Electroencephalography and clinical neurophysiology最新文献

We present clinical and EEG findings in 4 children with basilar migraine (BM) (three female and one male, age 11 to 13.5 years). All patients had an EEG during the acute attack and a follow-up EEG within 4 to 18 days. In two patients the EEG, done within 4 h of the onset of symptoms (initial stage), showed diffuse polymorphic subdelta-delta activity. In two other children the EEG, performed 16 h after the onset of symptoms, showed delta-theta activity predominant over the occipital regions. Resolution of these abnormalities during follow-up was observed in all patients. We wish to stress the danger of misinterpretation of the slow wave activity in the EEG of patients with BM attacks. Together with the clinical findings and their evolution, EEG results should not be interpreted as a sign of a structural brain-stem lesion, such as infarction or inflammation.

The aim of this study was to check the prognostic power of auditory brain-stem responses (ABRs) and somatosensory evoked potentials (SEPs) in coma following spontaneous cerebral hemorrhage. Seventy patients comatose following subarachnoidal or hypertensive hemorrhage were submitted to ABR and SEP recordings during the acute phase of clinical course. Twenty-one patients survived (30%), two remained vegetative (2.9%) and 47 died (68.1%). The Glasgow Coma Score (GCS) was significantly related to the outcome (P<0.001), but showed a low sensitivity, about 50% of patients with GCS=5–8 died or remained vegetative. ABRs and SEPs showed a much closer correlation with outcome (P<0.001): their combined use allowed there to be a sensitivity of 96%, a specificity of 90% and a predictive power of 96%; the relative risk of poor outcome in patients with at least one abnormal modality was equal to 223 times the one for patients with normal evoked potentials. Moreover, in surviving patients a significant relationship appeared to exist between abnormalities of SEPs during the acute phase and the severity of disability. Our results confirm the prognostic effectiveness of short latency evoked potentials in cerebral hemorrhage: they are far superior to clinical data, being able to yield a marked decrease of falsely optimistic predictions.

Objectives: To prove or disprove the assumption that in neuropathy patients with abundant spontaneous activity, peak-ratio interference pattern analysis may lead to false negative results.Methods: Spontaneous activity >100 μV, automatically analysed by turn/amplitude analysis and expressed as (turns/second)/2 ((T/S)/2), and interference patterns, analysed by the peak-ratio technique, were recorded, one after the other, from the right anterior tibial muscle of 21 patients with neuropathy, aged 36–87 years.Results: The mean number of spontaneous discharges ((T/S)/2) was 12.3 (range 5.5–26) and its mean amplitude 261 μV (range 146–478 μV). Despite this abundant spontaneous activity, peak-ratio analysis was neurogenic in 81% of the patients. All peak-ratio parameters were independent on the amount and amplitude of spontaneous discharges.Conclusions: Spontaneous discharges >100 μV could be adequately assessed by means of the turn/amplitude analysis and did not influence peak-ratio analysis in neuropathies.

Objective: To review the EEG features of ring 20 syndrome in two patients to disclose the characteristic pattern of this syndrome. The features of our cases and 24 patients reported in the literature will be discussed.

Subjects and methods: Report of two patients and review of literature.

Results: The two patients had intractable epilepsy since childhood. Their clinical seizures were mostly complex partial seizures. Often the patients seizures were of prolonged duration. Ictal EEG revealed characteristic slow waves, and sharp waves. The slow waves were (1) usually synchronous high-voltage slow waves with or without a spike component predominantly in the frontal and frontopolar areas, (2) sometimes showed a change in frequency every several seconds, (3) continued for a long period, and (4) easily spread diffusely. The sharp waves were 5–6 Hz irregular and diffuse discontinuous sharp waves, and sometimes appeared predominantly in the centroparietal area. The clinical seizure pattern and EEG findings were similar in the 24 published cases.

Conclusions: These EEG findings may be a characteristic feature of ring 20 syndrome and thus may be useful as a diagnostic clue.

