Current Neurology and Neuroscience Reports

, Volume 5, Issue 4, pp 312–321 | Cite as

Continuous electroencephalogram monitoring in critically ill patients

  • Nathalie Jette
  • Lawrence J. Hirsch


The past few years have witnessed remarkable advances in continuous EEG monitoring (cEEG). The indications and applications for cEEG are broadening, including detection of nonconvulsive seizures, spell characterization, and prognostication. Seizures are common in the critically ill, are usually nonconvulsive, and can easily be missed without cEEG. Interpretation and clinical management of the complex periodic and rhythmic EEG patterns commonly identified in these patients require further study. With the use of quantitative analysis techniques, cEEG can detect cerebral ischemia very early, before permanent neuronal injury occurs. This article reviews the indications and recent advances in cEEG in critically ill patients. Continuous brain monitoring with cEEG is rapidly becoming the standard of care in critically ill patients with neurologic impairment.


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References and Recommended Reading

  1. 1.
    Hirsch LJ: Continuous EEG monitoring in the intensive care unit: an overview. J Clin Neurophysiol 2004, 21:332–340.PubMedGoogle Scholar
  2. 2.
    Pandian JD, Cascino GD, So EL, et al.: Digital video-electroencephalographic monitoring in the neurological-neurosurgical intensive care unit: clinical features and outcome. Arch Neurol 2004, 61:1090–1094.PubMedCrossRefGoogle Scholar
  3. 3.
    Scheuer ML: Continuous EEG monitoring in the intensive care unit. Epilepsia 2002, 43(Suppl 3):114–127.PubMedCrossRefGoogle Scholar
  4. 4.
    Jordan KG: Continuous EEG and evoked potential monitoring in the neuroscience intensive care unit. J Clin Neurophysiol 1993, 10:445–475.PubMedCrossRefGoogle Scholar
  5. 5.
    DeLorenzo RJ, Waterhouse EJ, Towne AR, et al.: Persistent nonconvulsive status epilepticus after the control of convulsive status epilepticus. Epilepsia 1998, 39:833–840.PubMedCrossRefGoogle Scholar
  6. 6.
    Claassen J, Mayer SA, Kowalski RG, et al.: Detection of electrographic seizures with continuous EEG monitoring in critically ill patients. Neurology 2004, 62:1743–1748. These investigators found that cEEG detected seizure activity in 19% of 570 patients but that most (92%) were nonconvulsive. Coma, age younger than 18 years, a history of epilepsy, and convulsive seizures prior to monitoring were risk factors for electrographic seizures.PubMedGoogle Scholar
  7. 7.
    Claassen J, Hirsch LJ, Emerson RG, et al.: Continuous EEG monitoring and midazolam infusion for refractory nonconvulsive status epilepticus. Neurology 2001, 57:1036–1042.PubMedGoogle Scholar
  8. 8.
    Privitera M, Hoffman M, Moore JL, Jester D: EEG detection of nontonic-clonic status epilepticus in patients with altered consciousness. Epilepsy Res 1994, 18:155–166.PubMedCrossRefGoogle Scholar
  9. 9.
    Jaitly R, Sgro JA, Towne AR, et al.: Prognostic value of EEG monitoring after status epilepticus: a prospective adult study. J Clin Neurophysiol 1997, 14:326–334.PubMedCrossRefGoogle Scholar
  10. 10.
    Young GB, Jordan KG, Doig GS: An assessment of nonconvulsive seizures in the intensive care unit using continuous EEG monitoring: an investigation of variables associated with mortality. Neurology 1996, 47:83–89.PubMedGoogle Scholar
  11. 11.
    Dennis LJ, Claassen J, Hirsch LJ, et al.: Nonconvulsive status epilepticus after subarachnoid hemorrhage. Neurosurgery 2002, 51:1136–1143.PubMedCrossRefGoogle Scholar
  12. 12.
