Clinical EEG (electroencephalography)最新文献

The original concepts of absence status (AS) and complex partial status (CPS) are critically reviewed. This review has been prompted by a modern concept of nonconvulsive status epilepticus (NCSE), portrayed as a rather common condition occurring chiefly in the critically ill elderly with high morbidity and mortality. This new view is a striking departure from the original concepts of AS and CPS as rare protracted epileptic events occurring usually in temporarily confused but otherwise satisfactorily healthy and ambulatory patients. This new trend appears to have been caused by a misinterpretation of EEG findings: prominent generalized spike activity is in reality the expression of a very severe encephalopathy rather than of NCSE, most often caused by an anoxic episode. The role of EEG is emphasized but a valuable interpretation depends on an expert integration of EEG and clinical data. A brief discussion of epileptic twilight states further stresses the difficult differential diagnosis.

In search of early neuroleptic response predictors in schizophrenia, functional interhemispheric and intrahemispheric asymmetry indices, derived from spectrally analyzed resting electroencephalographic (EEG) activity, were examined in 17 schizophrenic patients prior to open label treatment with the atypical neuroleptic clozapine. Compared to EEG asymmetry indices derived from a normative data bank, patients exhibited significant interhemispheric (left greater than right) and intrahemispheric (anterior greater than posterior) deviations in delta, theta, alpha and beta frequency bands. Intrahemispheric indices were positively correlated with clinical ratings of positive symptoms and global psychopathology. Clozapine-induced improvements in positive and negative symptoms and global psychopathology symptom ratings were related to pretreatment intrahemispheric asymmetry only, with relationships varying with symptom, recording region and frequency band. The results are discussed in relation to the neurobiology of schizophrenia and the utility of EEG as an informative predictor of treatment response.

There is no doubt that the frontal lobe plays a major role in the 3/sec spike-wave absence seizure. It is pointed out initially that the controversies of cortical vs. thalamic origin of the spike-waves and the associated absence can be laid at rest as far as human absence seizures and human primary generalized epilepsy (PGE) are concerned: their origin is cortical with maximal frontal lobe involvement. Experimentally-induced spike-wave bursts or spontaneous spike-waves in animals pertain to other forms of epileptic seizure disorder. The frontal maximum of the 3/sec spike-wave pattern indeed indicates maximal frontal lobe involvement including both prefrontal and frontomotor portions. The absence as such is presumed to be a suspension of the working memory--an eminently frontal lobe function. This explains the immediate restoration of ictally-impaired neurocognitive functions right at the termination of the seizures. This concept can be applied not only to the classical absence occurring in PGE but also to the rare cases of secondary bilateral synchrony with a primary frontal epileptogenic focus leading to true (though very slightly different) absences.

The aim of this study was to determine the performance of a PC-based system for real-time detection and topographical mapping of epileptiform activity (EA) in the EEG during routine clinical recordings. The system incorporates a mimetic stage to locate candidate spikes (including sharp-waves) followed by two expert-system-based stages, which utilize spatial and wide-temporal contextual information in deciding whether candidate events are epileptiform or not. The data comprised 521 consecutive routine clinical EEG recordings (173 hours). Performance was evaluated by comparison with three independent electroencephalographers (EEGers-I). A second group of two EEGers (EEGers-II) separately interpreted the spike topographical maps and, for EEGs categorized as containing only questionable EA by the detection system, reviewed 6 sec segments of raw EEG centered on each questionable event. Thirty-eight of the EEGs were considered to contain definite EA by at least two of EEGers-I. The false detection rate of the system was 0.41 per hour. The system was found to have a sensitivity of 76% and a selectivity of 41% for EEGs containing definite EA. However, it only missed detection of EA in 5% of the recordings. EEGers-II agreed with EEGers-I on the distribution (generalized, lateralized, focal, multifocal) of EA in 79% of cases. This is by far the largest clinical evaluation of computerized spike detection reported in the literature and the only one to apply this in routine clinical recordings. The false detection rate is the lowest ever reported, suggesting that this multi-stage rule-based system is a powerful and practical tool in clinical electroencephalography and long-term EEG monitoring.

