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Biomedical subjects

B J Fisch

Publications and source records attributed to B J Fisch.

7 recordsLinked to original sources
PubMed1991

Quantitative EEG monitoring for patients with subarachnoid hemorrhage.

We evaluated the sensitivity of continuous quantitative EEG in 11 patients with subarachnoid hemorrhage (SAH). We correlated compressed spectral array (CSA) and trend analysis (TA) of total power (1-30 Hz), frequency centroid (1-30 Hz), alpha ratio and percent delta power with clinical and radiological findings. For all ischemic events (n = 11), the most sensitive TA parameter was a change in total power (91%), followed by changes in alpha ratio (64%), frequency centroid (55%), and percent delta (45%). Comparable CSA features were changes in power (44%) and slowing (39%). Total power and frequency varied independently. In 4 cases, EEG findings on TA appeared before clinical changes. Continuous quantitative EEG may be useful for monitoring and predicting ischemia following SAH. TA of individual EEG parameters is more sensitive than CSA, and total power is the most sensitive.

Adult↗
PubMed1991

The weighted average reference montage.

In this article we describe the implementation of a linearly weighted average reference montage. This montage differs from the commonly used source derivation montage in that the reference includes all the scalp electrodes of the 10-20 system; and it differs from all other montages implemented thus far in that the weighting of the reference electrodes is based on directly measured interelectrode distances. Using EEG and computer generated signals we have been able to demonstrate that the weighted average reference montage combines topographic selectivity and accuracy in the display of both focal and regional background changes. In comparison to the source derivation montage, ectopic peaks and troughs of localized potential fields are less prominent and interhemispheric symmetry is better preserved. In comparison to the common average reference montage the frequent prominent ectopic displacement of high amplitude (e.g., vertex waves) or widespread potentials (e.g., alpha background activity) is suppressed. We believe that the spatial filtering characteristics of the weighted average reference montage, which are intermediate between those of the common average reference montage and the source derivation and Laplacian montages, will make it a useful alternative for topographic analysis. Our results also indicate that actual scalp measurements should be used to calculate reference electrode weighting factors because such measurements yield values that are substantially different from those derived from other methods of estimation presented thus far. A weighted average montage derived from pooled scalp measurements can be easily implemented using the weighting factors provided herein.

Adult↗
PubMed1989

The EEG response to diffuse and patterned photic stimulation during acute untreated alcohol withdrawal.

We studied the responses to diffuse and patterned stroboscopic light stimulation prospectively in 49 individuals during acute alcohol withdrawal prior to pharmacologic treatment. Photomyogenic responses (PMR) occurred in only two (4%) of those tested, and photoparoxysmal responses (PPR) never occurred. These findings suggest that PMR occur far less often during alcohol withdrawal than previously thought and that PPR may not be a direct manifestation of alcohol withdrawal.

Adult↗
PubMed1988

A topographic background symmetry display for comparison with routine EEG.

We describe a new approach for assessing EEG background symmetry by topographic display of spectral band amplitude. Asymmetry is expressed as a percentage in much the same way that routine EEG symmetry comparisons are made. Spectral graphs of each channel are simultaneously displayed to facilitate interpretation. This method enhances the use of topographic mapping as an adjunct to conventional EEG interpretation.

Brain Mapping↗
PubMed1988

The diagnostic specificity of triphasic wave patterns.

A blind analysis of 56 EEGs with triphasic wave patterns was performed to determine the diagnostic specificity of individual electrographic features. EEG and clinical variables analyzed included longitudinal topography, phase lags, symmetry, background activity, reactivity, longitudinal bipolar phase reversal sites, responses to photic stimulation and mental status at the time of recording. The only statistically significant finding for any of the diagnostic groups tested was the presence of severe background slowing in cases of hepatic encephalopathy (P less than 0.001). We found no evidence to suggest that other features may contribute to a more highly characteristic pattern for hepatic encephalopathy. None of the features studied reliably distinguished hepatic encephalopathy from other forms of metabolic encephalopathy.

Adult↗
PubMed1985

Evaluation of focal cerebral lesions. Role of electroencephalography in the era of computed tomography.

We have reviewed the principal electroencephalographic findings in focal cerebral lesions and indicated practical applications for EEG in the era of CT. CT has restricted the use of EEG for detecting and localizing brain lesions, but it has also allowed EEG to focus appropriately on physiologic rather than anatomic issues. Clinically important focal electroencephalographic abnormalities may occur in the absence of CT lesions, and clinicians must understand the implications of such dissociations.

Adult↗