Neurocritical Care

, Volume 22, Issue 2, pp 202–211 | Cite as

Non-convulsive Status Epilepticus and Non-convulsive Seizures in Neurological ICU Patients

  • Ikuko Laccheo
  • Hasan Sonmezturk
  • Amar B. Bhatt
  • Luke Tomycz
  • Yaping Shi
  • Marianna Ringel
  • Gina DiCarlo
  • DeAngelo Harris
  • John Barwise
  • Bassel Abou-Khalil
  • Kevin F. Haas
Original Article



Non-convulsive seizures (NCS) or non-convulsive status epilepticus (NCSE) has been reported in 8–20 % of critically ill patient populations, and delayed diagnosis and treatment of NCSE may lead to increased mortality. This study seeks to better understand the risk factors, characteristics, and outcome of NCS/NCSE in the neurological ICU.


This is a prospective observational study, recruiting consecutive patients admitted to the adult neurological ICU with altered mental status. Patients with anoxic brain injury were excluded from the study. Data were collected and analyzed for prevalence of NCSE/NCS, EEG patterns, associated risk factors, treatment response, and final outcome.


NCSE/NCS was detected in 21 % of 170 subjects. Clinical seizures preceded EEG diagnosis of NCSE/NCS in 25 % of cases. Significant risk factors for NCSE/NCS were a past medical history of intracranial tumor, epilepsy, or meningitis/encephalitis, or MRI evidence of encephalomalacia. Subtle clinical findings such as twitching of oral or ocular muscles and eye deviations were found on exam in 50 % of the NCSE/NCS group. Mortality was increased in NCSE cases as 31 % of NCSE/NCS patients died compared to 14 % in non-NCSE/NCS group.


Specific clinical features along with history and imaging findings may be used to identify patients at high risk of NCSE/NCS in the neurological ICU.


Neurological ICU Critical care Altered mental status Non-convulsive seizures Non-convulsive status epilepticus EEG 


Conflict of interest

Ikuko Laccheo, Hasan Sonmezturk, Amar Bhatt, Luke Tomycz, Yaping Shi, Marianna Ringel, Gina DiCarlo, DeAngelo Harris, John Barwise, and Bassel Abou-Khalil declare that they have no conflicts of interest.


