EEG Asymmetry During Aortic Arch Surgeries Associated With Selective Preferential Cerebral Hypothermia

Abstract

Intraoperative EEG monitoring is increasingly used during aortic arch procedures for early detection of acute neurologic dysfunction. In those procedures involving cardiopulmonary bypass, increased neuroprotection may be gained by using hypothermic circulatory arrest and selective cerebral perfusion. Several techniques for cerebral perfusion exist; yet no studies have noted distinct EEG patterns associated with different techniques. In this study, we reviewed EEG records of six aortic arch procedures that used cannulation of the innominate artery to provide selective antegrade cerebral perfusion. In each case, a transient hemispheric asymmetry was noted within 2 minutes of the start of head cooling, consisting of enhanced suppression over the right compared with the left hemisphere, which was confirmed by power analysis. The EEG returned to baseline during passive-head rewarming in five cases, whereas a brief left-sided partial seizure occurred during rewarming in one case. These findings suggest that antegrade cerebral perfusion using cannulation of the innominate artery results in enhanced cooling of the right hemisphere as detected by intraoperative EEG monitoring. Characterization of this finding is necessary to prevent misinterpretation of ischemia by EEG.

Perioperative electroencephalography in cardiac surgery with hypothermic circulatory arrest: a narrative review

“…When detected, this resulted in a change in cannulation strategy; the depth of hypothermia prior to circulatory arrest or the CPB/cerebral perfusion pump flow/blood pressure augmentation; and postoperative imaging and catheter-based interventions. A retrospective study of aortic arch procedures identified asymmetries in EEG activity between left and right hemispheres following innominate artery cannulation, reflecting uneven active cooling of the brain [ 34 ].…”

“…postoperatively only (2, 5%, n=283) [6,32], or a combination of pre-, intra-and/or postoperatively (19, 48%, n=759) [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51]. Thirty nine (98%, n=3,276) studies reported a combination of clinical and EEG outcomes of interest, the other (n=11) focussed solely on EEG analysis technique [29].…”

“…The most common EEG outcome measure reported was an assessment of EEG continuity during cooling and rewarming (18, 45%), which was used to predict postoperative outcome, assess anaesthetic depth, and guide HCA strategy [13,[15][16][17][18]20,22,24,26,27,29,[34][35][36]39,43,47,48]. Of these, three (17%) studies report longer durations of non-continuous EEG following HCA associated with postoperative neurological dysfunction [13,24,41], and in three there was a trend that was either not significant or not associated with outcome [18,27,48]…”

Intraoperative Electroencephalogram-Guided Deep Hypothermia Plus Antegrade and/or Retrograde Cerebral Perfusion During Aortic Arch Surgery

“…A method of physiological monitoring, intraoperative EEG, was introduced by Ganzel et al in 1997 8 and reported by Tobochnik et al in 2014. 9 Stecker et al 10 reported that the process of cooling to electrocerebral silence produced a uniform degree of cerebral protection, independent of the actual nasopharyngeal temperature. We believe intraoperative EEG to be the best method for monitoring brain activity physiologically, and we routinely use it in elective cases and in urgent cases if available.…”

“…It has been shown that body temperature measurement may not be a reliable indicator of brain temperature, and although a number of modalities, such as near‐infrared spectroscopy and transcranial cerebral oximetry, have been introduced to monitor the brain during arch surgery, no single technique has proven to be a perfect monitoring tool. A method of physiological monitoring, intraoperative EEG, was introduced by Ganzel et al in 1997 and reported by Tobochnik et al in 2014 . Stecker et al reported that the process of cooling to electrocerebral silence produced a uniform degree of cerebral protection, independent of the actual nasopharyngeal temperature.…”