Can the Processed EEG Be Utilized as a Cerebral Ischemia Monitor during the Temporary Clip Application in Anterior Circulation Aneurysm Surgery?

Patients undergoing cerebral aneurysm clipping are at risk for cerebral ischemia. Ischemic tolerance varies among individuals. Hence, multimodal intraoperative neuromonitoring (IONM) is essential. IONM is not available in many centers. This case report highlights the utilization of processed electroencephalography (EEG) as a cerebral ischemia monitor during temporary clip application. Our patient underwent clipping of a ruptured anterior-communicating artery aneurysm. After the temporary clip applications on the right and left, A1 arterial segments led to a transient drop of somatosensory evoked potentials (SSEPs). At the same time, the frontal four-channel processed EEG showed a burst suppression (BS) pattern. Blood pressure augmentation and the removal of temporary clips helped restore the SSEP back to baseline and the disappearance of the BS pattern in processed EEG. During the steady state of anesthesia, the sudden appearance of the BS pattern in processed EEG can be attributed to clip-induced cerebral ischemia after ruling out other potential causes for BS.