title: Continuous EEG Monitoring for Early Detection of Delayed Cerebral Ischemia in Subarachnoid Hemorrhage: A Pilot Study.
abstract: BACKGROUND
  Early identification of delayed cerebral ischemia (DCI) in patients with aneurysmal subarachnoid hemorrhage (aSAH) is a major challenge. The aim of this study was to investigate whether quantitative EEG (qEEG) features can detect DCI prior to clinical or radiographic findings.
  
  
  METHODS
  A prospective cohort study was performed in aSAH patients in whom continuous EEG (cEEG) was recorded. We studied 12 qEEG features. We compared the time point at which qEEG changed with the time point that clinical deterioration occurred or new ischemia was noted on CT scan.
  
  
  RESULTS
  Twenty aSAH patients were included of whom 11 developed DCI. The alpha/delta ratio (ADR) was the most promising feature that showed a significant difference in change over time in the DCI group (median -62% with IQR -87 to -39%) compared to the control group (median +27% with IQR -32 to +104%, p = 0.013). Based on the ROC curve, a threshold was chosen for a combined measure of ADR and alpha variability (AUC: 91.7, 95% CI 74.2-100). The median time that elapsed between change of qEEG and clinical DCI diagnosis was seven hours (IQR -11-25). Delay between qEEG and CT scan changes was 44 h (median, IQR 14-117).
  
  
  CONCLUSIONS
  In this study, ADR and alpha variability could detect DCI development before ischemic changes on CT scan was apparent and before clinical deterioration was noted. Implementation of cEEG in aSAH patients can probably improve early detection of DCI.
authors.affiliation: Department of Intensive Care Medicine, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands. marjolijnrots@gmail.com.|Clinical Neurophysiology Group, MIRA - Institute for Biomedical Technology and Technical Medicine, University of Twente, Hallenweg 15, 7522 NB, Enschede, The Netherlands. marjolijnrots@gmail.com.
authors.forename: M L
authors.initials: ML
authors.lastname: Rots
authors.affiliation: Clinical Neurophysiology Group, MIRA - Institute for Biomedical Technology and Technical Medicine, University of Twente, Hallenweg 15, 7522 NB, Enschede, The Netherlands.|Department of Neurology and Clinical Neurophysiology, Medisch Spectrum Twente, Haaksbergerstraat 55, 7513 ER, Enschede, The Netherlands.
authors.forename: M J A M
authors.initials: MJ
authors.lastname: van Putten
authors.affiliation: Department of Intensive Care Medicine, Radboud University Nijmegen Medical Center, Geert Grooteplein-Zuid 10, 6525 GA, Nijmegen, The Netherlands.
authors.forename: C W E
authors.initials: CW
authors.lastname: Hoedemaekers
authors.affiliation: Department of Intensive Care Medicine, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Horn
mesh_terms: D000368:Aged; D002545:Brain Ischemia / Q000175:diagnosis* / Q000209:etiology; D042241:Early Diagnosis; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011446:Prospective Studies; D013345:Subarachnoid Hemorrhage / Q000150:complications / Q000175:diagnosis*
keywords: Aneurysmal subarachnoid hemorrhage; Continuous EEG monitoring; Delayed cerebral ischemia; Early detection; Quantitative EEG