Objectives: Slow potentials appearing during simple repetitive acral limb movement were investigated. Twenty-six patients suffering from drug resistant partial epilepsies and explored with implanted intracerebral electrodes were examined using two protocols.Methods: In 18 patients, readiness potential (RP), in 13 patients contingent negative variation (CNV), and in 7 patients both protocols, were tested. The recordings from leads with evident pathological EEG activity were excluded from evaluation. The results concerning the slow potentials preceding the movements in RP and CNV protocols have already been published. Results: The movement-accompanying slow potentials (MASP) were polyphasic or monophasic, started before or during the movement. In the primary motor cortex they followed the pre-movement potentials depending on the protocol: in the RP paradigm they were present only contralateral to the movement, but were bilateral in the CNV protocol. In other areas they either followed the potentials preceding the movement, in some cases with opposite polarity, or they occurred alone. MASP was recorded in motor and supplementary motor, premotor and prefrontal, midtemporal, somatosensory, superior parietal and cingular cortices. The cingular cortex was heavily involved in the self-paced movements but rarely in the cued movements.Conclusion: The major involvement of the cingular gyrus contrasted with the absence of slow potentials in temporal limbic structures. MASP is evidently a heterogenic phenomenon. Its genesis could be involved in a spread of information through the relevant structures.

This study was designed to relate visual perception of motion to cortical activity, by evaluation of the association of quantified electroencephalogram (qEEG) parameters with a video film projection. The EEG was recorded from 14 sites according to the International 10–20 system and a common average reference was used. Forty right-handed volunteers (mean age=24 years) were examined. The video film consisted of 20 s sequences showing still shots and moving shots with human movements or object movements. The EEG was then subjected to spectral analysis; the spectral powers for the theta, alpha and beta bands were calculated for 14 s epochs and compared with sequences of the video film. All analyses were based on logarithmically transformed absolute spectral power values. The power values of each frequency band were analysed in a 3-way repeated measure ANOVA (Hemisphere×Electrode×Sequence). The results were represented by EEG cartography. Significant decreases in the alpha 1, beta 1 and beta 2 power values of EEG in centro-parietal regions of both hemispheres were shown during perception of human motion sequences. This suggests participation of the sensorimotor cortex during visual observation of human motion.

Neurophysiological techniques for the evaluation of pain in humans have made important advances in the last decade. A number of features of neuroanatomy and physiology of nociception qualifies pain as a multidimensional phenomenon which is rather unique among the sensory systems and which poses a number of technical and procedural requirements for its appropriate diagnostic assessment. Various stimulation techniques to induce defined pain in humans and used in combination with the methodology of evoked electrical brain potentials and magnetic fields are presented. Most recent knowledge gathered from scalp topography and dipole source analysis of pain-relevant evoked potentials and fields is discussed. Particular emphasis is put upon laser-evoked potentials and their application for diagnosis, pathophysiological description and monitoring of patients with neurological disorders and abnormal pain states. Future perspectives in this growing field of research are discussed briefly.

To study hemispheric lateralization of cortical potentials associated with motoric and non-motoric function, cortical activity was recorded accompanying either finger extension or saccadic eye movements in a contingent negative variation (CNV) paradigm. Subjects viewed computer-generated pacing stimuli, presented in the left visual hemi-field, and were instructed to either initiate or inhibit a motor response following an imperative signal. Motoric lateralization was assessed by means of the lateralized readiness potential (LRP). In addition, a measure complementary to the LRP was introduced to investigate non-motoric lateralization (NML). Contralateral inter-hemispheric lateralization was evident in the LRP preceding finger movement, but was absent prior to eye movements. However, pre-saccadic cortical response profiles did exhibit a right hemispheric, non-motoric lateralization (NML) during stimulus presentation. Comparable non-motoric lateralization was found for finger extension. Results of the present study suggest that non-motoric lateralization may be a contributing factor to the frequently reported inter-hemispheric asymmetry preceding self-initiated saccadic eye movements. Results of the present study also suggest that the latter may be related to a covert shift of visuospatial attention toward the saccadic target. Associated shifts of attention are suppressed in a CNV paradigm, where attentional focus is primarily on the CNV stimulus during the pre-saccade period.