Analisys of the hemodynamic responses in patients with temporal lobe epilepsy by using simultaneous acquisitions of electroencephalography and functional magnetic resonance imaging

Author(s)

Brunno Machado de Campos

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas
• Defense date: 2013-02-15

Examining board members

Fernando Cendes; Edson Amaro Júnior; Gabriela Castellano

• Advisor: Fernando Cendes

Abstract

Introduction: The multimodal technique of electroencephalography (EEG) coupled to functional magnetic resonance imaging (fMRI) presents additional physical characteristics. This method allows not only evaluating physiological neural activities, but also the dynamics of neuropathologies as epilepsy. Within the group of epilepsy, temporal lobe epilepsy (TLE) is particularly important due to its high prevalence and morbidity. Objective: To investigate and compare the patterns of hemodynamic changes associated with interictal epileptiform discharges (IEDs) in patients with TLE with (TLE-HS) or without (TLE-NL) signs of hippocampal sclerosis in MRI, through the combined use of EEG and fMRI techniques (EEG-fMRI). Methods: Twenty five patients diagnosed with TLE underwent EEG-fMRI scans, 12 with TLE-NL and 13 TLE-HS. MR images were acquired on a 3T scanner and EEG recorded with 64 electrodes compatible with MRI. The time for IED was used to assess the BOLD positive (BOLDpos) and negative (BOLDneg) responses. Analysis of EEG-fMRI MRI structural analyses were performed with SPM8-VBM8 software. The functional analyses were performed with the peak of the hemodynamic response function (HRF) in 0 second (early) and 5 seconds (late) after IED. Results: The BOLDpos maps in TLE-HS group showed early hemodynamic changes in ipsilateral temporal lobe, contralateral insula and precentral gyrus and late hemodynamic changes in ipsilateral putamen, bilateral anterior cingulate, insula and temporal lobes. In TLE-NL, diffuse early BOLDpos was observed, with the most significant changes in the ipsilateral medial frontal gyrus, while late BOLDpos was observed in the ipsilateral insula and superior temporal gyrus. In both groups the structural analysis showed significant reduction of gray matter in areas that extend beyond the temporal lobe, but with no significant overlap with areas of BOLDpos. In both groups of patients BOLDneg was observed in areas consistent with default mode network (DMN). Interpretation: The functional networks related to the IED differ in TLE-HS and TLE-NL. The regions with the most significant gray matter atrophy do not coincide with these functional networks. There is possible suppression of activity in the DMN areas related to IED in TLE patients with or without signs of HS (AU)

• FAPESP's process: 11/03477-7 - Analysis of hemodynamic response in patients with mesial temporal lobe epilepsy using electroencephalography and functional magnetic resonance
• Grantee: Brunno Machado de Campos
• Support Opportunities: Scholarships in Brazil - Master