Nonconvulsive status epilepticus with triphasic wave EEG pattern: a case report

Cover Page

Cite item

Full Text


Introduction. Triphasic waves in an electroencephalogram (EEG) in patients with decreased alertness traditionally is associated with hepatic encephalopathy. The development of digital technologies and the introduction of systems that allow long-term EEG monitoring of the neurocritical care patients has led to accumulation of significant experience in recording triphasic waves in various metabolic, toxic, and structural brain disorders, as well as in nonconvulsive status epilepticus.

Materials and methods. We present a case of diagnosis and successful treatment of a nonconvulsive status epilepticus, that developed in a female patient after CABG, and that presented electrographically as a triphasic wave pattern.

Results. Description of the patient’s EEG according to the classification of rhythmic and periodic patterns of the American Clinical Neurophysiology Society and the use of clinical and EEG criteria of nonconvulsive status epilepticus of the International League Against Epilepsy enabled us to correctly diagnose the cause of her decreased alertness and other neurological symptoms. Proper selection of the antiepileptic drugs along with monitoring of daily EEG recordings led to a recovery of consciousness in the patient and to normalization of the EEG pattern, which confirmed the clinical hypothesis of a nonconvulsive status epilepticus.

Conclusions. Utilization of the modern clinical and electrographic classifications enables the diagnosis of a nonconvulsive epileptic seizure and status epilepticus when the EEG pattern is ambiguous and traditionally associated with other conditions. EEG monitoring must be performed in patients with a sudden deterioration of consciousness that cannot be explained by brain imaging studies.