    Jordan KG: Emergency EEG and continuous EEG monitoring in acute ischemic stroke. J Clin Neurophysiol 2004, 21:341–352.PubMedGoogle Scholar
  13. 13.
    Astrup J, Siesjo BK, Symon L: Thresholds in cerebral ischemia -the ischemic penumbra. Stroke 1981, 12:723–725.PubMedGoogle Scholar
  14. 14.
    Claassen J, Hirsch LJ, Kreiter KT, et al.: Quantitative continuous EEG for detecting delayed cerebral ischemia in patients with poor-grade subarachnoid hemorrhage. Clin Neurophysiol 2004, 115:2699–2710.PubMedCrossRefGoogle Scholar
  15. 15.
    Vespa PM, Nuwer MR, Juhasz C, et al.: Early detection of vasospasm after acute subarachnoid hemorrhage using continuous EEG ICU monitoring. Electroencephalogr Clin Neurophysiol 1997, 103:607–615.PubMedCrossRefGoogle Scholar
  16. 16.
    Treiman DM, Meyers PD, Walton NY, et al.: A comparison of four treatments for generalized convulsive status epilepticus. Veterans Affairs Status Epilepticus Cooperative Study Group. N Engl J Med 1998, 339:792–798.PubMedCrossRefGoogle Scholar
  17. 17.
    Jordan KG: Neurophysiologic monitoring in the neuroscience intensive care unit. Neurol Clin 1995, 13:579–626.PubMedGoogle Scholar
  18. 18.
    Sankar R, Shin DH, Wasterlain CG: Serum neuron-specific enolase is a marker for neuronal damage following status epilepticus in the rat. Epilepsy Res 1997, 28:129–136.PubMedCrossRefGoogle Scholar
  19. 19.
    DeGiorgio CM, Heck CN, Rabinowicz AL, et al.: Serum neuronspecific enolase in the major subtypes of status epilepticus. Neurology 1999, 52:746–749.PubMedGoogle Scholar
  20. 20.
    Kaplan PW: Nonconvulsive status epilepticus in the emergency room. Epilepsia 1996, 7:643–650.CrossRefGoogle Scholar
  21. 21.
    Jordan KG, Young GB, Doig GS: Delays in emergency department (ED) diagnosis and treatment of nonconvulsive status epilepticus (NCSE). Neurology 1995, 45(Suppl 4):A346.Google Scholar
  22. 22.
    Towne AR, Waterhouse EJ, Boggs JG, et al.: Prevalence of nonconvulsive status epilepticus in comatose patients. Neurology 2000, 54:340–345. The researchers found that nonconvulsive status epilepticus is an underrecognized cause of coma, occurring in 8% of 236 comatose patients without signs of seizure activity. Thus, patients with unexplained coma should have an EEG.PubMedGoogle Scholar
  23. 23.
    Vespa PM, O’Phelan K, Shah M, et al.: Acute seizures after intracerebral hemorrhage: a factor in progressive midline shift and outcome. Neurology 2003, 60:1441–1446. This group found that seizures after ICH, most of which were nonconvulsive, were associated with increased brain edema and midline shift, even after controlling for hemorrhage size. There was also a trend towards worse outcome in those with seizures.PubMedGoogle Scholar
  24. 24.
    Hartings JA, Williams AJ, Tortella FC: Occurrence of nonconvulsive seizures, periodic epileptiform discharges, and intermittent rhythmic delta activity in rat focal ischemia. Exp Neurol 2003, 179:139–149.PubMedCrossRefGoogle Scholar
  25. 25.
    Williams AJ, Tortella FC, Lu XM, et al.: Antiepileptic drug treatment of nonconvulsive seizures induced by experimental focal brain ischemia. J Pharmacol Exp Ther 2004, 311:220–227.PubMedCrossRefGoogle Scholar
  26. 26.
    Mirsattari SM, Lee DH, Jones D, et al.: MRI compatible EEG electrode system for routine use in the epilepsy monitoring unit and intensive care unit. Clin Neurophysiol 2004, 115:2175–2180.PubMedCrossRefGoogle Scholar
  27. 27.
    Ives JR: New chronic EEG electrode for CCU/ICU monitoring. J Clin Neurophysiol 2005, 22:119–123.PubMedCrossRefGoogle Scholar
  28. 28.
