title: Decreased functional connectivity and disturbed directionality of information flow in the electroencephalography of intensive care unit patients with delirium after cardiac surgery.
abstract: BACKGROUND
  In this article, the authors explore functional connectivity and network topology in electroencephalography recordings of patients with delirium after cardiac surgery, aiming to improve the understanding of the pathophysiology and phenomenology of delirium. The authors hypothesize that disturbances in attention and consciousness in delirium may be related to alterations in functional neural interactions.
  
  
  METHODS
  Electroencephalography recordings were obtained in postcardiac surgery patients with delirium (N = 25) and without delirium (N = 24). The authors analyzed unbiased functional connectivity of electroencephalography time series using the phase lag index, directed phase lag index, and functional brain network topology using graph analysis.
  
  
  RESULTS
  The mean phase lag index was lower in the α band (8 to 13 Hz) in patients with delirium (median, 0.120; interquartile range, 0.113 to 0.138) than in patients without delirium (median, 0.140; interquartile range, 0.129 to 0.168; P < 0.01). Network topology in delirium patients was characterized by lower normalized weighted shortest path lengths in the α band (t = -2.65; P = 0.01). δ Band-directed phase lag index was lower in anterior regions and higher in central regions in delirium patients than in nondelirium patients (F = 4.53; P = 0.04, and F = 7.65; P < 0.01, respectively).
  
  
  CONCLUSIONS
  Loss of α band functional connectivity, decreased path length, and increased δ band connectivity directed to frontal regions characterize the electroencephalography during delirium after cardiac surgery. These findings may explain why information processing is disturbed in delirium.
authors.affiliation: From the Department of Intensive Care Medicine, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands (E.v.D., A.W.v.d.K., T.N., A.J.C.S.); Alzheimer Center and Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands (E.v.D.); Department of Clinical Neurophysiology and MEG Center, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands (E.v.D., C.J.S.); MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands (T.N.); Department of Geriatrics, University Medical Center Utrecht, Utrecht, The Netherlands (H.L.K.); Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands (F.A.M.K.); and Department of Cardio-Thoracic Surgery, University Medical Center Utrecht, Utrecht, The Netherlands (M.P.B.).
authors.forename: Edwin
authors.initials: E
authors.lastname: van Dellen
authors.forename: Arendina W
authors.initials: AW
authors.lastname: van der Kooi
authors.forename: Tianne
authors.initials: T
authors.lastname: Numan
authors.forename: Huiberdina L
authors.initials: HL
authors.lastname: Koek
authors.forename: Francina A M
authors.initials: FA
authors.lastname: Klijn
authors.forename: Marc P
authors.initials: MP
authors.lastname: Buijsrogge
authors.forename: Cornelis J
authors.initials: CJ
authors.lastname: Stam
authors.forename: Arjen J C
authors.initials: AJ
authors.lastname: Slooter
mesh_terms: D018806:APACHE; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D006348:Cardiac Surgical Procedures / Q000009:adverse effects* / Q000523:psychology*; D003221:Confusion / Q000523:psychology; D003422:Critical Care / Q000458:organization & administration*; D003430:Cross-Sectional Studies; D003625:Data Collection; D003627:Data Interpretation, Statistical; D003693:Delirium / Q000209:etiology / Q000503:physiopathology* / Q000523:psychology*; D004569:Electroencephalography / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007362:Intensive Care Units / Q000458:organization & administration*; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000187:drug effects*; D011183:Postoperative Complications / Q000503:physiopathology* / Q000523:psychology*; D011595:Psychomotor Agitation / Q000523:psychology