Epileptiform discharge propagation: Analyzing spikes from the onset to the peak

Clin Neurophysiol. 2016 Apr;127(4):2127-33. doi: 10.1016/j.clinph.2015.12.021. Epub 2016 Jan 12.

Abstract

Objective: To investigate how often discharge propagation occurs within the spikes recorded in patients evaluated for epilepsy surgery, and to assess its impact on the accuracy of source imaging.

Methods: Data were analyzed from 50 consecutive patients who had presurgical workup. Discharge propagation was analyzed using sequential voltage-maps of the averaged spikes, and principal components analysis. When propagation was detected, sources were modeled both at onset and peak.

Results: Propagation occurred in half of the patients. The median time of propagation between onset and peak was 17 ms. In 60% of the cases with propagation (15/25 patients) this remained in the same sub-lobar area where onset occurred. The accuracy of source imaging in cases of propagating spikes was 67% when only analyzing onset or peak. This was lower as compared to cases without propagation (79%). Combining source imaging at onset and at peak increased the accuracy to 83% for the propagating spikes.

Conclusions: Propagation occurs often in patients with focal epilepsy, evaluated for surgery. In 40% of the propagating cases, the source of onset and peak were in different sub-lobar regions.

Significance: For optimal clinical utility, sources should be modeled both at onset and at peak epochs of the spikes.

Keywords: EEG source imaging; Epilepsy surgery; Spike propagation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials* / physiology
  • Adolescent
  • Adult
  • Aged
  • Child
  • Child, Preschool
  • Electroencephalography / methods*
  • Epilepsies, Partial / diagnosis*
  • Epilepsies, Partial / physiopathology*
  • Female
  • Humans
  • Magnetoencephalography / methods*
  • Male
  • Middle Aged
  • Young Adult