title: The probability of seizures during EEG monitoring in critically ill adults.
abstract: OBJECTIVE
  To characterize the risk for seizures over time in relation to EEG findings in hospitalized adults undergoing continuous EEG monitoring (cEEG).
  
  
  METHODS
  Retrospective analysis of cEEG data and medical records from 625 consecutive adult inpatients monitored at a tertiary medical center. Using survival analysis methods, we estimated the time-dependent probability that a seizure will occur within the next 72-h, if no seizure has occurred yet, as a function of EEG abnormalities detected so far.
  
  
  RESULTS
  Seizures occurred in 27% (168/625). The first seizure occurred early (<30min of monitoring) in 58% (98/168). In 527 patients without early seizures, 159 (30%) had early epileptiform abnormalities, versus 368 (70%) without. Seizures were eventually detected in 25% of patients with early epileptiform discharges, versus 8% without early discharges. The 72-h risk of seizures declined below 5% if no epileptiform abnormalities were present in the first two hours, whereas 16h of monitoring were required when epileptiform discharges were present. 20% (74/388) of patients without early epileptiform abnormalities later developed them; 23% (17/74) of these ultimately had seizures. Only 4% (12/294) experienced a seizure without preceding epileptiform abnormalities.
  
  
  CONCLUSIONS
  Seizure risk in acute neurological illness decays rapidly, at a rate dependent on abnormalities detected early during monitoring. This study demonstrates that substantial risk stratification is possible based on early EEG abnormalities.
  
