Imaging onset and propagation of ECT-induced seizures.
OBJECTIVE
Regions of seizure onset and propagation in human generalized tonic-clonic seizures are not well understood. Cerebral blood flow (CBF) measurements with single photon emission computed tomography (SPECT) during electroconvulsive therapy (ECT)-induced seizures provide a unique opportunity to investigate seizure onset and propagation under controlled conditions.


METHODS
ECT stimulation induces a typical generalized tonic-clonic seizure, resembling spontaneous generalized seizures in both clinical and electroencephalogram (EEG) manifestations. Patients were divided into two groups based on timing of ictal (during seizure) SPECT tracer injections: 0 s after ECT stimulation (early group), and 30 s after ECT (late group). Statistical parametric mapping (SPM) was used to determine regions of significant CBF changes between ictal and interictal scans on a voxel-by-voxel basis.


RESULTS
In the early injection group, we saw increases near the regions of the bitemporal stimulating electrodes as well as some thalamic and basal ganglia activation. With late injections, we observed increases mainly in the parietal and occipital lobes, regions that were quiescent 30 s prior. Significant decreases occurred only at the later injection time, and these were localized to the bilateral cingulate gyrus and left dorsolateral frontal cortex.


CONCLUSIONS
Activations in distinct regions at the two time points, as well as sparing of intermediary brain structures, suggest that ECT-induced seizures propagate from the site of initiation to other specific brain regions. Further work will be needed to determine if this propagation occurs through cortical-cortical or cortico-thalamo-cortical networks. A better understanding of seizure propagation mechanisms may lead to improved treatments aimed at preventing seizure generalization.
Enev
Miro
M
Departments of Neurology, Yale University School of Medicine, New Haven, Connecticut 06520-8018, USA.
McNally
Kelly A
KA
Varghese
George
G
Zubal
I George
IG
Ostroff
Robert B
RB
Blumenfeld
Hal
H
D001931:Brain Mapping; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D003866:Depressive Disorder / Q000628:therapy; D003865:Major Depressive Disorder / Q000628:therapy; D004558:Electric Stimulation / Q000379:methods; D004565:Electroconvulsive Therapy / Q000379:methods*; D004569:Electroencephalography / Q000706:statistics & numerical data; D004829:Epilepsy, Generalized / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D004830:Epilepsy, Tonic-Clonic / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data; D019690:Technetium Tc 99m Exametazime; D013788:Thalamus / Q000000981:diagnostic imaging / Q000503:physiopathology; D015899:Tomography, Emission-Computed, Single-Photon / Q000706:statistics & numerical data
D019690:Technetium Tc 99m Exametazime