title: Acute confusional state of unknown cause in the elderly: a study with continuous EEG monitoring.
abstract: BACKGROUND
  Acute confusional state (ACS) is a frequent cause of emergency consultation in the elderly. Many causes of ACS are also risk factors for seizures. Both non-convulsive seizures and status epilepticus can cause acute confusion. The yield of routine EEG may not be optimal in case of prolonged post-ictal confusion. We thus, sought to evaluate the yield of CEEG in identifying seizures in elderly patients with ACS of unknown origin.
  
  
  METHODS
  We reviewed our CEEG database for patients over 75 years with ACS and collected EEG, CEEG and clinical information.
  
  
  RESULTS
  Thirty-one percent (15/48) of the CEEG performed in elderly patients were done for ACS. Routine EEG did not reveal any epileptic anomalies in 7/15 patients. Among those, CEEG identified interictal epileptiform discharges (IED) in 2 and NCSE in 1. In 8/15 patients, routine EEG revealed epileptiform abnormalities: 3 with IED (including 1 with periodic lateralized discharges), 3 with non-convulsive seizures (NCSz) and 2 with non-convulsive status epilepticus (NCSE). Among patients with only IED, CEEG revealed NCSz in 1 and NCSE in 2.
  
  
  CONCLUSIONS
  This retrospective study suggests that NCSz and NCSE may account for more cases of ACS than what was previously thought. A single negative routine EEG does not exclude this diagnosis. Continuous EEG (CEEG) monitoring is more revealing than routine EEG for the detection of NCSE and NCSz in confused elderly. The presence of IED in the first routine EEG strongly suggests concomitant NCSz or NCSE. Prospective studies are required to further determine the role of CEEG monitoring in the assessment of ACS in the elderly and to establish the incidence of NCSz and NCSE in this setting.
authors.affiliation: Dept of Neurology, Reference Center for the Treatment of Refractory Epilepsy, Hôpital Erasme Université Libre de Bruxelles, Belgium. gillesnaeije@yahoo.com
authors.forename: Gilles
authors.initials: G
authors.lastname: Naeije
authors.forename: Nicolas
authors.initials: N
authors.lastname: Gaspard
authors.forename: Chantal
authors.initials: C
authors.lastname: Depondt
authors.forename: Thierry
authors.initials: T
authors.lastname: Pepersack
authors.forename: Benjamin
authors.initials: B
authors.lastname: Legros
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000927:Anticonvulsants / Q000627:therapeutic use; D015331:Cohort Studies; D003221:Confusion / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic; D012189:Retrospective Studies
chemical_list: D000927:Anticonvulsants