We report a case of Jarisch-Herxheimer reaction in a patient with neurosyphilis, which was complicated by nonconvulsive status epilepticus. The EEG features suggested a focal seizure onset, although the patient's MRI was normal. JHR is common in the treatment of neurosyphilis, but usually produces only transient systemic constitutional symptoms. Neurologic deterioration is rare, but can be dramatic, as in our patient. NCSE should be considered as an explanation for persistent obtundation and transient focal neurologic findings in this setting.

Twenty-two patients with documented COPD and no other significant illnesses were studied to assess the effect of varying degrees of COPD on the intrinsic alpha rhythm. The severity of COPD was determined by spirometry with assessment of FEV1, FVC, and FEV1/FVC. The alpha frequency for COPD patients was slower than that which characterizes age equated normals and averages 1.6 S.D. below normative data base mean values (range -0.43 S.D. to -1.85 S.D.). Impairment of pulmonary functioning significantly correlated with the degree of alpha frequency slowing over the posterior cortical regions, and the slowest alpha frequencies occurred in those COPD patients with the lowest FEV1/FVC ratios. Impairment of cognitive functioning is thus an important clinical consideration in treatment of patients with COPD but may go unrecognized until late in the course of the disease.

The stimulating methods of prior studies on somatosensory evoked potentials (SEPs) elicited by acupoint stimulus had involved surface electrodes, while the clinical practice of acupuncture is mostly performed by inserting the acupuncture needle inside the body. Clinical observations show that there are often some special sensations when LI-4 is needled. To observe if the SEPs produced by acupoint acupuncture had a distinguishing property, we studied the SEPs elicited by electrical acupuncture after the acupuncture needle was inserted into LI-4 and its control point, and then mapped them with the 128-channel Electric Brain Signal Image system. We also compared this to SEPs by median nerve stimuli. Results showed that the most interesting finding was the marked differences of N1-P1 and N2-P2 amplitude between SEPs at LI-4 (SEP-LI) and its control point (SEP-CP), which were in the opposite direction. Marked differences were also found between latencies and amplitudes of the SEPs elicited by acupuncture and by median nerve stimulus (SEP-M). The differences between SEP-LI and SEP-CP might be due to the additional effects of the activation of nerve endings and muscle spindles in LI-4 to the SEPs formed by the activation of superficial and deep radial nerves during electrical acupuncture. The differences between SEPs to acupoint and median nerve stimuli might be mainly due to the different distances from the stimulated regions to the cerebral cortex, the diversity and the number of activated fibers.

Nose wiping is a well-known postictal automatism in complex partial seizures, considered very important for lateralization. We report a 24-year-old woman selected from 32 patients with video-EEG investigations of absence seizures. The patient, with normal examination and imaging findings, had typical absence seizures from the age of 5 years, which were controlled with either ethosuximide or valproate and worsened by carbamazepine. In two of her recorded typical absence seizures associated with generalized 3 Hz symmetric spike-wave discharges, she wiped her nose as an automatism in the ictal and post-ictal period. Our case showed that nose wiping could be associated with generalized seizures, in contrast to other recent reports.

The EEGs of elderly patients with a definite seizure disorder (161 patients; 302 EEGs) were compared to patients with "syncope" (122 patients; 133 EEGs), especially to determine if the latter patients were sufficiently similar to the seizure patients that the syncope could be viewed as a seizure phenomenon. The two groups were similar only by the predominance of females in both groups (61-62%) and otherwise were very different. The seizure group had a higher incidence of (1) etiology (83 vs. 39%), (2) epileptiform discharges (93 vs. 49%), with a different location, more often parasagittal, and different number often with active or very active foci, (3) frontal slow waves, (4) more severe slow wave abnormalities, (5) slower background frequencies, that were less well organized and developed and (6) abnormal records. The conclusion is that the syncope patients as a group are usually not simply seizure patients. Regardless of etiology, the patients with "syncope" (33% with cerebrovascular and 21% cardiac etiologies) showed nearly a 50% incidence of epileptiform discharges, demonstrating a complex interrelationship between cardiac and cerebral mechanisms, which are discussed. The conclusion is that epileptiform activity in elderly patients with syncope is likely to be mildly epileptogenic, and may require additional cardiovascular mechanisms to generate an attack of unconsciousness.