title: Functional connectivity and network analysis during hypoactive delirium and recovery from anesthesia.
abstract: To gain insight in the underlying mechanism of reduced levels of consciousness due to hypoactive delirium versus recovery from anesthesia, we studied functional connectivity and network topology using electroencephalography (EEG).
  
  
  
  EEG recordings were performed in age and sex-matched patients with hypoactive delirium (n=18), patients recovering from anesthesia (n=20), and non-delirious control patients (n=20), all after cardiac surgery. Functional and directed connectivity were studied with phase lag index and directed phase transfer entropy. Network topology was characterized using the minimum spanning tree (MST). A random forest classifier was calculated based on all measures to obtain discriminative ability between the three groups.
  
  
  
  Non-delirious control subjects showed a back-to-front information flow, which was lost during hypoactive delirium (p=0.01) and recovery from anesthesia (p<0.01). The recovery from anesthesia group had more integrated network in the delta band compared to non-delirious controls. In contrast, hypoactive delirium showed a less integrated network in the alpha band. High accuracy for discrimination between hypoactive delirious patients and controls (86%) and recovery from anesthesia and controls (95%) were found. Accuracy for discrimination between hypoactive delirium and recovery from anesthesia was 73%.
  
  
  
  Loss of functional and directed connectivity were observed in both hypoactive delirium and recovery from anesthesia, which might be related to the reduced level of consciousness in both states. These states could be distinguished in topology, which was a less integrated network during hypoactive delirium.
  
  
  
  Functional and directed connectivity are similarly disturbed during a reduced level of consciousness due to hypoactive delirium and sedatives, however topology was differently affected.
authors.affiliation: Department of Intensive Care Medicine, Brain Center Rudolf Magnus, University Medical Center Utrecht, Heidelberglaan 100, Utrecht, The Netherlands. Electronic address: t.numan-2@umcutrecht.nl.
authors.forename: Tianne
authors.initials: T
authors.lastname: Numan
authors.affiliation: Department of Intensive Care Medicine, Brain Center Rudolf Magnus, University Medical Center Utrecht, Heidelberglaan 100, Utrecht, The Netherlands.
authors.forename: Arjen J C
authors.initials: AJC
authors.lastname: Slooter
authors.affiliation: Department of Intensive Care Medicine, Brain Center Rudolf Magnus, University Medical Center Utrecht, Heidelberglaan 100, Utrecht, The Netherlands.
authors.forename: Arendina W
authors.initials: AW
authors.lastname: van der Kooi
authors.affiliation: Department of Intensive Care Medicine, Brain Center Rudolf Magnus, University Medical Center Utrecht, Heidelberglaan 100, Utrecht, The Netherlands.
authors.forename: Annemieke M L
authors.initials: AML
authors.lastname: Hoekman
authors.affiliation: Department of Cardiothoracic Surgery, University Medical Center Utrecht, Heidelberglaan 100, The Netherlands.
authors.forename: Willem J L
authors.initials: WJL
authors.lastname: Suyker
authors.affiliation: Department of Clinical Neurophysiology and MEG Center, Neuroscience Campus Amsterdam, VU University Medical Center, De Boelelaan 1085, Amsterdam, The Netherlands.
authors.forename: Cornelis J
authors.initials: CJ
authors.lastname: Stam
authors.affiliation: Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht, Heidelberglaan 100, Utrecht, The Netherlands.
authors.forename: Edwin
authors.initials: E
authors.lastname: van Dellen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000513:Alpha Rhythm; D000762:Anesthesia Recovery Period; D016022:Case-Control Studies; D003243:Consciousness; D003700:Delta Rhythm; D000071257:Emergence Delirium / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male
keywords: Delirium; Electroencephalography; Encephalopathy; Functional connectivity; Reduced level of consciousness; Sedation