    Labar DR, Fisch BJ, Pedley TA, et al.: Quantitative EEG monitoring for patients with subarachnoid hemorrhage. Electroencephalogr Clin Neurophysiol 1991, 78:325–332.PubMedCrossRefGoogle Scholar
  29. 29.
    Hauser WA, Tabaddor K, Factor PR, Finer C: Seizures and head injury in an urban community. Neurology 1984, 34:746–751.PubMedGoogle Scholar
  30. 30.
    Lee ST, Lui TN, Wong CW, et al.: Early seizures after moderate closed head injury. Acta Neurochir (Wien) 1995, 137:151–154.CrossRefGoogle Scholar
  31. 31.
    Da Silva AM, Vaz AR, Mendonca D: Posttraumatic epilepsy in civilians: clinical and electroencephalographic studies. Acta Neurochir (Wien) 1992, 55:56–63.Google Scholar
  32. 32.
    Young GB: Seizures in comatose patients in ICU: differential effects of etiology. Neurocrit Care 2005, In press.Google Scholar
  33. 33.
    Vespa PM, Nuwer MR, Nenov V, et al.: Increased incidence and impact of nonconvulsive and convulsive seizures after traumatic brain injury as detected by continuous electroencephalographic monitoring. J Neurosurg 1999, 91:750–760.PubMedGoogle Scholar
  34. 34.
    Vespa PM, Boscardin WJ, Hovda DA, et al.: Early and persistent impaired percent alpha variability on continuous electroencephalography monitoring as predictive of poor outcome after traumatic brain injury. J Neurosurg 2002, 97:84–92.PubMedCrossRefGoogle Scholar
  35. 35.
    Kassell NF, Hitchon PW, Gerk MK, et al.: Alterations in cerebral blood flow, oxygen metabolism, and electrical activity produced by high dose sodium thiopental. Neurosurgery 1980, 7:598–603.PubMedCrossRefGoogle Scholar
  36. 36.
    Jette N, Claassen J, Weintraub D, et al.: Time to first seizure in critically ill pediatric patients undergoing continuous EEG monitoring. Epilepsia 2004, 45(Suppl 1):245.Google Scholar
  37. 37.
    Scheuer ML, Wilson SB: Data analysis for continuous EEG monitoring in the ICU: seeing the forest and the trees. J Clin Neurophysiol 2004, 21:353–378.PubMedGoogle Scholar
  38. 38.
    van Putten MJ, Tavy DL: Continuous quantitative EEG monitoring in hemispheric stroke patients using the brain symmetry index. Stroke 2004, 35:2489–2492.PubMedCrossRefGoogle Scholar
  39. 39.
    van Putten MJ, Peters JM, Mulder SM, et al.: A brain symmetry index (BSI) for online EEG monitoring in carotid endarterectomy. Clin Neurophysiol 2004, 115:1189–1194.PubMedCrossRefGoogle Scholar
  40. 40.
    Wartenberg KA, Mayer SA: Multimodal brain monitoring in the neurological intensive care unit: where does continuous EEG fit in? J Clin Neurophysiol 2005, 22:124–127.PubMedCrossRefGoogle Scholar
  41. 41.
    Vespa PM, McArthur D, O’Phelan K, et al.: Persistently low extracellular glucose correlates with poor outcome 6 months after human traumatic brain injury despite a lack of increased lactate: a microdialysis study. J Cereb Blood Flow Metab 2003, 23:865–877.PubMedCrossRefGoogle Scholar
  42. 42.
    Vespa P, Martin NA, Nenov V, et al.: Delayed increase in extracellular glycerol with post-traumatic electrographic epileptic activity: support for the theory that seizures induce secondary injury. Acta Neurochir Suppl 2002, 81:355–357.PubMedGoogle Scholar
  43. 43.
    Nilsson P, Ronne-Engstrom E, Flink R, et al.: Epileptic seizure activity in the acute phase following cortical impact trauma in rat. Brain Res 1994, 637:227–232.PubMedCrossRefGoogle Scholar
  44. 44.
    Sakowitz OW, Unterberg AW, Stover JF: Neuronal activity determined by quantitative EEG and cortical microdialysis is increased following controlled cortical impact injury in rats. Acta Neurochir Suppl 2002, 81:221–223.PubMedGoogle Scholar
  45. 45.
