Epileptic seizures are characterized by changing signal complexity

Gregory K. Bergey, Piotr J. Franaszczuk

Research output: Contribution to journalArticle

Abstract

Objective: Epileptic seizures are brief episodic events resulting from abnormal synchronous discharges from cerebral neuronal networks. The traditional methods of signal analysis are limited by the rapidly changing nature of the EEG signal during a seizure. Time-frequency analyses, however, such as those produced by the matching pursuit (MP) method can provide continuous decompositions of recorded seizure activity. These accurate decompositions can allow for more detailed analyses of the changes in complexity of the signal that may accompany seizure evolution. Methods: The MP algorithm was applied to provide time-frequency decompositions of entire seizures recorded from depth electrode contacts in patients with intractable complex partial seizures of mesial temporal onset. The results of these analyses were compared with signals generated from the Duffing equation that represented both limit cycle and chaotic behavior. Results: Seventeen seizures from 12 different patients were analyzed. These analyses reveal that early in the seizure, the most organized, rhythmic seizure activity is more complex than limit cycle behavior, and that signal complexity increases further later in the seizure. Conclusions: Increasing complexity routinely precedes seizure termination. This may reflect progressive desynchronization.

Original languageEnglish (US)
Pages (from-to)241-249
Number of pages9
JournalClinical Neurophysiology
Volume112
Issue number2
DOIs
StatePublished - Feb 19 2001

Keywords

  • Complexity
  • Electroencephalography
  • Epilepsy
  • Seizures
  • Signal analysis
  • Termination

ASJC Scopus subject areas

  • Sensory Systems
  • Neurology
  • Clinical Neurology
  • Physiology (medical)

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