Quantitative EEG After Subarachnoid Hemorrhage Predicts Long-Term Functional Outcome

Area of Science:

• Neuroscience
• Neurology
• Critical Care Medicine

Background:

• Delayed cerebral ischemia (DCI) is a significant complication following subarachnoid hemorrhage (SAH).
• Previous research indicated that alpha power reduction in quantitative EEG (qEEG) can predict DCI.
• The prognostic value of qEEG alpha power for long-term outcomes in SAH patients requires further investigation.

Purpose of the Study:

• To evaluate the prognostic significance of alpha power in qEEG for predicting long-term functional outcomes in patients with SAH.
• To determine if qEEG alpha power can serve as a reliable biomarker for patient recovery after SAH.

Main Methods:

• A prospective cohort study included adult patients with nontraumatic SAH, with EEG initiated within 72 hours of symptom onset.
• Continuous six-channel EEG monitoring was performed, followed by automated artifact rejection and power spectral analysis.
• A critical EEG event was defined as an alpha power decline of ≥40% for ≥5 hours; six-month outcomes were assessed using the modified Rankin Scale (mRS).

Main Results:

• Of 22 patients, 16 with critical EEG events had a high rate of poor outcomes (69%, mRS 2-5).
• All 6 patients without critical EEG events achieved excellent outcomes (mRS 0-1), showing a significant difference (P=0.0062).
• EEG events preceded vasospasm detection and had a weaker association with outcome compared to EEG findings; no significant association was found between EEG events, imaging lesions, or outcome.

Conclusions:

• Stable alpha power in qEEG is associated with successful therapy and predicts favorable functional outcomes post-SAH.
• A critical reduction in alpha power is a strong indicator of increased risk for poor functional outcomes.
• qEEG alpha power analysis offers valuable prognostic information for SAH patients.