  
  CONCLUSIONS
  These findings have implications for patient-specific determination of the required duration of cEEG monitoring in hospitalized patients.
authors.affiliation: Department of Neurology, Epilepsy Service, Massachusetts General Hospital, Wang 720, Boston, MA 02114, USA. Electronic address: mwestover@mgh.harvard.edu.
authors.forename: M Brandon
authors.initials: MB
authors.lastname: Westover
authors.affiliation: Department of Neurology, Epilepsy Service, Massachusetts General Hospital, Wang 720, Boston, MA 02114, USA; Department of Neurology, Epilepsy Service, Beth Israel Deaconess Medical Center, West/Baker 5, Boston, MA 02214, USA. Electronic address: mshafi@bidmc.harvard.edu.
authors.forename: Mouhsin M
authors.initials: MM
authors.lastname: Shafi
authors.affiliation: Department of Neurology, Epilepsy Service, Massachusetts General Hospital, Wang 720, Boston, MA 02114, USA. Electronic address: mtbianchi@mgh.harvard.edu.
authors.forename: Matt T
authors.initials: MT
authors.lastname: Bianchi
authors.affiliation: Department of Neurology, Epilepsy Service, Massachusetts General Hospital, Wang 720, Boston, MA 02114, USA. Electronic address: lmoura@mgh.harvard.edu.
authors.forename: Lidia M V R
authors.initials: LM
authors.lastname: Moura
authors.affiliation: Department of Neurology, Epilepsy Service, Massachusetts General Hospital, Wang 720, Boston, MA 02114, USA. Electronic address: daorourke@mgh.harvard.edu.
authors.forename: Deirdre
authors.initials: D
authors.lastname: O'Rourke
authors.affiliation: Department of Neurology, Epilepsy Service, Massachusetts General Hospital, Wang 720, Boston, MA 02114, USA. Electronic address: erosenthal@mgh.harvard.edu.
authors.forename: Eric S
authors.initials: ES
authors.lastname: Rosenthal
authors.affiliation: Department of Neurology, Epilepsy Service, Massachusetts General Hospital, Wang 720, Boston, MA 02114, USA. Electronic address: cchu3@mgh.harvard.edu.
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Chu
authors.affiliation: Department of Neurology, Epilepsy Service, Massachusetts General Hospital, Wang 720, Boston, MA 02114, USA.
authors.forename: Samantha
authors.initials: S
authors.lastname: Donovan
authors.affiliation: Department of Neurology, Epilepsy Service, Massachusetts General Hospital, Wang 720, Boston, MA 02114, USA. Electronic address: dbhoch@mgh.harvard.edu.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Hoch
authors.affiliation: Department of Neurology, Epilepsy Service, Massachusetts General Hospital, Wang 720, Boston, MA 02114, USA. Electronic address: rkilbride@mgh.harvard.edu.
authors.forename: Ronan D
authors.initials: RD
authors.lastname: Kilbride
authors.affiliation: Department of Neurology, Epilepsy Service, Massachusetts General Hospital, Wang 720, Boston, MA 02114, USA. Electronic address: acole1@mgh.harvard.edu.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Cole
authors.affiliation: Department of Neurology, Epilepsy Service, Massachusetts General Hospital, Wang 720, Boston, MA 02114, USA. Electronic address: scash@mgh.harvard.edu.
authors.forename: Sydney S
authors.initials: SS
authors.lastname: Cash
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002540:Cerebral Cortex / Q000503:physiopathology*; D016638:Critical Illness; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012640:Seizures / Q000175:diagnosis* / Q000503:physiopathology; D055815:Young Adult
keywords: Continuous electroencephalography; ICU EEG monitoring; Nonconvulsive seizures
references.citation: Ann Neurol. 1993 Mar;33(3):286-91
references.pmid: 8498812
references.citation: Neurology. 2007 Sep 25;69(13):1356-65
references.pmid: 17893296
references.citation: J Clin Neurophysiol. 2004 Sep-Oct;21(5):332-40
references.pmid: 15592007
references.citation: J Clin Neurophysiol. 2013 Feb;30(1):1-27
references.pmid: 23377439
references.citation: J Clin Neurophysiol. 2005 Apr;22(2):79-91
references.pmid: 15805807
references.citation: Arch Neurol. 2002 Feb;59(2):205-10
references.pmid: 11843690
references.citation: Neurology. 2000 Jan 25;54(2):340-5
references.pmid: 10668693
references.citation: Acta Neurochir (Wien). 1995;137(3-4):151-4
references.pmid: 8789655
references.citation: Semin Neurol. 2006 Sep;26(4):396-402
references.pmid: 16969740
references.citation: Can J Neurol Sci. 1980 Nov;7(4):285-90
references.pmid: 7214242
references.citation: Neurology. 2012 Oct 23;79(17):1796-801
references.pmid: 23054233
references.citation: J Clin Neurophysiol. 1999 Jul;16(4):341-52; discussion 353
references.pmid: 10478707
references.citation: Neurology. 2010 Aug 31;75(9):792-8
references.pmid: 20805525
references.citation: J Clin Neurophysiol. 2005 Apr;22(2):99-106
references.pmid: 15805809
references.citation: Neurology. 2001 Sep 25;57(6):1036-42
references.pmid: 11571331
references.citation: N Engl J Med. 1990 Aug 23;323(8):497-502
references.pmid: 2115976
references.citation: Neurology. 1995 Nov;45(11):1962-4
references.pmid: 7501141
references.citation: Neurology. 1988 Mar;38(3):401-5
references.pmid: 3347343
references.citation: Arch Neurol. 2006 Dec;63(12):1750-5
references.pmid: 17172615
references.citation: Epilepsia. 1998 Aug;39(8):833-40
references.pmid: 9701373
references.citation: Neurosurgery. 1995 Nov;37(5):863-70; discussion 870-1
references.pmid: 8559333
references.citation: J Clin Neurophysiol. 1993 Oct;10(4):445-75
references.pmid: 8308143
references.citation: Neurology. 2000 Nov 14;55(9):1315-20
references.pmid: 11087774
references.citation: Neurology. 1980 Jul;30(7 Pt 1):683-9
references.pmid: 7190235
references.citation: Can J Neurol Sci. 1986 Aug;13(3):229-31
references.pmid: 3742338
references.citation: Neurosurgery. 1983 Jan;12(1):14-7
references.pmid: 6828220
references.citation: Neurol India. 2003 Dec;51(4):453-4
references.pmid: 14742920
references.citation: Arch Neurol. 1998 Jan;55(1):117-9
references.pmid: 9443718
references.citation: Acta Neurochir (Wien). 1981;55(3-4):253-64
references.pmid: 7234531
references.citation: Epilepsy Res. 1994 Jun;18(2):155-66
references.pmid: 7957038
references.citation: J Clin Neurophysiol. 1999 Jan;16(1):14-39
references.pmid: 10082089
references.citation: Arch Neurol. 2008 Dec;65(12):1612-8
references.pmid: 19064748
references.citation: Neurology. 2011 Mar 22;76(12):1071-7
references.pmid: 21307352
references.citation: Neurology. 2003 May 13;60(9):1441-6
references.pmid: 12743228
references.citation: J Neurosurg. 1999 Nov;91(5):750-60
references.pmid: 10541231
references.citation: Neurology. 2004 May 25;62(10):1743-8
references.pmid: 15159471