Quantitative electroencephalography for delayed cerebral ischemia diagnosis

Quantitative electroencephalography for delayed cerebral ischemia diagnosis

The association between alpha-delta ratio (ADR) on quantitative electroencephalography (EEG) and DCI has been reported in several previous studies, but their results are conflicting 1).

Focal reduction in alpha power may represent a valid, observer-independent, non-invasive and continuous marker for vasospasm/DCI in SAH patients 2).

A prolonged alpha-theta/delta (AT/D) ratio decrease seems to be a reliable biomarker of DCI 3).

In a study, Mueller et al. aimed to compare and analyze the ability of qEEG and transcranial color-coded duplex ultrasonography (TCD/TCCS) to early identify patients who will develop later manifest cerebral infarction.

They analyzed cohorts of two previous qEEG studies. Continuous six-channel-EEG with artifact rejection and a detrending procedure was applied. Alpha power decline of ≥ 40% for ≥ 5 hours compared to a 6-hour-baseline was defined as a significant EEG event. Median reduction and duration of alpha power decrease in each channel were determined. Vasospasm was diagnosed by TCD/TCCS, identifying the maximum frequency and days of vasospasm in each territory.

34 patients were included (17 male, mean age 56 ± 11 years, Hunt and Hess grade: I-V, cerebral infarction: 9). Maximum frequencies in TCD/TCCS and alpha power reduction in qEEG were correlated (r = 0.43; p = 0.015). Patients with and without infarction significantly differed in qEEG parameters (maximum alpha power decrease: 78% vs 64%, p = 0.019; summed hours of alpha power decline: 236 hours vs 39 hours, p = 0.006) but showed no significant differences in TCD/TCCS parameters.

There was a moderate correlation between TCD/TCCS frequencies and qEEG alpha power reduction but only qEEG differentiated between patients with and without cerebral infarction.

Significance: qEEG represents a non-invasive, continuous tool to identify patients at risk of cerebral infarction 4).


Yu Z, Wen D, Zheng J, Guo R, Li H, You C, Ma L. The predictive accuracy of alpha-delta ratio on quantitative electroencephalography for delayed cerebral ischemia in patients with aneurysmal subarachnoid hemorrhage: a meta-analysis. World Neurosurg. 2019 Feb 27. pii: S1878-8750(19)30493-0. doi: 10.1016/j.wneu.2019.02.082. [Epub ahead of print] PubMed PMID: 30825635.

Gollwitzer S, Groemer T, Rampp S, Hagge M, Olmes D, Huttner HB, Schwab S, Madžar D, Hopfengaertner R, Hamer HM. Early prediction of delayed cerebral ischemia in subarachnoid hemorrhage based on quantitative EEG: A prospective study in adults. Clin Neurophysiol. 2015 Aug;126(8):1514-23. doi: 10.1016/j.clinph.2014.10.215. Epub 2014 Nov 14. PMID: 25500193.

Balança B, Dailler F, Boulogne S, Ritzenthaler T, Gobert F, Rheims S, Andre-Obadia N. Diagnostic accuracy of quantitative EEG to detect delayed cerebral ischemia after subarachnoid hemorrhage: A preliminary study. Clin Neurophysiol. 2018 Sep;129(9):1926-1936. doi: 10.1016/j.clinph.2018.06.013. Epub 2018 Jul 5. PMID: 30007892.

Mueller TM, Gollwitzer S, Hopfengärtner R, Rampp S, Lang JD, Stritzelberger J, Madžar D, Reindl C, Sprügel MI, Dogan Onugoren M, Muehlen I, Kuramatsu JB, Schwab S, Huttner HB, Hamer HM. Alpha power decrease in quantitative EEG detects development of cerebral infarction after subarachnoid hemorrhage early. Clin Neurophysiol. 2021 Mar 26:S1388-2457(21)00465-X. doi: 10.1016/j.clinph.2021.03.005. Epub ahead of print. PMID: 33867261.

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