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.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Price excludes VAT (USA)
Tax calculation will be finalised during checkout.
Towne AR, Waterhouse EJ, Boggs JG, et al. Prevalence of nonconvulsive status epilepticus in comatose patients. Neurology. 2000;54(2):340–5.
Benbadis SR, Tatum WO. Prevalence of non-convulsive status epilepticus in comatose patients. Neurology. 2000;55(9):1421–3.
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.
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.
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.
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.
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.
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.
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.
Jordan KG. Continuous EEG and evoked potential monitoring in the neuroscience intensive care unit. J Clin Neurophysiol. 1993;10(4):445–75.
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.
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.
Walker MC. Status epilepticus on the intensive care unit. J Neurol. 2003;250(4):401–6.
Towne AR, Pellock JM, Ko D, DeLorenzo RJ. Determinants of mortality in status epilepticus. Epilepsia. 1994;35(1):27–34.
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.
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.
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.
Cooper AD, Britton JW, Rabinstein AA. Functional and cognitive outcome in prolonged refractory status epilepticus. Arch Neurol. 2009;66(12):1505–9.
Jordan KG, Schneider AL. Emergency “stat” EEG in the era of nonconvulsive status epilepticus. Am J Electroneurodiagnostic Technol. 2009;49(1):94–104.
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.
Kaplan PW. EEG criteria for nonconvulsive status. Epilepsia. 2007;48(suppl.8):39–41.
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.
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.
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.
Zoons E, Weisfelt M, de Gans J, et al. Seizures in adults with bacterial meningitis. Neurology. 2008;70(22):2109–15.
Machio M, Dinapoli L. Patient with brain tumor-related epilepsy. J Neurooncol. 2012;109(1):1–6.
Cocito L, Audenino D. Altered mental status in patients with cancer. Arch Neurol. 2001;58(8):1310–2.
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.
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.
Trieiman DM, Walker MC. Treatment of seizure emergencies: convulsive and non-convulsive status epilepticus. Epilepsy Res. 2006;68(Suppl1):S77–82.
Vespa PM. Multimodality monitoring and telemonitoring in neurocritical care: from microdialysis to robotic telepresence. Curr Opin Crit Care. 2005;11(2):133–8.
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.
Mirski MA, Varelas PN. Seizures and status epilepticus in the critically Ill. Crit Care Clin. 2008;24(1):115–47.
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.
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.
Dennis LJ, Claassen J, Hirsch LJ, et al. Nonconvulsive status epilepticus after subarachnoid hemorrhage. Neurosurgery. 2002;51(5):1136–44.
Claassen J, Mayer SA, Hirsch LJ. Continuous EEG monitoring in patients with subarachnoid hemorrhage. J Clin Neurophysiol. 2005;22:92–8.
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.
Claassen J, Jette N, Chum F, et al. Electrographic seizures and periodic discharges after intracerebral hemorrhage. Neurology. 2007;69(13):1356–65.
Rossetti AP, Logroscino G, Broomfield EB. Refractory status epilepticus: effect of treatment aggressiveness on prognosis. Arch Neurol. 2005;62(11):1698–702.
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.
Lowenstein DH, Alldredge BK. Status epilepticus. N Engl J Med. 1998;338(14):970–6.
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.
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.
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.
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.
Narayanan JT, Murthy JM. Nonconvulsive status epilepticus in a neurological Intensive care unit: profile in a developing country. Epilepsia. 2007;48(5):900–6.
Beniczky S, Hirsch LJ, Kaplan PW, et al. Unified EEG terminology and criteria for nonconvulsive status epilepticus. Epilepsia. 2013;54(Suppl 6):28–9.
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.
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.
Rights and permissions
About this article
Cite this article
Laccheo, I., Sonmezturk, H., Bhatt, A.B. et al. Non-convulsive Status Epilepticus and Non-convulsive Seizures in Neurological ICU Patients. Neurocrit Care 22, 202–211 (2015). https://doi.org/10.1007/s12028-014-0070-0
- Neurological ICU
- Critical care
- Altered mental status
- Non-convulsive seizures
- Non-convulsive status epilepticus