title: Bedside quantitative electroencephalography improves assessment of consciousness in comatose subarachnoid hemorrhage patients.
abstract: Accurate behavioral assessments of consciousness carry tremendous significance in guiding management, but are extremely challenging in acutely brain-injured patients. We evaluated whether electroencephalography (EEG) and multimodality monitoring parameters may facilitate assessment of consciousness in patients with subarachnoid hemorrhage.
  
  
  
  A retrospective analysis was performed of 83 consecutively treated adults with subarachnoid hemorrhage. All patients were initially comatose and had invasive brain monitoring placed. Behavioral assessments were performed during daily interruption of sedation and categorized into 3 groups based on their best examination as (1) comatose, (2) arousable (eye opening or attending toward a stimulus), and (3) aware (command following). EEG features included spectral power and complexity measures. Comparisons were made using bootstrapping methods and partial least squares regression.
  
  
  
  We identified 389 artifact-free EEG clips following behavioral assessments. Increasing central gamma, posterior alpha, and diffuse theta-delta oscillations differentiated patients who were arousable from those in coma. Command following was characterized by a further increase in central gamma and posterior alpha, as well as an increase in alpha permutation entropy. These EEG features together with basic neurological examinations (eg, pupillary light reflex) contributed heavily to a linear model predicting behavioral state, whereas brain physiology measures (eg, brain oxygenation), structural injury, and clinical course added less.
  
  
  
  EEG measures of behavioral states provide distinctive signatures that complement behavioral assessments of patients with subarachnoid hemorrhage shortly after the injury. Our data support the hypothesis that impaired connectivity of cortex with both central thalamus and basal forebrain underlies decreasing levels of consciousness. Ann Neurol 2016;80:541-553.
authors.affiliation: Department of Neurology, Columbia University, New York, NY. jc1439@columbia.edu.
authors.forename: Jan
authors.initials: J
authors.lastname: Claassen
authors.affiliation: Department of Neurology, Columbia University, New York, NY.
authors.forename: Angela
authors.initials: A
authors.lastname: Velazquez
authors.affiliation: Department of Neurology, Columbia University, New York, NY.
authors.forename: Emma
authors.initials: E
authors.lastname: Meyers
authors.affiliation: Department of Neurology, Columbia University, New York, NY.
authors.forename: Jens
authors.initials: J
authors.lastname: Witsch
authors.affiliation: Department of Neurology, Columbia University, New York, NY.
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Falo
authors.affiliation: Department of Neurology, Columbia University, New York, NY.
authors.forename: Soojin
authors.initials: S
authors.lastname: Park
authors.affiliation: Department of Neurology, Columbia University, New York, NY.
authors.forename: Sachin
authors.initials: S
authors.lastname: Agarwal
authors.affiliation: Department of Neurology, Columbia University, New York, NY.
authors.forename: J
authors.initials: J
authors.lastname: Michael Schmidt
authors.affiliation: Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, NY.
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Schiff
authors.affiliation: Institute for Brain and Spinal Cord Research Center, National Institute of Health and Medical Research, Paris, France.
authors.forename: Jacobo D
authors.initials: JD
authors.lastname: Sitt
authors.affiliation: Institute for Brain and Spinal Cord Research Center, National Institute of Health and Medical Research, Paris, France.
authors.forename: Lionel
authors.initials: L
authors.lastname: Naccache
authors.affiliation: Department of Neurosurgery, Columbia University, New York, NY.
authors.forename: E
authors.initials: E
authors.lastname: Sander Connolly
authors.affiliation: Department of Neurology, Columbia University, New York, NY.
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Frey
mesh_terms: D000368:Aged; D003128:Coma / Q000175:diagnosis* / Q000209:etiology; D003244:Consciousness Disorders / Q000175:diagnosis* / Q000209:etiology; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination / Q000379:methods*; D064926:Neurophysiological Monitoring; D000067716:Point-of-Care Testing; D012189:Retrospective Studies; D013345:Subarachnoid Hemorrhage / Q000150:complications*