Temporal and Extratemporal BOLD Responses to Temporal Lobe Interictal Spikes

• Published in: Epilepsia (Copenhagen) Vol. 47; no. 2; pp. 343 - 354
• Main Authors: Kobayashi, Eliane, Bagshaw, Andrew P., Bénar, Christian‐George, Aghakhani, Yahya, Andermann, Frederick, Dubeau, François, Gotman, Jean
• Format: Journal Article
• Language: English
• Published: 350 Main Street , Malden , MA 02148 , USA and 9600 Garsington Road , Oxford , OX4 2XG , England Blackwell Publishing Inc 01-02-2006; Blackwell
• Subjects: Adult; Anticonvulsants. Antiepileptics. Antiparkinson agents; Biological and medical sciences; BOLD response; Brain Mapping; EEG‐fMRI; Electroencephalography - statistics & numerical data; Epilepsy, Temporal Lobe - blood; Epilepsy, Temporal Lobe - diagnosis; Epilepsy, Temporal Lobe - physiopathology; Female; Functional Laterality - physiology; Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy; Humans; Image Processing, Computer-Assisted; Interictal temporal lobe spikes; Investigative techniques, diagnostic techniques (general aspects); Magnetic Resonance Imaging - statistics & numerical data; Male; Medical sciences; Neocortex - physiopathology; Nervous system; Nervous system (semeiology, syndromes); Neural Pathways - physiology; Neural Pathways - physiopathology; Neurology; Neuropharmacology; Oxygen - blood; Pharmacology. Drug treatments; Prospective Studies; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Temporal Lobe - physiopathology; TLE; Spike; Temporal lobe; EEG-fMRI-TLE-Interictal temporal lobe spikes- BOLD response; Nervous system diseases; Epilepsy; Central nervous system disease; Electrophysiology; Electroencephalography; Nuclear magnetic resonance imaging; Cerebral disorder
• ISSN: 0013-9580; 1528-1167
• DOI: 10.1111/j.1528-1167.2006.00427.x

Purpose: Simultaneous EEG and functional MRI (fMRI) 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‐fMRI 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‐fMRI were recorded, and spikes were identified after offline artifact removal and used as events in the fMRI analysis. Each type of spike was analyzed separately, as one EEG‐fMRI 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 fMRI 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.