title: The Relevance of Interictal Bold Changes to Lateralize Seizure Focus Using Simultaneous EEG-fMRI.
abstract: OBJECTIVE
  The main challenge in assessing patients with epilepsy is the localization of neuronal networks involved in seizure generation and the lateralization of seizure onset. Electro encephalogram-functional magnetic resonance imaging (EEG-fMRI) is a noninvasive multimodal imaging technique for epilepsies where the data is acquired based on the interictal epileptiform discharges (IED). Since this is a new technique, the specificity for lateralizing epileptic focus is yet to be established. The peak blood oxygen level dependent (BOLD) signal in an interictal recording is known to correlate with seizure onset focus. In this study we are proposing a simple and practical method without the need for high end post processing techniques of fmri data. The peak BOLD signal derived from EEG-fMRI aids to lateralise seizure focus in a given cerebral lobe (region of interest, ROI). This is a very useful tool in a clinical setting on a given individual clinical case, when other modalities may be conflicting or inconclusive.
  
  
  METHODS
  We analyzed simultaneous EEG-fMRI of 10 different types of refractory epilepsy. The lateralization index was calculated from the statistical significant clusters obtained between the different ROI and results were validated with other modalities.
  
  
  RESULTS
  Lateralization of seizure focus corroborated well in temporal and extratemporal lobe epilepsy, reflex epilepsy and lesional epilepsy. The only drawback of EEG-fMRI in our study was if insignificant BOLD changes were associated with the given IED.
  
  
  CONCLUSIONS
  EEG-fMRI can be helpful additional tool in the pre-surgical work-up of refractory epilepsy particularly when lateralization with other modalities is conflicting or inconclusive.
authors.affiliation: Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences, Bangalore Karnataka, India.
authors.forename: Sandhya
authors.initials: S
authors.lastname: Mangalore
authors.affiliation: Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences, Bangalore Karnataka, India.
authors.forename: Rose Dawn
authors.initials: RD
authors.lastname: Bharath
authors.affiliation: Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences, Bangalore Karnataka, India.
authors.forename: Neeraj
authors.initials: N
authors.lastname: Upadhyay
authors.affiliation: Neurology, National Institute of Mental Health and Neurosciences, Bangalore Karnataka, India.
authors.forename: Ganne
authors.initials: G
authors.lastname: Chaitanya
authors.affiliation: Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences, Bangalore Karnataka, India.
authors.forename: Rajanikanth
authors.initials: R
authors.lastname: Panda
authors.affiliation: Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences, Bangalore Karnataka, India.
authors.forename: A K
authors.initials: AK
authors.lastname: Gupta
authors.affiliation: Neurology, National Institute of Mental Health and Neurosciences, Bangalore Karnataka, India.
authors.forename: P Satish
authors.initials: PS
authors.lastname: Chandra
authors.affiliation: Neurosurgery, National Institute of Mental Health and Neurosciences, Bangalore Karnataka, India.
authors.forename: Malla Bhaskar
authors.initials: MB
authors.lastname: Rao
authors.affiliation: Neuropathology, National Institute of Mental Health and Neurosciences, Bangalore Karnataka, India.
authors.forename: Anita
authors.initials: A
authors.lastname: Mahadevan
keywords: EEG fMRI; Interictal discharges; Lateralise; Refractory epilepsy; Seizure focus
references.citation: Brain. 1999 Sep;122 ( Pt 9):1679-88
references.pmid: 10468507
references.citation: Brain. 2011 Oct;134(Pt 10):2867-86
references.pmid: 21752790
references.citation: Magn Reson Imaging. 2008 Jun;26(5):594-601
references.pmid: 18158224
references.citation: Neurol Med Chir (Tokyo). 2006 Oct;46(10 ):518-21
references.pmid: 17062994
references.citation: Epilepsia. 2006 Aug;47(8):1308-19
references.pmid: 16922875
references.citation: Brain. 2001 Jun;124(Pt 6):1218-27
references.pmid: 11353737
references.citation: Ann Neurol. 2008 Jul;64(1):35-41
references.pmid: 18570291
references.citation: Clin Neurophysiol. 2001 Apr;112(4):713-9
references.pmid: 11275545
references.citation: Neuroimage. 2001 Sep;14(3):780-7
references.pmid: 11506550
references.citation: J Neurol Neurosurg Psychiatry. 2010 Aug;81(8):922-7
references.pmid: 20547617
references.citation: Neuroimage. 2000 Aug;12(2):230-9
references.pmid: 10913328
references.citation: Neurology. 1999 Mar 10;52(4):798-809
references.pmid: 10078731
references.citation: Neurology. 1999 Mar 23;52(5):1038-43
references.pmid: 10102425
references.citation: Neuroimage. 2009 Oct 1;47(4):1532-44
references.pmid: 19505583
references.citation: Epilepsia. 2004 Jan;45(1):85-9
references.pmid: 14692913
references.citation: Neuroimage. 1998 Oct;8(3):229-39
references.pmid: 9758737
references.citation: Epilepsy Behav. 2003 Dec;4(6):776-80
references.pmid: 14698719
references.citation: Cereb Cortex. 2000 May;10(5):512-28
references.pmid: 10847601
references.citation: Epilepsia. 2003 Oct;44(10):1328-39
references.pmid: 14510827
references.citation: Ann Neurol. 2006 May;59(5):835-42
references.pmid: 16634031
references.citation: Brain Res. 2006 May 9;1088(1):148-66
references.pmid: 16678803