title: Response Rates to Anticonvulsant Trials in Patients with Triphasic-Wave EEG Patterns of Uncertain Significance.
abstract: BACKGROUND
  Generalized triphasic waves (TPWs) occur in both metabolic encephalopathies and non-convulsive status epilepticus (NCSE). Empiric trials of benzodiazepines (BZDs) or non-sedating AED (NSAEDs) are commonly used to differentiate the two, but the utility of such trials is debated. The goal of this study was to assess response rates of such trials and investigate whether metabolic profile differences affect the likelihood of a response.
  
  
  METHODS
  Three institutions within the Critical Care EEG Monitoring Research Consortium retrospectively identified patients with unexplained encephalopathy and TPWs who had undergone a trial of BZD and/or NSAEDs to differentiate between ictal and non-ictal patterns. We assessed responder rates and compared metabolic profiles of responders and non-responders. Response was defined as resolution of the EEG pattern and either unequivocal improvement in encephalopathy or appearance of previously absent normal EEG patterns, and further categorized as immediate (within <2 h of trial initiation) or delayed (>2 h from trial initiation).
  
  
  RESULTS
  We identified 64 patients with TPWs who had an empiric trial of BZD and/or NSAED. Most patients (71.9%) were admitted with metabolic derangements and/or infection. Positive clinical responses occurred in 10/53 (18.9%) treated with BZDs. Responses to NSAEDs occurred in 19/45 (42.2%), being immediate in 6.7%, delayed but definite in 20.0%, and delayed but equivocal in 15.6%. Overall, 22/64 (34.4%) showed a definite response to either BZDs or NSAEDs, and 7/64 (10.9%) showed a possible response. Metabolic differences of responders versus non-responders were statistically insignificant, except that the 48-h low value of albumin in the BZD responder group was lower than in the non-responder group.
  
  
  CONCLUSIONS
  Similar metabolic profiles in patients with encephalopathy and TPWs between responders and non-responders to anticonvulsants suggest that predicting responders a priori is difficult. The high responder rate suggests that empiric trials of anticonvulsants indeed provide useful clinical information. The more than twofold higher response rate to NSAEDs suggests that this strategy may be preferable to BZDs. Further prospective investigation is warranted.
authors.affiliation: Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, WACC 735, Boston, MA, 02114, USA.
authors.forename: Deirdre
authors.initials: D
authors.lastname: O'Rourke
authors.affiliation: Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, WACC 735, Boston, MA, 02114, USA.
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Chen
authors.affiliation: Hôpital Erasme - ULB, Cliniques universitaires de Bruxelles, Brussels, Belgium.|Neurology Department, Yale Comprehensive Epilepsy Center, New Haven, CT, USA.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Gaspard
authors.affiliation: Department of Neurology and Rehabilitation Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
authors.forename: Brandon
authors.initials: B
authors.lastname: Foreman
authors.affiliation: Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, WACC 735, Boston, MA, 02114, USA.
authors.forename: Lauren
authors.initials: L
authors.lastname: McClain
authors.affiliation: Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Karakis
authors.affiliation: Department of Neurology, Wayne State University, Detroit, MI, USA.
authors.forename: Advait
authors.initials: A
authors.lastname: Mahulikar
authors.affiliation: Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, WACC 735, Boston, MA, 02114, USA. mwestover@mgh.harvard.edu.
authors.forename: M Brandon
authors.initials: MB
authors.lastname: Westover
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000927:Anticonvulsants / Q000494:pharmacology*; D001569:Benzodiazepines / Q000494:pharmacology*; D001927:Brain Diseases / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D002986:Clinical Trials as Topic; D004569:Electroencephalography / Q000379:methods*; D006801:Humans; D055442:Metabolome; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D012189:Retrospective Studies; D013226:Status Epilepticus / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D055815:Young Adult
chemical_list: D000927:Anticonvulsants; D001569:Benzodiazepines
keywords: Encephalopathy; Generalized periodic discharges; Non-convulsive status epilepticus; Triphasic waves