About the authors

Elena A. Baranova

Interregional Clinical Diagnostic Center

Author for correspondence.
Russian Federation, Kazan

Tatyana V. Danilova

Kazan State Medical University

Russian Federation, Kazan

Ilyas R. Khalitov

Interregional Clinical Diagnostic Center

Russian Federation, Kazan

Mikhail V. Sinkin

N.V. Sklifosovsky Research Institute for Emergency Medicine

Russian Federation, Moscow


  1. Bermeo-Ovalle A. Triphasic waves: swinging the pendulum back in this diagnostic dilemma. Epilepsy Curr 2017; 17: 40–42. doi: 10.5698/1535-7511-17.1.40. PMID: 28331470.
  2. Togo M., Kinoshita M. Hepatic encephalopathy revisited: beyond the triphasic waves. Clin Neurophysiol 2019; 130: 408–409. DOI:10.1016/j. clinph.2018.12.003. PMID: 30670335.
  3. Luders H., Noachtar S. Atlas and classification of electroencephalography. Philadelphia, 2000.
  4. Hirsch L.J., LaRoche S.M., Gaspard N. et al. American Clinical Neurophysiology Society’s Standardized Critical Care EEG Terminology: 2012 version. J Clin Neurophysiol 2013; 30: 1–27. doi: 10.22633/rpge. v20. n3.9743. PMID: 23377439.
  5. Sinkin M.V., Krylov V.V. Rhythmic and periodic EEG patterns. Classification and clinical significance. Zhurnal Nevrologii i Psikhiatrii im. S.S. Korsakova 2018; 118(10 Pt 2): 9–20. doi: 10.17116/jnevro20181181029. PMID: 30698539. (In Russ.)
  6. Kaplan P.W., Sutter R. Affair with triphasic waves — their striking presence, mysterious significance, and cryptic origins: what are they? J Clin Neurophysiol 2015; 32: 401–405. doi: 10.1097/WNP.0000000000000151. PMID: 26426768.
  7. Leitinger M., Beniczky S., Rohracher A. et al. Salzburg consensus criteria for non-convulsive status epilepticus — approach to clinical application. Epilepsy Behav 2015; 49: 158–163. doi: 10.1016/j.yebeh.2015.05.007. PMID: 26092326.
  8. Glauser T., Shinnar S., Gloss D. et al. Evidence-based guideline: treatment of convulsive status epilepticus in children and adults: report of the guideline committee of the American epilepsy society. Epilepsy Curr 2016; 16: 48–61. doi: 10.5698/1535-7597-16.1.48. PMID: 26900382.
  9. Leppik I.E. Status epilepticus in the elderly. Epilepsia 2018; 59(Suppl 2): 140–143. doi: 10.1111/epi.14497. PMID: 30159881.
  10. Trinka E., Leitinger M. Which EEG patterns in coma are nonconvulsive status epilepticus? Epilepsy Behav 2015; 49: 203–222. doi: 10.1016/j.yebeh. 2015.05.005. PMID: 26148985.
  11. Towne A.R., Waterhouse E.J., Boggs J.G. et al. Prevalence of nonconvulsive status epilepticus in comatose patients. Neurology 2000; 54: 340–345. doi: 10.1212/wnl.54.2.340. PMID: 10668693.
  12. Vespa P.M., O’Phelan K., Shah M. et al. Acute seizures after intracerebral hemorrhage: A factor in progressive midline shift and outcome. Neurology 2003; 60: 1441–1446. doi: 10.1212/01.WNL.0000063316.47591.b4. PMID: 12743228.
  13. Young G.B., Jordan K.G., Doig G.S. An assessment of nonconvulsive seizures in the intensive care unit using continuous EEG monitoring: An investigation of variables associated with mortality. Neurology 1996; 47: 83–89. doi: 10.1212/WNL.47.1.83. PMID: 8710130.
  14. Tu B., Young G.B., Kokoszka A. et al. Diagnostic accuracy between readers for identifying electrographic seizures in critically ill adults. Epilepsia Open 2017; 2: 67–75. doi: 10.1002/epi4.12034. PMID: 29750214.
  15. Beniczky S., Hirsch L.J., Kaplan P.W. et al. Unified EEG terminology and criteria for nonconvulsive status epilepticus. Epilepsia 2013; 54(Suppl 6): 28–29. doi: 10.1111/epi.12270. PMID: 24001066.
  16. Beniczky S., Aurlien H., Brogger J.C. et al. Standardized computer-based organized reporting of EEG: SCORE — Second version. Clin Neurophysiol 2017; 128: 2334–2346. doi: 10.1016/j.clinph.2017.07.418. PMID: 28838815.
  17. Foley J.M., Watson C.W., Adams R.D. Significance of the electroencephalographic changes in hepatic coma. Trans Am Neurol Assoc 1950; 51: 161–165. PMID: 14788100.
  18. Bickford R.G., Butt H.R. Hepatic coma: the electroencephalographic pattern. J Clin Invest 1955; 34: 790–799. doi: 10.1172/JCI103134. PMID: 14381508.
  19. Karnaze D.S., Bickford R.G. Triphasic waves: A reassessment of their significance. Electroencephalogr Clin Neurophysiol 1984; 57: 193–198. doi: 10.1016/0013-4694(84)90120. PMID: 6199180.
