Relative Alpha Variability Changes Precede Alpha-Delta Ratio Changes in Cerebral Ischemia.

The utility of quantitative EEG in early detection of cerebral ischemia is still underappreciated in clinical practice. We present a case of aneurysmal subarachnoid hemorrhage complicated by vasospasm as detected by the cerebral angiogram. The patient was being monitored on electroencephalogram. It showed early signs of cerebral ischemia represented by decline in the Alpha-Delta-Ratio (ADR) and the Relative-Alpha-Variability (RAV). Surprisingly, the RAV changes preceded the ADR changes. This is a significant finding that can also apply to early reocclusion or reperfusion injuries after mechanical thrombectomy.