    Ono K, Iwatsuki N, Tajima T, et al.: Elevation of the extracellular glutamate concentration in the hippocampus after total cerebral ischemia related to the deterioration of the recovery in EEG and evoked potentials in dogs. J Anesth 1993, 7:334–340.PubMedCrossRefGoogle Scholar
  46. 46.
    Thomas PM, Phillips JP, O’Connor WT: Hippocampal microdialysis during spontaneous intraoperative epileptiform activity. Acta Neurochir (Wien) 2004, 146:143–151.CrossRefGoogle Scholar
  47. 47.
    Thomas PM, Phillips JP, Delanty N, O’Connor WT: Elevated extracellular levels of glutamate, aspartate and gamma-aminobutyric acid within the intraoperative, spontaneously epileptiform human hippocampus. Epilepsy Res 2003, 54:73–79.PubMedCrossRefGoogle Scholar
  48. 48.
    Wilson CL, Maidment NT, Shomer MH, et al.: Comparison of seizure related amino acid release in human epileptic hippocampus versus a chronic, kainate rat model of hippocampal epilepsy. Epilepsy Res 1996, 26:245–254.PubMedCrossRefGoogle Scholar
  49. 49.
    During MJ, Fried I, Leone P, et al.: Direct measurement of extracellular lactate in the human hippocampus during spontaneous seizures. J Neurochem 1994, 62:2356–2361.PubMedCrossRefGoogle Scholar
  50. 50.
    During MJ, Spencer DD: Extracellular hippocampal glutamate and spontaneous seizure in the conscious human brain. Lancet 1993, 341:1607–1610.PubMedCrossRefGoogle Scholar
  51. 51.
    Hirsch LJ, Claassen J, Mayer SA, Emerson RG: Stimulusinduced rhythmic, periodic, or ictal discharges (SIRPIDs): a common EEG phenomenon in the critically ill. Epilepsia 2004, 45:109–123.PubMedCrossRefGoogle Scholar
  52. 52.
    Shaner DM, McCurdy SA, Herring MO, Gabor AJ: Treatment of status epilepticus: a prospective comparison of diazepam and phenytoin versus phenobarbital and optional phenytoin. Neurology 1988, 38:202–207.PubMedGoogle Scholar
  53. 53.
    Chamberlain JM, Altieri MA, Futterman C, et al.: A prospective, randomized study comparing intramuscular midazolam with intravenous diazepam for the treatment of seizures in children. Pediatr Emerg Care 1997, 13:92–94.PubMedCrossRefGoogle Scholar
  54. 54.
    Alldredge BK, Gelb AM, Isaacs SM, et al.: A comparison of lorazepam, diazepam, and placebo for the treatment of out-ofhospital status epilepticus. N Engl J Med 2001, 345:631–637.PubMedCrossRefGoogle Scholar
  55. 55.
    Scott RC, Besag FM, Neville BG: Buccal midazolam and rectal diazepam for treatment of prolonged seizures in childhood and adolescence: a randomised trial. Lancet 1999, 353:623–626.PubMedCrossRefGoogle Scholar
  56. 56.
    Lahat E, Goldman M, Barr J, et al.: Comparison of intranasal midazolam with intravenous diazepam for treating febrile seizures in children: prospective randomised study. BMJ 2000, 321:83–86.PubMedCrossRefGoogle Scholar
  57. 57.
    Leppik IE, Derivan AT, Homan RW, et al.: Double-blind study of lorazepam and diazepam in status epilepticus. JAMA 1983, 249:1452–1454.PubMedCrossRefGoogle Scholar
  58. 58.
    Chong DJ, Hirsch LJ: Which EEG patterns warrant treatment in the critically ill? Reviewing the evidence for treatment of periodic epileptiform discharges and related patterns. J Clin Neurophysiol 2005, 22:79–91.PubMedCrossRefGoogle Scholar
  59. 59.
    Hirsch LJ, Kull LL: Continuous EEG monitoring in the intensive care unit. Am J Electroneurodiagnostic Technol 2004, 44:137–158.PubMedGoogle Scholar

Copyright information

© Current Science Inc 2005

Authors and Affiliations

  • Nathalie Jette
  • Lawrence J. Hirsch
    • 1
  1. 1.Comprehensive Epilepsy Center, Columbia UniversityNew YorkUSA

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