  20. Schomer D.L., Da Silva F.L. Niedermeyer's electroencephalography: basic principles, clinical applications, and related fields. Philadelphia 2012.
  21. Fisch B.J., Klass D.W. The diagnostic specificity of triphasic wave patterns. Electroencephalogr Clin Neurophysiol 1988; 70: 1–8. PMID: 2455625.
  22. Anand P., Kaplan P.W. Triphasic waves and encephalopathy in the setting of pregabalin toxicity. J Clin Neurophysiol 2018; 35: 515–517. doi: 10.1097/WNP.0000000000000511. PMID: 30222638.
  23. Sutter R., Kaplan P.W. Uncovering clinical and radiological associations of triphasic waves in acute encephalopathy: a case-control study. Eur J Neurol 2014; 21: 660–666. doi: 10.1111/ene.12372. PMID: 24506269.
  24. Shawcross D., Jalan R. The pathophysiologic basis of hepatic encephalopathy: central role for ammonia andinflammation. Cell Mol Life Sci 2005; 62: 2295–2304. doi: 10.1007/s00018-005-5089-0. PMID: 16158192.
  25. Ahboucha S., Butterworth R.F. Pathophysiology of hepatic encephalopathy: a new look at GABA from the molecular standpoint. Metab Brain Dis 2004; 19: 331–343. PMID: 15554425.
  26. Granner M.A., Lee S.I. Nonconvulsive status epilepticus EEG analysis in a large series. Epilepsia 1994; 35: 42–47. PMID: 8112256.
  27. Kaplan P.W. Nonconvulsive status epilepticus in the emergency room. Epilepsia 1996; 37: 643–650. PMID: 8681896.
  28. Boulanger J.M., Deacon C., Lécuyer D. et al. Triphasic waves versus nonconvulsivestatus epilepticus: EEG distinction. Can J Neurol Sci 2006; 33: 175–180. PMID: 16736726.
  29. Foreman B., Mahulikar A., Tadi P. et al. Generalized periodic discharges and “triphasic waves”: A blinded evaluation of inter-rater agreement and clinical significance. Clin Neurophysiol 2016; 127: 1073–1080. doi: 10.1016/j.clinph.2015.07.018. PMID: 26294138.
  30. Kaplan P.W., Schlattman D. Comparison of triphasic waves and epilepticdischarges in one patient with genetic epilepsy. J Clin Neurophysiol 2012; 29: 458–461. doi: 10.1097/WNP.0b013e31826bde70. PMID: 23027103.
  31. Alkhachroum A.M., Al-Abri H., Sachdeva A. et al. Generalized periodic discharges with and without triphasic morphology. J Clin Neurophysiol 2018; 35: 144–150. doi: 10.1097/WNP.0000000000000441. PMID: 29215453.
  32. Claassen J. How I treat patients with EEG patterns on the ictal-interictalcontinuum in the neuro ICU. Neurocrit Care 2009; 11: 437–444. doi: 10.1007/s12028-009-9295-8. PMID: 29215453.
  33. O’Rourke D., Chen P.M., Gaspard N. et al. Response rates to anticonvulsant trials in patients with triphasic-wave EEG patterns of uncertain significance. Neurocrit Care 2016; 24: 233–239. doi: 10.1007/s12028-015-0151-8. PMID: 26013921.
  34. Jirsch J., Hirsch L.J. Nonconvulsive seizures: developing a rational approach to the diagnosis and management in the critically ill population. J Clin Neurophysiol 2007; 118: 1660–1670. doi: 10.1016/j.clinph.2006.11.312. PMID: 17588812.
  35. Bauerschmidt A., Rubinos C., Claassen J. Approach to managing periodic discharges. J Clin Neurophysiol 2018; 35: 309–313. doi: 10.1097/WNP.0000000000000464. PMID: 29979289.
  36. Kaplan P.W, Birbeck G. Lithium-induced confusional states: nonconvulsive status epilepticus or triphasic encephalopathy? Epilepsia 2006; 47: 2071–2074. doi: 10.1111/j.1528-1167.2006.00849.x. PMID: 17201705.
  37. Kaplan P.W. EEG criteria for nonconvulsive status epilepticus. Epilepsia 2007; 48(Suppl 8): 39–41. PMID: 18329995.
  38. Fountain N.B., Waldman W.A. Effects of benzodiazepines on triphasic waves: implications for nonconvulsive status epilepticus. J Clin Neurophysiol 2001; 18: 345–352. PMID: 11673700.

Supplementary files

Supplementary Files

Copyright (c) 2020 Baranova E.A., Danilova T.V., Khalitov I.R., Sinkin M.V.

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.

СМИ зарегистрировано Федеральной службой по надзору в сфере связи, информационных технологий и массовых коммуникаций (Роскомнадзор).
Регистрационный номер и дата принятия решения о регистрации СМИ: серия ПИ № ФС 77-83204 от 12.05.2022.

This website uses cookies

You consent to our cookies if you continue to use our website.

About Cookies