Quantitative EEG alterations after isovolernic‐hemodilutional augmenhtion of cerebral perfhion in stroke patients

Abstract

Eleven patients with ischemic neurologic deficits in the middle cerebral arterial (MCA) territory and ipsilateral slowing on initial EEG underwent venesection and equal volume replacement with intravenous 5% human serum albumin. As the mean hematocrit was reduced by 19%, the mean cerebral blood flow (CBF) in the MCA territory of the affected and contralateral hemisphere determined by the 133Xenon inhalation technique increased 18 and 21%, respectively. Similarly, CBF in the contralateral occipital region increased 17%. The percentage total slow-wave EEG activity (fractional sum of theta and delta activity, 1.0 to 7.5 Hz) determined by fourier analysis was reduced significantly in the affected MCA territory and in the contralateral occipital region within 1 to 2 hours after isovolemic hemodilution. Using quantitative EEG analysis, rapid improvement in background EEG activity can be demonstrated following the diffuse elevation in CBF by hemodilution.

Baseline hemodynamic state and response to hemodilution in patients with acute cerebral ischemia.

“…Gottstein et al" first employed isovolemic hemodilution in acute stroke, and Wood et al demonstrated increased CBF and improved outcome as measured by quantitative EEG after isovolemic hemodilution in patients with stroke 16 and after EC-IC bypass." Hypervolemic hemodilution has been shown to increase both CO and CBF and reduce infarct size.…”

Quantitative EEG for the Detection of Brain Ischemia

“…events in acute ischemic stroke, coherence performed only modestly well in this study, perhaps because of the background changes associated with SAH in general. Similarly, although spectral edge frequencies correlate with ischemia in acute ischemic stroke [28] and carotid endarterectomy [29] and mean frequency changes correlate with improvements in CBF [20], frequency measures were not predictive of delayed cerebral ischemia in poorgrade SAH, potentially because of lower overall frequencies at baseline. Th ese parameters have not been adequately studied in better grade SAH, and may still hold some promise.…”

“…Additionally, EEG may assist in guiding treatment, to rapidly reverse the region at risk if it has not reached the infarction threshold. Examples include shunt placement in carotid endarterec tomy [3], tPA in acute ischemic stroke [18,19], and aug mentation of blood pressure or CBF after acute ischemic stroke [20].…”

The Utility of EEG, SSEP, and Other Neurophysiologic Tools to Guide Neurocritical Care

“…Good outcome may be seen in patients without significant slowing or change in background frequencies [44]. In addition, EEG may be used to demonstrate improvements in cerebral perfusion after induced hypertension or following volume challenges [46][47][48].…”