  1. 1.
    Towne AR, Waterhouse EJ, Boggs JG, et al. Prevalence of nonconvulsive status epilepticus in comatose patients. Neurology. 2000;54(2):340–5.CrossRefPubMedGoogle Scholar
  2. 2.
    Benbadis SR, Tatum WO. Prevalence of non-convulsive status epilepticus in comatose patients. Neurology. 2000;55(9):1421–3.CrossRefPubMedGoogle Scholar
  3. 3.
    Claassen J, Mayer SA, Kowalski RG, Emerson RG, Hirsch LJ. Detection of electrographic seizures with continuous electroencephalography in critically ill patients. Neurology. 2004;62(10):1743–8.CrossRefPubMedGoogle Scholar
  4. 4.
    Oddo M, Carrera E, Claassen J, Mayer SA, Hirsch LJ. Continuous electroencephalography in the medical intensive care unit. Crit Care Med. 2009;37(6):2051–6.CrossRefPubMedGoogle Scholar
  5. 5.
    Young GB, Jordan KG, Doigt GS. An assessment of nonconvulsive seizures in the intensive care unit, using continuous EEG monitoring: an investigation of variables associated with mortality. Neurology. 1996;47(1):83–9.CrossRefPubMedGoogle Scholar
  6. 6.
    Pandian JD, Cascino GD, So EL, Manno E, Fulgham JR. Digital video-electroencephalographic monitoring in the neurological-neurosurgical intensive care unit: clinical features and outcome. Arch Neurol. 2004;61(7):1090–4.PubMedGoogle Scholar
  7. 7.
    Privitera M, Hoffman M, Moore JL, Jester D. EEG detection of nontonic-clonic status epilepeticus in patients with altered consciousness. Epilepsy Res. 1994;18(2):155–66.CrossRefPubMedGoogle Scholar
  8. 8.
    Vespa PM, Nuwer MR, Nenov V, et al. Increased incidence and impact of non- convulsive and convulsive seizures after traumatic brain injury as detected by continuous electroencephalographic monitoring. J Neurosurg. 1999;91(5):750–60.CrossRefPubMedCentralPubMedGoogle Scholar
  9. 9.
    Young GB, Kreeft JH, McLachalan RS, Demelo J. EEG and clinical association with mortality in comatose patients in a general intensive care unit. J Clin Neurophysiol. 1999;16(4):354–60.CrossRefPubMedGoogle Scholar
  10. 10.
    Jordan KG. Continuous EEG and evoked potential monitoring in the neuroscience intensive care unit. J Clin Neurophysiol. 1993;10(4):445–75.CrossRefPubMedGoogle Scholar
  11. 11.
    Firosh Khan S, Ashalatha R, Thomas SV, Sarma PS. Emergent EEG is helpful in neurology critical care practice. Clin Neurophysiol. 2005;116(10):2454–9.CrossRefPubMedGoogle Scholar
  12. 12.
    DeLorenzo RJ, Waterhouse EJ, Towne AR, et al. Persistent nonconvulsive status epilepticus after the control of convulsive status epilepticus. Epilepsia. 1998;39(8):833–40.CrossRefPubMedGoogle Scholar
  13. 13.
    Walker MC. Status epilepticus on the intensive care unit. J Neurol. 2003;250(4):401–6.CrossRefPubMedGoogle Scholar
  14. 14.
    Towne AR, Pellock JM, Ko D, DeLorenzo RJ. Determinants of mortality in status epilepticus. Epilepsia. 1994;35(1):27–34.CrossRefPubMedGoogle Scholar
  15. 15.
    DeLorenzo RJ, Garnett LK, Towne AR, et al. Comparison of status epilepticus with prolonged seizure episodes lasting from 10 to 29 minutes. Epilepsia. 1999;40(2):164–9.CrossRefPubMedGoogle Scholar
  16. 16.
    Waterhouse EJ, Garnett LK, Towne AR, et al. Prospective population-based study of intermittent and continuous convulsive status epilepeticus in Richmond, Virginia. Epilepsia. 1999;40(6):752–8.CrossRefPubMedGoogle Scholar
  17. 17.
    Drislane FW, Lopez MR, Blum AS, Schomer DL. Detection and treatment of refractory status epilepticus in the intensive care unit. J Clin Neurophysiol. 2008;25(4):181–6.CrossRefPubMedGoogle Scholar
