title: Multivariate linear discrimination of seizures.
abstract: OBJECTIVE
  To discriminate seizures from interictal dynamics based on multivariate synchrony measures, and to identify dynamics of a pre-seizure state.
  
  
  METHODS
  A linear discriminator was constructed from two different measures of synchronization: cross-correlation and phase synchronization. We applied this discriminator to a sequence of seizures recorded from the intracranial EEG of a patient monitored over 6 days.
  
  
  RESULTS
  Surprisingly, we found that this bivariate measure of synchronization was not a reliable seizure discriminator for 7 of 9 seizures. Furthermore, the method did not appear to reliably detect a pre-seizure state. An association between anti-convulsant dosage, frequency of clinical seizures, and discriminator performance was noted.
  
  
  CONCLUSIONS
  Using a bivariate measure of synchronization failed to reliably differentiate seizures from non-seizure periods in these data, nor did such methods show reliable detection of a synchronous pre-seizure state. The non-stationary variables of decreasing antiepileptic medication (without available serum concentration measurements), and concomitant increasing seizure frequency contributed to the difficulties in validating a seizure prediction tool on such data.
  
  
  CONCLUSIONS
  The finding that these seizures were not a simple reflection of increasing synchronization in the EEG has important implications. The non-stationary characteristics of human post-implantation intracranial EEG is an inherent limitation of pre-resection data sets.
authors.affiliation: Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA.
authors.forename: Kristin K
authors.initials: KK
authors.lastname: Jerger
authors.forename: Steven L
authors.initials: SL
authors.lastname: Weinstein
authors.forename: Tim
authors.initials: T
authors.lastname: Sauer
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Schiff
mesh_terms: D000927:Anticonvulsants / Q000627:therapeutic use; D003344:Cortical Synchronization; D004192:Discrimination, Psychological; D004569:Electroencephalography / Q000187:drug effects; D006801:Humans; D008991:Monitoring, Physiologic; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012640:Seizures / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology*; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D013223:Statistics as Topic; D013997:Time Factors
chemical_list: D000927:Anticonvulsants