Electroencephalographic sleep elements and outcome in acute encephalopathic patients: a 4-year cohort study.
OBJECTIVE
Acute encephalopathy in hospitalized patients is common and associated with high mortality. Preservation of physiological sleep has been associated with favorable outcomes in acute brain injury. It is hypothesized that electroencephalographic presence of sleep elements is associated with good outcome in encephalopathic adults.


METHODS
This observational study was performed at an academic tertiary medical care center. Clinical data, electroencephalogram (EEG) characteristics and outcome of critically ill patients with acute encephalopathy were assessed. EEGs were interpreted regarding the presence of sleep elements (K-complexes, vertex sharp-waves and sleep spindles). Associations between sleep elements and outcome (graded by the Glasgow Outcome Scale, GOS) were analyzed.


RESULTS
One hundred and forty-two consecutive patients with a median age of 64.5 years (range 18-98) and mean Glasgow Coma Scale 10.4 (± 3.8) were included. Leading etiologies were infections (47.2%), intracranial hemorrhages (14.1%) and ischaemic strokes (10.6%). All EEGs demonstrated encephalopathy patterns and 38% had ≥ 1 sleep element (27.5% K-complexes, 31.7% vertex sharp-waves and 33.8% sleep spindles). Patients without sleep elements were older (P = 0.010) and septic shock was more common (P = 0.014). Amongst sleep elements, K-complexes were significantly associated with good outcome, even after adjusting for possible confounders (odds ratio for GOS 5 = 2.79, 95% confidence interval 1.16-6.69) and without significant effect modification across subgroups.


CONCLUSIONS
Whilst EEG sleep elements were detected more frequently in patients with favorable outcome, only K-complexes were significantly and independently associated with good outcome in intensive care unit patients with acute encephalopathy, findings that need to be confirmed in larger prospective studies.
Division of Neurosciences Critical Care, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neurology, Johns Hopkins Bayview Medical Center, Baltimore, MD, USA; Clinic of Intensive Care Medicine, University Hospital Basel, Basel, Switzerland; Division of Clinical Neurophysiology, Department of Neurology, University Hospital Basel, Basel, Switzerland.
R
R
Sutter
B
B
Barnes
A
A
Leyva
P W
PW
Kaplan
R G
RG
Geocadin
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001927:Brain Diseases / Q000503:physiopathology*; D015331:Cohort Studies; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D023261:Glasgow Outcome Scale; D006801:Humans; D008297:Male; D008875:Middle Aged; D012890:Sleep / Q000502:physiology*; D016896:Treatment Outcome; D055815:Young Adult
electroencephalography; encephalopathy; mortality; neurocritical care; outcome; sleep elements