Intracortical EEG for the detection of vasospasm in patients with poor-grade subarachnoid hemorrhage.

BACKGROUND

To study the feasibility of utilizing intracortical electroencephalography (ICE) including quantitative EEG (qEEG) analysis for the detection of vasospasm in five consecutive poor-grade SAH patients.

METHODS

Intracortical electroencephalography (ICE) was obtained via a single miniature parenchymal 8-contact depth electrode placed at the bedside. Quantitative EEG parameters, calculated on surface EEG and ICE, included alpha/delta ratio (ADR), mean amplitude, suppression percent, and total power. Percent changes between averaged values over 4-6 h of baseline EEG and EEG prior to angiography were calculated. The entire continuous qEEG recording for each patient was then reviewed to determine optimal automated alarm criteria.

RESULTS

ICE ADR was the most accurate for predicting angiographic vasospasm (5/5). ICE ADR decreased between baseline and follow-up by 42% (from 0.56 ± 0.07 to 0.32 ± 0.03) for those with vasospasm (N = 3) compared to 17% (0.62 ± 0.06 to 0.51 ± 0.03) for those without (N = 2). A sustained decrease in the ICE ADR from baseline (>25% for ≥ 4 h) occurred in all three patients with angiographically confirmed vasospasm and not in the two without; this decline occurred 1-3 days prior to angiographic confirmation.

CONCLUSIONS

Intracortical EEG is promising for detecting ischemia from vasospasm in poor-grade SAH patients, may be superior to scalp EEG, and allow automated detection, particularly using the ADR. Larger studies are needed to better define the effectiveness of this approach.