Temporal lobe spiking reveals distinct patterns of fMRI activation with intracranial EEG-fMRI
Poster No:
2327
Submission Type:
Abstract Submission
Authors:
Antis George1, William Wilson1, Daniel Pittman1, Perry Dykens1, Laura Gill2, Joseph Peedicail1, Ismael Gaxiola-Valdez1, Bradley Goodyear1, Paolo Federico1, Victoria Mosher1, Craig Beers1
Institutions:
1University of Calgary, Calgary, Alberta, 2Univeristy of Calgary, Calgary, Alberta
First Author:
Co-Author(s):
Introduction:
Temporal lobe epilepsy (TLE) is the most common focal epilepsy in adults (Téllez-Zenteno et al., 2012) . TLE has a high probability of becoming medically refractory and is frequently considered for surgical intervention. However, 30% of TLE cases have non-lesional magnetic resonance imaging (MRI) results, which has been associated with worse surgical outcomes, prompting the need for novel imaging techniques (Kim et al., 2016). Simultaneous intracranial electroencephalography-functional MRI (iEEG-fMRI) can measure the hemodynamic changes associated with interictal epileptiform discharges (IEDs) recorded directly from the brain. This study was designed to characterize the fMRI activation associated with IEDs recorded exclusively from the mesial temporal lobes of patients with non-lesional TLE.
Methods:
Nineteen MRI-negative patients undergoing iEEG monitoring with mesial temporal IEDs were studied using simultaneous iEEG-fMRI at 3Tesla. IEDs were marked and statistically significant clusters of BOLD activation were identified (Z-score 2.3, p value <0.05). The anatomical locations corresponding to the fMRI activation for each patient were determined and patients were grouped based on location and pattern of fMRI activity.
Results:
Two patterns of fMRI activation associated with mesial temporal IEDs emerged: primarily localized (n =8), where activation was primarily located within the ipsilateral temporal lobe, and primarily diffuse (n = 11), where widespread extratemporal activation was detected. The primarily diffuse group reported significantly fewer focal to bilateral tonic-clonic seizures.
· Figure 1. IED-associated fMRI activation patterns.
Conclusions:
Simultaneous iEEG-fMRI can measure the hemodynamic changes associated with focal IEDs not visible on scalp EEG, such as those arising from the mesial temporal lobe. Significant fMRI activation associated with these IEDs was observed in all patients. Half of the patients had brain activation primarily localized to the ipsilateral temporal lobe, and half showed widespread activation in several extratemporal structures. Those patients with fewer focal to bilateral tonic-clonic seizures also exhibited widespread IED-associated fMRI activations, which may suggest a neuroprotective mechanism limiting the spread of ictal events.
Modeling and Analysis Methods:
EEG/MEG Modeling and Analysis 2
Novel Imaging Acquisition Methods:
BOLD fMRI 1
Physiology, Metabolism and Neurotransmission :
Neurophysiology of Imaging Signals
Keywords:
Electroencephaolography (EEG)
ELECTROPHYSIOLOGY
Epilepsy
FUNCTIONAL MRI
1|2Indicates the priority used for review
Provide references using author date format
Téllez-Zenteno J.F. (2012), 'A review of the epidemiology of temporal lobe epilepsy', Epilepsy research and treatment.