within the first 48 hours of the first seizure. Additional EEGs with sleep deprivation were obtained in 60 cases. The standard EEG was abnormal in 70.7% and significantly associated with an increased risk of seizure recurrence [risk ratio 4.5, 95% confidence interval (CI) 1.8; 11.3, p=0.001]. Subgroup analysis revealed the highest recurrence rates for patients with focal epileptiform activity (risk ratio 2.2, CI 1.2; 4.2, p=0.01). EEGs with sleep deprivation were abnormal in 48.3% of all cases and revealed epileptiform discharges in 13.3% of the patients who had no epileptiform activity in the standard EEG. Routine EEG revealed abnormalities in 60 of 94 patients who presented with normal neurologic status on admission. Further neuroradiological examinations detected previously unknown brain lesions in 19 of these cases, particularly cerebrovascular disease (CVD, n=7), brain tumors (n=6), and posttraumatic scars (n=4). In conclusion, the EEG is important for the early detection of focal nonepileptic and epileptic abnormalities after a first unprovoked seizure in adult patients and may provide valuable information on previously unknown disorders, particularly CVD and cerebral tumors. The abnormal EEG is a highly significant predictor for seizure recurrence. An additional EEG with sleep deprivation is helpful in cases when standard EEG does not reveal epileptiform discharges.