Clinical EEG (electroencephalography)最新文献

EEG in epilepsy in the elderly (onset > 60 yrs) was investigated (161 patients--302 EEGs) and was compared to a group of younger patients (onset 20-59 yrs) matched for sex ratio (also 161 patients--296 EEGs). In the elderly, the frequency of the background rhythm was decreased, as was the rhythmicity and amplitude. Complex partial attacks were twice as often seen in the older group, but generalized tonic-clonic seizures were more than three times as often in the younger group. The major etiology in the elderly was cerebrovascular disease, but brain tumors were found in nearly one quarter, while head injury, drug abuse, and AVM were more often seen in the younger patients. The first EEG was positive for epileptiform activity in 83%, later at 92-93% in both groups, emphasizing adequate sleep records. Although temporal lobe abnormalities were most often seen, frontal lobe discharges and slow waves were significantly more often noted in the elderly. As an example of the prominence of epileptiform activity in some elderly, PLEDs and very many discharges were seen mainly in the older group, which less often showed only rare discharges.

This case illustrates a classic example of CJD in its clinical presentation and course and the EEG. It also shows dramatically the utility of a newly developed protein assay in the diagnosis of this disease. This assay has the potential of eliminating the need for brain biopsy in most cases, thus providing a safer diagnostic method for both staff and patients. In addition, the case points out that anatomical structural studies such as CT and MRI do not replace the utility of EEG in the comprehensive evaluation of rapid onset dementia, but rather complement the usefulness of EEG.

Theoretical models of higher cognitive function predict that cortical activity will exhibit families of spatial-temporal patterns of activity whose individual members are related to each other by specific symmetry transformations. In the trion model, it is suggested that these inherent symmetries play a vital role in how we think and reason. We have developed a method of analysis (SYMMETRIC analysis), which detects families of patterns in EEG data, and characterizes the symmetry relationships between members of those pattern families. Using this analysis, significant symmetry families have been found in EEG and single unit spike train data. If symmetry is a crucial aspect of brain function, it is possible that different pathologies are associated with specific types of symmetry relationships in brain activity that could be detected in EEG data by a SYMMETRIC analysis.

We studied clinical aspects of the "third rhythm," which was first described by Niedermeyer as alpha-like activity of the temporal lobe. By scalp EEG, temporal alpha-like activity was recorded in 15 (0.30%) of 4929 patients over 20 years of age. The temporal alpha-like activity was observed in 5 patients who had clinical and brain imaging findings indicating the presence of a cerebrovascular disorder. The alpha-like rhythm of these patients was left-sided, and wicket spikes appeared in the same region as the alpha-like rhythms in 4 of the 5 patients. In 8 of the 15, the temporal alpha-like rhythm was recorded over the defective bone or replacement bone after intracranial surgery. The alpha-like rhythm of these patients was similar to breach rhythm in the temporal region. The remaining 2 patients had not undergone intracranial surgery nor did they show symptoms of cerebrovascular disorders. The temporal alpha-like rhythms in one of these 2 might be a physiological third rhythm detected by scalp EEG through congenital bone thinning. Our observation supports the existence of intrinsic activity of the temporal lobe (the third rhythm). The third rhythm can be recorded by routine scalp EEG in some clinical conditions, and it is important to recognize this rhythm when one encounters temporal rhythmic activity independent of alpha rhythm of the occipital lobe.

Motivated by predictions from the structured trion model of the cortex, based on Mountcastle's columnar organizational principle, behavioral experiments have demonstrated a causal short-term enhancement of spatial-temporal reasoning in college students following listening to a Mozart Sonata (K.448) but not in control conditions. An EEG coherence study reported presence of right frontal and left temporoparietal activity induced by listening to the Mozart Sonata, which carried over into the spatial-temporal tasks in three of the seven subjects. In this paper, we present further predictions from the trion model and discuss how the new SYMMETRIC analysis method can be used in EEG recordings to help determine the neurophysiological basis of specific music enhancing spatial-temporal reasoning. We conclude with potential clinical applications of major significance.

The burst-suppression (BS) pattern of the EEG occurs in a rather limited number of conditions. It has been observed in deep stages of general anesthesia and in conjunction with sedative overdoses. It is also known to occur in the wake of cardiorespiratory arrest. Undercutting of the cortex has been found to result in BS activity. Rare neonatal epileptic encephalopathies also give rise to BS. Our personal interest was prompted by the consistent finding of BS activity in rats following cerebral anoxia (nitrogen inhalation, airway obstruction): after periods of EEG flatness, BS activity developed, followed by periodic bursts and diffuse slowing. On the other hand, earlier literature (before 1960) showed virtually no observation of BS, neither in anoxic patients, nor in animal experiments. It is likely that the introduction of modern intensive care treatment has engineered episodes of BS activity, probably due to modifications of the anoxic cerebral pathology.

Precipitation of spike and wave (SW) discharges in some epileptic patients by eye closure (EC) has rarely been reported. To disclose the clinical characteristics and classification of syndromes of epileptic patients with SW discharges induced by EC, we investigated 10 patients (1 M, 9 F) showing this peculiar EEG feature. The patients aged between 9-39 years (mean 20.6 +/- 9.058), underwent short-term (1-3.5 hr) video-EEG investigations in order to document the appearance of the SW discharges within 3 seconds of the act of EC, in at least two occasions. Clinical analysis showed that 5 female patients who had the syndrome of juvenile myoclonic epilepsy (JME) had a later onset of epilepsy (13-15 years) than the 3 patients (3 girls) with eyelid myoclonia with absences (EMA) (3-8 years of age at onset). The remaining 2 patients who were diagnosed as childhood absence epilepsy (CAE) and juvenile absence epilepsy (JAE) according to the international classification, did not show photosensitivity on the video-EEG. All but one of the 5 JME patients had experienced myoclonic seizures in intermittent photic stimulation (IPS) at the time of EC, associated with multiple spike and wave discharges. Two of the 3 EMA patients exhibited typical absences with eyelid myoclonia during the act of EC. The high rate of family history of epilepsy in first degree relatives of our patients was an outstanding feature, which could have future implications in research of the genetic basis of epilepsy patients with ECS.

Slow sharp waves (SSHW) are of longer duration (around 200 msec and longer) than typical sharp wave discharges (70 to 200 msec). This pattern is not merely of academic interest, as the electroclinical correlation showed that SSHW were found in 23 patients, mostly above age 50 years, with serious illnesses of various etiologies. Epileptic seizures occurred in a minority of the cases. The electrophysiological basis remains unclear and there is no answer to the question, "what causes the relatively long duration of these discharges?"

We report a case of Wilson's disease with circling seizures. Because of the existence of other types of frontal automatism and the EEG focus on the frontal regions, circling seizures of the patient were thought to originate from the frontal lobe. Magnetic resonance imaging demonstrated large cavitary lesions on bilateral frontal lobes. The mechanisms of circling behavior are discussed in association with Wilson's disease.