  18. 18.
    Cooper AD, Britton JW, Rabinstein AA. Functional and cognitive outcome in prolonged refractory status epilepticus. Arch Neurol. 2009;66(12):1505–9.PubMedGoogle Scholar
  19. 19.
    Jordan KG, Schneider AL. Emergency “stat” EEG in the era of nonconvulsive status epilepticus. Am J Electroneurodiagnostic Technol. 2009;49(1):94–104.PubMedGoogle Scholar
  20. 20.
    Husain AM, Horn GJ, Jacobson MP. Non-convulsive status epilepticus: usefulness of clinical features in selecting patients for urgent EEG. J Neurol Neurosurg Psychiatry. 2003;74(2):189–91.CrossRefPubMedCentralPubMedGoogle Scholar
  21. 21.
    Kaplan PW. EEG criteria for nonconvulsive status. Epilepsia. 2007;48(suppl.8):39–41.CrossRefPubMedGoogle Scholar
  22. 22.
    Kramer AH, Jette N, Pillay N, Federico P, Zygun DA. Epilpeptiform activities in neurocritical care patients. Can J Neurol Sci. 2012;39(3):328–37.CrossRefPubMedGoogle Scholar
  23. 23.
    Vespa PM, Miller C, McArthur D, et al. Nonconvulsive electrographic seizures after traumatic brain injury result in a delayed prolonged increase in intracranial pressure and metabolic crisis. Crit Care Med. 2007;35(12):2830–6.CrossRefPubMedCentralPubMedGoogle Scholar
  24. 24.
    Flores-Cordero JM, Amaya-Villar R, Rincon-Ferrari MD, et al. Acute community-acquired bacterial meningitis in adults admitted to the intensive care unit. Clinical manifestations, management and prognostic factors. Intensive Care Med. 2003;29(11):1967–73.CrossRefPubMedGoogle Scholar
  25. 25.
    Zoons E, Weisfelt M, de Gans J, et al. Seizures in adults with bacterial meningitis. Neurology. 2008;70(22):2109–15.CrossRefPubMedGoogle Scholar
  26. 26.
    Machio M, Dinapoli L. Patient with brain tumor-related epilepsy. J Neurooncol. 2012;109(1):1–6.CrossRefGoogle Scholar
  27. 27.
    Cocito L, Audenino D. Altered mental status in patients with cancer. Arch Neurol. 2001;58(8):1310–2.CrossRefPubMedGoogle Scholar
  28. 28.
    Spindler M, Jacks LM, Chen X, Panageas K, DeAngelis LM, Avila EK. Spectrum of nonconvulsive status epilepticus in patients with cancer. J of Clin Neurophysiol. 2013;30(4):339–43.CrossRefGoogle Scholar
  29. 29.
    Carrera E, Claassen J, Oddo M, Emerson G, Mayer SA, Hirsch LJ. Continuous electroencephalographic monitoring in critically ill patients with central nervous system infections. Arch Neurol. 2008;65(12):1612–8.PubMedGoogle Scholar
  30. 30.
    Trieiman DM, Walker MC. Treatment of seizure emergencies: convulsive and non-convulsive status epilepticus. Epilepsy Res. 2006;68(Suppl1):S77–82.CrossRefGoogle Scholar
  31. 31.
    Vespa PM. Multimodality monitoring and telemonitoring in neurocritical care: from microdialysis to robotic telepresence. Curr Opin Crit Care. 2005;11(2):133–8.CrossRefPubMedGoogle Scholar
  32. 32.
    Ronne-Engstrom E, Winkler T. Continuous EEG monitoring in patients with traumatic brain injury reveals a high incidence of epileptiform activity. Acta Neurol Scand. 2006;114(1):47–53.CrossRefPubMedGoogle Scholar
  33. 33.
    Mirski MA, Varelas PN. Seizures and status epilepticus in the critically Ill. Crit Care Clin. 2008;24(1):115–47.CrossRefPubMedGoogle Scholar
  34. 34.
    Mecarelli O, Pro S, Randi F, et al. EEG patterns and epileptic seizures in acute phase of stroke. Cerebrovasc Dis. 2011;31(2):191–8.CrossRefPubMedGoogle Scholar
  35. 35.
    Vespa PM, O’Phelan K, Shah M, et al. Acute seizures after intracerebral hemorrhage: a factor in progressive midline shift and outcome. Neurology. 2003;60(9):1441–6.CrossRefPubMedGoogle Scholar
