title: Association of Periodic and Rhythmic Electroencephalographic Patterns With Seizures in Critically Ill Patients.
abstract: OBJECTIVE
  Periodic and rhythmic electroencephalographic patterns have been associated with risk of seizures in critically ill patients. However, specific features that confer higher seizure risk remain unclear.
  
  
  OBJECTIVE
  To analyze the association of distinct characteristics of periodic and rhythmic patterns with seizures.
  
  
  METHODS
  We reviewed electroencephalographic recordings from 4772 critically ill adults in 3 academic medical centers from February 2013 to September 2015 and performed a multivariate analysis to determine features associated with seizures.
  
  
  METHODS
  Continuous electroencephalography.
  
  
  METHODS
  Association of periodic and rhythmic patterns and specific characteristics, such as pattern frequency (hertz), Plus modifier, prevalence, and stimulation-induced patterns, and the risk for seizures.
  
  
  RESULTS
  Of the 4772 patients included in our study, 2868 were men and 1904 were women. Lateralized periodic discharges (LPDs) had the highest association with seizures regardless of frequency and the association was greater when the Plus modifier was present (58%; odds ratio [OR], 2.00, P < .001). Generalized periodic discharges (GPDs) and lateralized rhythmic delta activity (LRDA) were associated with seizures in a frequency-dependent manner (1.5-2 Hz: GPDs, 24%,OR, 2.31, P = .02; LRDA, 24%, OR, 1.79, P = .05; ≥ 2 Hz: GPDs, 32%, OR, 3.30, P < .001; LRDA, 40%, OR, 3.98, P < .001) as was the association with Plus (GPDs, 28%, OR, 3.57, P < .001; LRDA, 40%, P < .001). There was no difference in seizure incidence in patients with generalized rhythmic delta activity compared with no periodic or rhythmic pattern (13%, OR, 1.18, P = .26). Higher prevalence of LPDs and GPDs also conferred increased seizure risk (37% frequent vs 45% abundant/continuous, OR, 1.64, P = .03 for difference; 8% rare/occasional vs 15% frequent, OR, 2.71, P = .03, vs 23% abundant/continuous, OR, 1.95, P = .04). Patterns associated with stimulation did not show an additional risk for seizures from the underlying pattern risk (P > .10).
  
  
  CONCLUSIONS
  In this study, LPDs, LRDA, and GPDs were associated with seizures while generalized rhythmic delta activity was not. Lateralized periodic discharges were associated with seizures at all frequencies with and without Plus modifier, but LRDA and GPDs were associated with seizures when the frequency was 1.5 Hz or faster or when associated with a Plus modifier. Increased pattern prevalence was associated with increased risk for seizures in LPDs and GPDs. Stimulus-induced patterns were not associated with such risk. These findings highlight the importance of detailed electroencephalographic interpretation using standardized nomenclature for seizure risk stratification and clinical decision making.
authors.affiliation: Emory University School of Medicine, Atlanta, Georgia.
authors.forename: Andres
authors.initials: A
authors.lastname: Rodriguez Ruiz
authors.affiliation: Georgia Institute of Technology, Atlanta.
authors.forename: Jan
authors.initials: J
authors.lastname: Vlachy
authors.affiliation: Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Jong Woo
authors.initials: JW
authors.lastname: Lee
authors.affiliation: Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Gilmore
authors.affiliation: Georgia Institute of Technology, Atlanta.
authors.forename: Turgay
authors.initials: T
authors.lastname: Ayer
authors.affiliation: Emory University School of Medicine, Atlanta, Georgia.
authors.forename: Hiba Arif
authors.initials: HA
authors.lastname: Haider
authors.affiliation: Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Gaspard
authors.affiliation: Emory University School of Medicine, Atlanta, Georgia.
authors.forename: J Andrew
authors.initials: JA
authors.lastname: Ehrenberg
authors.affiliation: Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Tolchin
authors.affiliation: Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Tadeu A
authors.initials: TA
authors.lastname: Fantaneanu
authors.affiliation: Thomas Jefferson University, Philadelphia, Pennsylvania.
authors.forename: Andres
authors.initials: A
authors.lastname: Fernandez
authors.affiliation: Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Hirsch
authors.affiliation: Emory University School of Medicine, Atlanta, Georgia7Mission Health, Asheville, North Carolina.
authors.forename: Suzette
authors.initials: S
authors.lastname: LaRoche
mesh_terms: D058256:Brain Waves / Q000502:physiology*; D015331:Cohort Studies; D016638:Critical Illness; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D010507:Periodicity; D012640:Seizures / Q000453:epidemiology* / Q000503:physiopathology*