Early haemodynamic changes observed in patients with epilepsy, in a visual experiment and in simulations

Research output: Contribution to journalArticle

Authors

  • David T. Rollings
  • Dirk Ostwald
  • Dougall Mccorry
  • Manny Bagary
  • Imad Soryal

External organisations

  • Center for Cognitive Neuroscience Berlin, Department of Education and Psychology, Freie Universität Berlin, Berlin, Germany
  • Newcastle University
  • Department of Neuroscience, Queen Elizabeth Hospital Birmingham, Edgbaston, Birmingham, UK
  • Department of Neuropsychiatry, The Barberry, Birmingham, UK

Abstract

Objective

The objective of this study was to investigate whether previously reported early blood oxygen level dependent (BOLD) changes in epilepsy could occur as a result of the modelling techniques rather than physiological changes.

Methods

EEG-fMRI data were analysed from seven patients with focal epilepsy, six control subjects undergoing a visual experiment, in addition to simulations. In six separate analyses the event timing was shifted by either −9,−6,−3,+3,+6 or +9 s relative to the onset of the interictal epileptiform discharge (IED) or stimulus.

Results

The visual dataset and simulations demonstrated an overlap between modelled haemodynamic response function (HRF) at event onset and at ±3 s relative to onset, which diminished at ±6 s. Pre-spike analysis at −6 s improved concordance with the assumed IED generating lobe relative to the standard HRF in 43% of patients.

Conclusion

The visual and simulated dataset findings indicate a form of “temporal bleeding”, an overlap between the modelled HRF at time 0 and at ±3 s which attenuated at ±6 s. Pre-spike analysis at −6 s may improve concordance.

Significance

This form of analysis should be performed at 6 s prior to onset of IED to minimise temporal bleeding effect. The results support the presence of relevant BOLD responses occurring prior to IEDs.

Details

Original languageEnglish
Pages (from-to)245-253
JournalClinical Neurophysiology
Volume127
Issue number1
Early online date17 Jul 2015
Publication statusPublished - Jan 2016

Keywords

  • Visual stimulation, Pre-spike response, Epilepsy, Haemodynamic response function, simulations, EEG-fMRI