Neurocritical Care

, Volume 22, Issue 3, pp 450–461 | Cite as

Continuous EEG Monitoring in Aneurysmal Subarachnoid Hemorrhage: A Systematic Review

  • Daniel Kondziella
  • Christian K. Friberg
  • Ian Wellwood
  • Clemens Reiffurth
  • Martin Fabricius
  • Jens P. Dreier
Review Article



Continuous EEG (cEEG) may allow monitoring of patients with aneurysmal subarachnoid hemorrhage (SAH) for delayed cerebral ischemia (DCI) and seizures, including non-convulsive seizures (NCSz), and non-convulsive status epilepticus (NCSE). We aimed to evaluate: (a) the diagnostic accuracy of cEEG as a confirmatory test, (b) the prognostic value of EEG patterns suggestive of seizures and DCI, and (c) the effectiveness of intensified neuromonitoring using cEEG in terms of improved clinical outcome following SAH.


A systematic review was performed with eligible studies selected from multiple indexing databases through June 2014. The methodological quality of these studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2.


Eighteen studies were identified, including cEEG data from 481 patients with aneurysmal SAH. NCSz were diagnosed in 7–18 % of patients; NCSE in 3–13 %. NCSE was associated with increased age (mean age 68 years) and mortality (82–100 %) compared to the entire patient population (53.9 years; mortality 13 %; p values <0.05). DCI was diagnosed in 20–46 % of patients. Quantitative EEG patterns suggestive of DCI included decreased alpha/delta ratio, relative alpha variability, and total power. All studies were subject to a high risk of bias concerning patient selection and cEEG methodology.


cEEG monitoring following SAH detects an increased number of subclinical seizures and may predict DCI many hours in advance. NCSE is associated with high mortality and morbidity, whereas for DCI identified by cEEG this association is less clear. Prospective randomized controlled multicenter trials are needed to evaluate the benefits (or risks) of intensified treatment of seizures and DCI following SAH.


Aneurysm Delayed cerebral ischemia Epilepsy Status epilepticus Quantitative EEG Seizures Spreading depolarizations Spreading ischemia Stroke Subarachnoid bleeding Vasospasm 



This study was supported by the following Grants DFG DR 323/5-1, BMBF 01 EO 0801, BMBF 01GQ1001C B2, FP7 no 602150 CENTER-TBI.

Ethics statement

This paper is a systematic review of previously published literature, which is why the local ethics committee (Copenhagen University) waived the need for formal approval.

Supplementary material

12028_2014_68_MOESM1_ESM.docx (49 kb)
Supplementary material 1 (DOCX 49 kb)


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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Daniel Kondziella
    • 1
    • 3
    • 4
  • Christian K. Friberg
    • 2
  • Ian Wellwood
    • 4
  • Clemens Reiffurth
    • 4
    • 6
  • Martin Fabricius
    • 2
  • Jens P. Dreier
    • 4
    • 5
    • 6
  1. 1.Department of NeurologyRigshospitalet, Copenhagen University HospitalCopenhagenDenmark
  2. 2.Department of Clinical NeurophysiologyRigshospitalet, Copenhagen University HospitalCopenhagenDenmark
  3. 3.Institute of NeuroscienceNorwegian University of Science and TechnologyTrondheimNorway
  4. 4.Center for Stroke Research BerlinCharité - Universitätsmedizin BerlinBerlinGermany
  5. 5.Department of NeurologyCharité - Universitätsmedizin BerlinBerlinGermany
  6. 6.Department of Experimental NeurologyCharité - Universitätsmedizin BerlinBerlinGermany

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