title: Generalized periodic discharges and 'triphasic waves': A blinded evaluation of inter-rater agreement and clinical significance.
abstract: OBJECTIVE
  Generalized periodic discharges (GPDs) are associated with nonconvulsive seizures. Triphasic waves (TWs), a subtype of GPDs, have been described in relation to metabolic encephalopathy and not felt to be associated with seizures. We sought to establish the consistency of use of this descriptive term and its association with seizures.
  
  
  METHODS
  11 experts in continuous EEG monitoring scored 20 cEEG samples containing GPDs using Standardized Critical Care EEG Terminology. In the absence of patient information, the inter-rater agreement (IRA) for EEG descriptors including TWs was assessed along with raters' clinical EEG interpretation and compared with actual patient information.
  
  
  RESULTS
  The IRA for 'generalized' and 'periodic' was near-perfect (kappa=0.81), but fair for 'triphasic' (kappa=0.33). Patients with TWs were as likely to develop seizures as those without (25% vs 26%, N.S.) and surprisingly, patients with TWs were less likely to have toxic-metabolic encephalopathy than those without TWs (55% vs 79%, p<0.01).
  
  
  CONCLUSIONS
  While IRA for the terms "generalized" and "periodic" is high, it is only fair for TWs. EEG interpreted as TWs presents similar risk for seizures as GPDs without triphasic appearance. GPDs are commonly associated with metabolic encephalopathy, but 'triphasic' appearance is not predictive.
  
  
  CONCLUSIONS
  Conventional association of 'triphasic waves' with specific clinical conditions may lead to inaccurate EEG interpretation.
authors: Columbia University Medical Center, Division of Critical Care Neurology, 177 Fort Washington Ave, Milstein 8 Center Room, New York, NY 10032, USA. Electronic address: brandon.foreman@uc.edu.
authors: Brandon
authors: B
authors: Foreman
authors: Columbia University Medical Center, Division of Critical Care Neurology, 177 Fort Washington Ave, Milstein 8 Center Room, New York, NY 10032, USA.
authors: Advait
authors: A
authors: Mahulikar
authors: Columbia University Medical Center, Division of Critical Care Neurology, 177 Fort Washington Ave, Milstein 8 Center Room, New York, NY 10032, USA.
authors: Prasanna
authors: P
authors: Tadi
authors: Columbia University Medical Center, Division of Critical Care Neurology, 177 Fort Washington Ave, Milstein 8 Center Room, New York, NY 10032, USA.
authors: Jan
authors: J
authors: Claassen
authors: University of Alabama at Birmingham, Department of Neurology, 1719 6th Avenue South, CIRC 312, Birmingham, AL 35294, USA.
authors: Jerzy
authors: J
authors: Szaflarski
authors: Medical University of South Carolina, Department of Neurology, 96 Jonathan Lucas St. CSB 301, Charleston, SC 29425, USA.
authors: Jonathan J
authors: JJ
authors: Halford
authors: Clemson University, School of Computing, 100 McAdams Hall, Clemson, SC 29634, USA.
authors: Brian C
authors: BC
authors: Dean
authors: Johns Hopkins Bayview Medical Center, Department of Neurology, 301 Mason Lord Drive, Ste 2100, Baltimore, MD 21224, USA.
authors: Peter W
authors: PW
authors: Kaplan
authors: Yale University, Department of Neurology, 15 York Street, LCI 300, New Haven, CT 06520, USA.
authors: Lawrence J
authors: LJ
authors: Hirsch
authors: Emory University School of Medicine, Department of Neurology, 1365 Clifton Rd, Atlanta, GA 30322, USA.
authors: Suzette
authors: S
authors: LaRoche
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D058256:Brain Waves / Q000502:physiology; D015331:Cohort Studies; D004569:Electroencephalography / Q000379:methods / Q000592:standards*; D006801:Humans; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D012640:Seizures / Q000175:diagnosis* / Q000503:physiopathology*; D016037:Single-Blind Method
keywords: Critical care; EEG monitoring; Inter-rater agreement; Periodic discharges; Seizures; Triphasic waves