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Temporal and Extratemporal BOLD Responses to Temporal Lobe Interictal Spikes
Author(s) -
Kobayashi Eliane,
Bagshaw Andrew P.,
Bénar ChristianGeorge,
Aghakhani Yahya,
Andermann Frederick,
Dubeau François,
Gotman Jean
Publication year - 2006
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/j.1528-1167.2006.00427.x
Subject(s) - ictal , temporal lobe , electroencephalography , scalp , epilepsy , artifact (error) , stereoelectroencephalography , neuroscience , lobe , magnetic resonance imaging , psychology , medicine , nuclear medicine , anatomy , radiology
Summary: Purpose: Simultaneous EEG and functional MRI ( f MRI) allows measuring metabolic changes related to interictal spikes. Our objective was to investigate blood oxygenation level–dependent (BOLD) responses to temporal lobe (TL) spikes by using EEG‐ f MRI recording. Methods: We studied 35 patients who had a diagnosis of temporal lobe epilepsy (TLE) and active TL spiking on routine scalp EEG recording. Two‐hour sessions of continuous EEG‐ f MRI were recorded, and spikes were identified after offline artifact removal and used as events in the f MRI analysis. Each type of spike was analyzed separately, as one EEG‐ f MRI study. We determined significant (p < 0.05) positive (activation) and negative (deactivation) BOLD responses for each study. Results: Twenty‐seven patients had spikes during scanning (19 unilateral and eight bilateral). From a total of 35 f MRI studies, 29 (83%) showed BOLD responses: 14 had both activations and deactivations; 12, activations only; and three, deactivations only. Six (17%) showed no responses. Nineteen studies had mainly neocortical TL activation: Sixteen (84%) of 19 concordant with spikes, 12 of 16 with concomitant activation of the contralateral TL, and 16 of 19 with additional extratemporal activation; few showed exclusively mesial TL activation. Seventeen studies showed deactivation, either extratemporal plus temporal (n = 8) or exclusively extratemporal (n = 9). Conclusions: BOLD responses to TL spikes occurred in 83% of studies, predominated in the spiking temporal lobe, and manifested as activation or deactivation. Responses often involved the contralateral homologous cortex at the time of unilateral spikes and were frequently observed in extratemporal regions, suggesting that TL epileptic spikes can affect neuronal activity at a distance through synaptic connections.