title: Rhythmic electrographic discharges during deep hypothermic circulatory arrest.
abstract: OBJECTIVE
  The main objective of this study is to examine the prevalence and timing of rhythmic electrographic discharges and periodic sharp transients during aortic arch repair surgeries using DHCA as detected by continuous intraoperative encephalogram (EEG) and correlate it with outcome.
  
  
  METHODS
  Electronic medical records and the intraoperative EEGs of 32 patients who underwent aortic arch reconstruction with DHCA were reviewed. Preoperative patient characteristics, intraoperative data, and postoperative outcomes were examined. EEGs were graded based on the frequency of sharp transients (grade 0-2) and/or the presence of rhythmic electrographic discharges (grade 3).
  
  
  RESULTS
  Periodic sharp transients were seen in 30/32 cases. Grade 1 and grade 2 activations were more prominent during cooling at nasopharyngeal temperature of 23.9±4.01 °C (mean±SDV). Rhythmic electrographic discharges occurred in seven patients and were exclusively seen during cooling at nasopharyngeal temperatures below 28 °C except in one case during rewarming at nasopharyngeal temperatures of 22°C. No patient with rhythmic discharges developed postoperative clinical neurologic deficit or seizures.
  
  
  CONCLUSIONS
  Periodic sharp transients occurred in almost all cases during induction of deep hypothermia. This activity was not associated with postoperative neurologic deficit.
  
  
  CONCLUSIONS
  Clinical neurophysiologists, technicians and surgeons need to be aware that low amplitude periodic sharp transients and rhythmic electrographic discharges are common during DHCA, yet have no apparent clinical significance.
authors.affiliation: Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA. Electronic address: Feyissa.Anteneh@mayo.edu.
authors.forename: Anteneh M
authors.initials: AM
authors.lastname: Feyissa
authors.affiliation: Department of Cardiovascular Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA. Electronic address: Pochettino.Alberto@mayo.edu.
authors.forename: Alberto
authors.initials: A
authors.lastname: Pochettino
authors.affiliation: Department of Vascular Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA. Electronic address: bower.thomas@mayo.edu.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Bower
authors.affiliation: Department of Anesthesia, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA. Electronic address: gnuttall@mayo.edu.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Nuttall
authors.affiliation: Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA. Electronic address: britton.jeffrey@mayo.edu.
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Britton
mesh_terms: D000368:Aged; D002560:Cerebrovascular Circulation / Q000502:physiology; D050792:Circulatory Arrest, Deep Hypothermia Induced / Q000379:methods / Q000639:trends*; D004569:Electroencephalography / Q000379:methods / Q000639:trends*; D005260:Female; D006801:Humans; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods / Q000639:trends*; D008297:Male; D008875:Middle Aged; D010507:Periodicity; D012189:Retrospective Studies
keywords: Aortic arch repair; Deep hypothermia; EEG; Intraoperative EEG monitoring; Rhythmic electrographic discharges; Sharp transients; Status epilepticus; Therapeutic hypothermia