  36. 36.
    Dennis LJ, Claassen J, Hirsch LJ, et al. Nonconvulsive status epilepticus after subarachnoid hemorrhage. Neurosurgery. 2002;51(5):1136–44.CrossRefPubMedGoogle Scholar
  37. 37.
    Claassen J, Mayer SA, Hirsch LJ. Continuous EEG monitoring in patients with subarachnoid hemorrhage. J Clin Neurophysiol. 2005;22:92–8.CrossRefPubMedGoogle Scholar
  38. 38.
    Little AS, Kerrigan JF, McDougall CG, Zabramski JM, Albuguerque FC, Nakaji P, Spetzler RF. Nonconvulsive status epilepticus in patients suffering spontaneous subarachnoid hemorrhage. J Neurosurg. 2007;106(5):805–11.CrossRefPubMedGoogle Scholar
  39. 39.
    Claassen J, Jette N, Chum F, et al. Electrographic seizures and periodic discharges after intracerebral hemorrhage. Neurology. 2007;69(13):1356–65.CrossRefPubMedGoogle Scholar
  40. 40.
    Rossetti AP, Logroscino G, Broomfield EB. Refractory status epilepticus: effect of treatment aggressiveness on prognosis. Arch Neurol. 2005;62(11):1698–702.CrossRefPubMedGoogle Scholar
  41. 41.
    Treiman DM, Walton NY, Collins JY, et al. A comparison of four treatments for generalized convulsive status epilepticus. Veterans Affairs Status Epilepticus Cooperatie Study Group. N Engl J Med. 1998;339(12):792–8.CrossRefPubMedGoogle Scholar
  42. 42.
    Lowenstein DH, Alldredge BK. Status epilepticus. N Engl J Med. 1998;338(14):970–6.CrossRefPubMedGoogle Scholar
  43. 43.
    Meierkord H, Boon P, Engelsen B, et al. EFNS guideline on the management of status epilepticus in adults. Eur J Neurol. 2010;17(3):348–55.CrossRefPubMedGoogle Scholar
  44. 44.
    Holtkamp M, Othman J, Buchheim K, Meierkord H. Predictors and prognosis of refractory status epilepticus treated in a neurological intensive care unit. J Neurol Neurosurg Psychiatry. 2005;76(4):534–9.CrossRefPubMedCentralPubMedGoogle Scholar
  45. 45.
    Brophy GM, Bell R, Claassen J, et al. Guidelines for the evaluation and management of status epilpeitcus. Neuro Crit Care. 2012;17(1):3–23.CrossRefGoogle Scholar
  46. 46.
    Sutter R, Marsch S, Fuhr P, Kaplan PW, Ruegg S. Anesthetic drugs in status epilepticus. A 6-year cohort study. Neurology. 2014;82(8):656–64.CrossRefPubMedCentralPubMedGoogle Scholar
  47. 47.
    Narayanan JT, Murthy JM. Nonconvulsive status epilepticus in a neurological Intensive care unit: profile in a developing country. Epilepsia. 2007;48(5):900–6.CrossRefPubMedGoogle Scholar
  48. 48.
    Beniczky S, Hirsch LJ, Kaplan PW, et al. Unified EEG terminology and criteria for nonconvulsive status epilepticus. Epilepsia. 2013;54(Suppl 6):28–9.CrossRefPubMedGoogle Scholar
  49. 49.
    Ney JP, Van Der Goes DN, Nuwer MR, Nelson L, Eccher M. Continuous and routine EEG in Intensive Care. Utilization and outcomes, United States 2005–2009. Neurology. 2013;81(23):2002–8.CrossRefPubMedCentralPubMedGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Ikuko Laccheo
    • 1
    • 2
  • Hasan Sonmezturk
    • 3
  • Amar B. Bhatt
    • 3
  • Luke Tomycz
    • 4
  • Yaping Shi
    • 3
  • Marianna Ringel
    • 3
  • Gina DiCarlo
    • 3
  • DeAngelo Harris
    • 3
  • John Barwise
    • 3
  • Bassel Abou-Khalil
    • 3
  • Kevin F. Haas
    • 3
  1. 1.Epilepsy Center of ExcellenceVeterans Affairs Medical CenterRichmondUSA
  2. 2.Virginia Commonwealth UniversityRichmondUSA
  3. 3.Vanderbilt University Medical CenterNashvilleUSA
  4. 4.Seattle Children’s HospitalSeattleUSA

Personalised recommendations