摘要:

ABSTRACT.In neurosurgery today, the EEG is still an important and useful diagnostic tool, particularly in the assessment of the cerebral state and its dynamic changes in the comatose patient. The totality of generalized EEG changes, like amplitude, frequency, or the development of specific EEG patterns, already permits a good estimation of the depth of coma, whereas focal changes are hardly expressive. Particular attention should be paid to alpha activities in the coma, which need to be well differentiated, since they may constitute completely different phenomena of various causes and prognoses. The spontaneous EEG frequently provides prognostic indications, but long-term monitoring with frequency analysis should also be performed to diagnose the existence of autorhythm.The changes of the EEG in comatose patients in response to stimulation by exogenous acoustic, nociceptive, and visual stimuli, and also by medication, may yield additional information. The administration of centrally active drugs such as barbiturates or benzodiazepines is able to reveal the capacity of the brain for fundamental physiological EEG reaction, thus providing a test for the integrity of cerebral structures despite loss of consciousness. This type of functional EEG therefore seems to deliver quite exact information on the extent of irreversible damage and on the prognosis.

ISSN:0002-9238    

DOI:10.1080/00029238.1991.11080359

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

ABSTRACT.The recent development of large array multichannel biomagnetometers allows the recording of spatiotemporally coherent data sets by simultaneous sampling of magnetic brain activity over a wide extracranial region. The use of such an instrument greatly enhances the speed and the quality of neuromagnetic measurements. To test the reproducibility and validity of neuromagnetic source localization (NMSL), auditory evoked field (AEF) data were repeatedly collected from a single test subject in thirty independent replications. Highly reproducible AEF waveforms, essentially superimposible for the major components M50, M100, and M200, were obtained. When analyzed for source locations using a single equivalent current dipole model, these analyses demonstrated consistent localizations for the sources of M50, M100, and M200 waves with standard deviations of a few millimeters. Clear spatial separation of the sources of the M100 and M200 components was demonstrated. Comparison with MRI showed that equivalent current dipole sources were localized to the region of Heschl's gyrus and the transverse portion of the superior temporal gyrus. Present limitations on NMSL arise from restrictions of the source and body models now in use.

ISSN:0002-9238    

DOI:10.1080/00029238.1991.11080360

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

ABSTRACT.An automated software-driven long-term EEG monitoring system operating through a readily available personal computer (PC) is described. Heart rate acceleration has been used to indicate seizure activity. The recorded seizures are stored on a library tape. This system has simplified recordings, reduced staff requirement, and minimized searching of video cassette recording tapes to detect the electrical and video recording of seizures.

ISSN:0002-9238    

DOI:10.1080/00029238.1991.11080361

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

ABSTRACT.Electrical signals generated in any biological system can travel to the surface by volume conduction. Near-field potentials are generated close to the recording electrode; far- field potentials are generated at a distance from the recording electrode. Biological electrical signals are often dipoles with a negative and a positive end. EEG and evoked potential studies may record one or both ends of the dipole, as either near-field or far-field potentials. The morphology and apparent polarity of recorded waveforms are determined in part by the orientation of the dipole, the direction of spread, and the derivation used for recording.

ISSN:0002-9238    

DOI:10.1080/00029238.1991.11080362

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0002-9238    

DOI:10.1080/00029238.1991.11080363

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0002-9238    

DOI:10.1080/00029238.1991.11080364

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0002-9238    

DOI:10.1080/00029238.1991.11080365

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0002-9238    

DOI:10.1080/00029238.1991.11080366

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0002-9238    

DOI:10.1080/00029238.1991.11080367

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0002-9238    

DOI:10.1080/00029238.1991.11080368

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor