Premium
BOLD responses related to focal spikes and widespread bilateral synchronous discharges generated in the frontal lobe
Author(s) -
An Dongmei,
Dubeau François,
Gotman Jean
Publication year - 2015
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/epi.12909
Subject(s) - supplementary motor area , frontal lobe , ictal , electroencephalography , psychology , dorsolateral prefrontal cortex , thalamus , neuroscience , haemodynamic response , prefrontal cortex , magnetic resonance imaging , hemodynamics , functional magnetic resonance imaging , operculum (bryozoa) , medicine , cardiology , radiology , biology , heart rate , blood pressure , cognition , botany , genus
Summary Objective To investigate whether specific frontal regions have a tendency to generate widespread bilateral synchronous discharges ( WBSD s) and others focal spikes and to determine the regions most involved when WBSD s occur; to assess the relationships between the extent of electroencephalography ( EEG ) discharges and the extent of metabolic changes measured by EEG /functional magnetic resonance imaging ( fMRI ). Methods Thirty‐seven patients with interictal epileptic discharges ( IED s) with frontocentral predominance underwent EEG / fMRI . Patients were divided into a Focal (20 patients) group with focal frontal spikes and a WBSD group (17 patients). Maps of hemodynamic responses related to IED s were compared between the two groups. Results The mean number ± SD of IED s in the Focal group was 137.5 ± 38.1 and in the WBSD group, 73.5 ± 16.6 (p = 0.07). The volume of hemodynamic responses in the WBSD group was significantly larger than in the Focal group (mean, 243.3 ± 41.1 versus 114.8 ± 27.4 cm 3 , p = 0.01). Maximum hemodynamic responses occurred in both groups in the following regions: dorsolateral prefrontal, mesial prefrontal, cingulate, and supplementary motor cortices. Maxima in premotor and motor cortex, frontal operculum, frontopolar, and orbitofrontal regions were found only in the Focal group, and maxima in thalamus and caudate only occurred in the WBSD group. Thalamic responses were significantly more common in the WBSD group (14/17) than in the Focal group (7/20), p = 0.004. Deactivation in the default mode network was significantly more common in the WBSD group (14/17) than in the Focal group (10/20), p = 0.04. Significance The spatial distribution and extent of blood oxygen level–dependent ( BOLD ) responses correlate well with electrophysiologic changes. Focal frontal spikes and WBSD s are not region specific in the frontal lobe, and the same frontal region can generate focal and generalized discharges. This suggests that widespread discharges reflect widespread epileptogenicity rather than a focal discharge located in a region favorable to spreading. The thalamus plays an important role in bilateral synchronization.