Correlation of Continuous Electroencephalograms With Cerebral Blood Flow Measurements During Carotid Endarterectomy

Abstract

During an 11-month period, 81 endarterectomies under a carefully controlled level of general anesthesia were monitored with continuous electroencephalograms (EEG) and intermittent regional cerebral blood flow (CBF) measurements. There was a high correlation between the CBF (milliliter per 100 gm per minute) during carotid occlusion and alterations in the EEG: no EEG change was seen with the flow above 30 ml/100 gm brain per minute, major changes were not seen with a flow between 18 and 30 ml, and changes invariably occurred with a flow below 17 ml. The degree of EEG change reflected the severity of flow reduction but was always reversible with the placement of a shunt. The EEG at the termination of the surgery corresponded with the patient's neurological state in that all EEG tracings were normal or unchanged as compared to the preoperative tracing and no neurological worsening occurred in any patients studied. The EEG is a valuable monitoring technique that indicates when a shunt is required and informs the surgeon of the state of cerebral function not only during occlusion but also throughout the entire operative procedure.

The Impact of a Regular Blood Donation on the Hematology and EEG of Healthy Young Male Blood Donors

“…EEG is a well established technique that has been used in the field of clinical medicine such as carotid endarterectomy for several decades (Sharbrough et al 1973;Cursi et al 2005). Perturbations of the on-going EEG have been demonstrated from eyes-closed to eyesopen conditions in the EEG default mode network (EEG MDN).…”

Continuous EEG Monitoring for Early Detection of Delayed Cerebral Ischemia in Subarachnoid Hemorrhage: A Pilot Study

“…When neuronal function is compromised due to insufficient cortical perfusion, various EEG changes occur, such as depression of fast activity or slowing of rhythms [9]. This deterioration of neuronal function is potentially reversible, providing a window of opportunity for therapeutic interventions [10][11][12]. The EEG might be suitable to detect DCI at an early stage and monitor effects of therapeutic interventions.…”

Quantitative EEG Correlates of Low Cerebral Perfusion in Severe Stroke

“…The relationship between EEG changes and cerebral blood flow has been demonstrated previously, and there is extensive literature on the use of EEG for intra-operative monitoring, for example, during carotid endarterectomy [20][21][22][23][24][25][26][27][28]. Previous studies have clearly documented a relationship between cerebral blood flow and EEG changes [21,25,29]. Changes in EEG such as loss of fast beta frequencies occurred when CBF dropped below 35 ml/ 100 mg/kg; a further reduction was shown to provoke slowing of the background activity to theta rhythms, and a drop in CBF to below 18 ml/100 mg/min has been associated with slowing to delta activity.…”

“…Suppression of all the frequencies was associated with neuronal cell death and a CBF below 10 ml/100 mg/min (for review see [30]). While some studies report good reliability of EEG monitoring [21,23,27,28], others failed to detect consistently cerebral ischemia [20,22,26,31]. The same holds true for quantitative and higher-order measures of EEG analysis [32][33][34][35].…”