Scientific article
Open access

Optimising EEG-fMRI for Localisation of Focal Epilepsy in Children

Published inPloS one, vol. 11, no. 2, e0149048
Publication date2016

BACKGROUND: Early surgical intervention in children with drug resistant epilepsy has benefits but requires using tolerable and minimally invasive tests. EEG-fMRI studies have demonstrated good sensitivity for the localization of epileptic focus but a poor yield although the reasons for this have not been systematically addressed. While adults EEG-fMRI studies are performed in the "resting state"; children are commonly sedated however, this has associated risks and potential confounds. In this study, we assessed the impact of the following factors on the tolerability and results of EEG-fMRI in children: viewing a movie inside the scanner; movement; occurrence of interictal epileptiform discharges (IED); scan duration and design efficiency. This work's motivation is to optimize EEG-fMRI parameters to make this test widely available to paediatric population. METHODS: Forty-six children with focal epilepsy and 20 controls (6-18) underwent EEG-fMRI. For two 10 minutes sessions subjects were told to lie still with eyes closed, as it is classically performed in adult studies ("rest sessions"), for another two sessions, subjects watched a child friendly stimulation i.e. movie ("movie sessions"). IED were mapped with EEG-fMRI for each session and across sessions. The resulting maps were classified as concordant/discordant with the presumed epileptogenic focus for each subject. FINDINGS: Movement increased with scan duration, but the movie reduced movement by ~40% when played within the first 20 minutes. There was no effect of movie on the occurrence of IED, nor in the concordance of the test. Ability of EEG-fMRI to map the epileptogenic region was similar for the 20 and 40 minute scan durations. Design efficiency was predictive of concordance. CONCLUSIONS: A child friendly natural stimulus improves the tolerability of EEG-fMRI and reduces in-scanner movement without having an effect on IED occurrence and quality of EEG-fMRI maps. This allowed us to scan children as young as 6 and obtain localising information without sedation. Our data suggest that ~20 minutes is the optimal length of scanning for EEG-fMRI studies in children with frequent IED. The efficiency of the fMRI design derived from spontaneous IED generation is an important factor for producing concordant results.

  • Adolescent
  • Attention
  • Brain Mapping/methods
  • Case-Control Studies
  • Child
  • Electroencephalography
  • Epilepsies, Partial/diagnosis/physiopathology
  • Female
  • Humans
  • Immobilization
  • Magnetic Resonance Imaging
  • Male
  • Movement
  • Photic Stimulation
  • Quality Improvement
  • Swiss National Science Foundation - 141165
Citation (ISO format)
CENTENO, Maria et al. Optimising EEG-fMRI for Localisation of Focal Epilepsy in Children. In: PloS one, 2016, vol. 11, n° 2, p. e0149048. doi: 10.1371/journal.pone.0149048
Main files (1)
Article (Published version)
ISSN of the journal1932-6203

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