1. R Sutter PW Kaplan European Journal of Neurology 2014
Uncovering clinical and radiological associations of triphasic waves in acute encephalopathy: a case-control study
R Sutter PW Kaplan
European Journal of Neurology
2014

2. Distinct, repetitive elements 3 phases
TRIPHASIC WAVES
Distinct, repetitive elements
3 phases
Negative wave
Surface positive high amplitude sharp transient >70 µV
Decrease on stimulation
Central > frontal localization ?
Lack of unilaterality
More V shaped (gentler rate of decline on the second phase)
More background activity
No response to benzodiazepines

3. Background
8-20% rate of non convulsive status epilepticus in critically ill encephalopathic patients
Many reported EEG patterns of unclear significance in critically ill encephalopathic patients
Triphasic waves have been reported in case reports and series in patients with hepatic encephalopathy and other toxic/metabolic encephalopathies
Reader variance in classifying triphasics
Debate on their etiology, epileptic classification and prognostic significance
Reported % mortality in patients with triphasic waves
This paper published in 2014 “with an aim to confirm and quantify assumed clinical and neuroradiological associations with triphasic waves and to elucidate whether poor outcome is independently related to triphasic waves”
Generalized spike waves are more acute, narrowed angled, briefer frontopolar empahasis
Triphasics are longer duration, frontocentral, stimulus altered, blunter

4. Data collected over 8 years (2004-2012) Setting: ICU patients
METHODS:
Data collected over 8 years ( )
Setting: ICU patients
Diagnosis: Encephalopathy
Definition: altered consciousness with change in cognition or with an acute perceptual disturbance that was not better accounted for by pre-existing dementia
Cases: with Triphasic waves (TWs) Controls: without TWs
Chart review
EEGs: at least 2 separate EEG with at least 20minutes of data
EEG readers: blinded to clinical diagnosis
CT or MRI: read by 2 neuroradiologist, 1 neurologist blinded to clinical diagnosis
Outcomes:
Primary: death
Encephalopathy: developed hours to days
Seizures: convulsions <5minutes, convulsive SE >5minutes, or repetitive convulsions without return to baseline
Non-consulsive seizures and status
EEG readers: if divergent – consensus reached after joint review
Imaging: WMC (mild, mod, severe), atrophy (cortical, subcortical) , infarction, ICH, brain tumros

5. Mortality: Cases 19% Controls 11% OR 2 CI 0.85-4.67% Older p 0.06
Inter-rater agreement:
Kappa: measures inter-rater agreement for qualitative categorical items, (mutually exclusive categories) between TWO raters
Takes into account the possibility of agreement occurring by chance
Complete agreement k = 1 , no agreement other than that expected by change k ~ 0
EEG k = 0.81
Neuro imaging k = 0.76

6. ALL significant an ODDs ratio that those disease were RF to be associated with TWs
The conditions that had significant ODDS ratios where further evaluated with MV regression, in which they still showed significant ODDs ratio
PREDICTOR
Multi variable evaluated if other predictors are effecting the univariable odds ratio
(verse indirect effect from another predictor)
Conditional univariable logistic regression – used to calculate ODDs ratio
IF significant in univariable logistic regression – included in conditional multivariable regression
Stepwise logistic regression using step forward and step backward selection
And Akaike information
To assess collinerarity multiple linear regression
Mean variable inflation factor was 1.11 – ruling out high collinearity of the included variables MEANS -----

7. Cumulative Effect of Independent Predictors
1 independent predictor – OR TW 2.4
2 or mote OR 9.2

8. Strengths
Provided more data to support an association between toxic metabolic encephalopathies (infection, liver disease) and presence of triphasic waves on EEG
Accounted for cofounding factors of background EEG activity and GCS

9. Limitations No causation with case control study
Not all patients had continuous cEEG
Non differential mis classification: under estimate hypothesized relationship
Differential mis classification over estimate

11.
O'Rourke D, Chen PM, Gaspard N, Foreman B, McClain L, Karakis I, Mahulikar A, Westover MB . Response Rates to Anticonvulsant Trials in Patients with Triphasic-Wave EEG Patterns of Uncertain Significance. Neurocrit Care 2016;24:233–239.
Bermeo-Ovalle A .Triphasic Waves: Swinging the Pendulum Back in this Diagnostic Dilemma Epilepsy Curr Jan-Feb;17(1): doi: /
Kaplan PW, Sutter R. Affair With Triphasic Waves-Their Striking Presence, Mysterious Significance, and Cryptic Origins: What are They?. J Clin Neurophysiol Oct