Multivariate linear discrimination of seizures.
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.
Jerger
Kristin K
KK
Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA.
Weinstein
Steven L
SL
Sauer
Tim
T
Schiff
Steven J
SJ
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
D000927:Anticonvulsants