Three-dimensional localization of abnormal EEG activity in migraine: a low resolution electromagnetic tomography (LORETA) study of migraine patients in the pain-free interval.
Investigating the brain of migraine patients in the pain-free interval may shed light on the basic cerebral abnormality of migraine, in other words, the liability of the brain to generate migraine attacks from time to time. Twenty unmedicated "migraine without aura" patients and a matched group of healthy controls were investigated in this explorative study. 19-channel EEG was recorded against the linked ears reference and was on-line digitized. 60 x 2-s epochs of eyes-closed, waking-relaxed activity were subjected to spectral analysis and a source localization method, low resolution electromagnetic tomography (LORETA). Absolute power was computed for 19 electrodes and four frequency bands (delta: 1.5-3.5 Hz, theta: 4.0-7.5 Hz, alpha: 8.0-12.5 Hz, beta: 13.0-25.0 Hz). LORETA "activity" (=current source density, ampers/meters squared) was computed for 2394 voxels and the above specified frequency bands. Group comparison was carried out for the specified quantitative EEG variables. Activity in the two groups was compared on a voxel-by-voxel basis for each frequency band. Statistically significant (uncorrected P < 0.01) group differences were projected to cortical anatomy. Spectral findings: there was a tendency for more alpha power in the migraine that in the control group in all but two (F4, C3) derivations. However, statistically significant (P < 0.01, Bonferroni-corrected) spectral difference was only found in the right occipital region. The main LORETA-finding was that voxels with P < 0.01 differences were crowded in anatomically contiguous cortical areas. Increased alpha activity was found in a cortical area including part of the precuneus, and the posterior part of the middle temporal gyrus in the right hemisphere. Decreased alpha activity was found bilaterally in medial parts of the frontal cortex including the anterior cingulate and the superior and medial frontal gyri. Neither spectral analysis, nor LORETA revealed statistically significant differences in the delta, theta, and beta bands. LORETA revealed the anatomical distribution of the cortical sources (generators) of the EEG abnormalities in migraine. The findings characterize the state of the cerebral cortex in the pain-free interval and might be suitable for planning forthcoming investigations.
Clemens
Béla
B
Department of Neurology, Kenézy Hospital, Bartók Béla út 3, 4031, Debrecen, Hungary. clemensdr@freemail.hu
Bánk
József
J
Piros
Pálma
P
Bessenyei
Mónika
M
Veto
Sára
S
Tóth
Márton
M
Kondákor
István
I
D000293:Adolescent; D000328:Adult; D000513:Alpha Rhythm; D001921:Brain / Q000473:pathology / Q000503:physiopathology; D001931:Brain Mapping / Q000379:methods; D002540:Cerebral Cortex / Q000473:pathology / Q000503:physiopathology*; D003627:Data Interpretation, Statistical; D004569:Electroencephalography; D055590:Electromagnetic Phenomena; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000503:physiopathology*; D020326:Migraine without Aura / Q000503:physiopathology; D010296:Parietal Lobe / Q000473:pathology / Q000503:physiopathology; D013702:Temporal Lobe / Q000473:pathology / Q000503:physiopathology; D013997:Time Factors; D014054:Tomography / Q000379:methods*