IMAGING CORTICAL AND SUBCORTICAL NETWORKS IN HUMAN TEMPORAL LOBE SEIZURES
Abstract number :
3.179
Submission category :
Year :
2002
Submission ID :
3583
Source :
www.aesnet.org
Presentation date :
12/7/2002 12:00:00 AM
Published date :
Dec 1, 2002, 06:00 AM
Authors :
Hal Blumenfeld, Susan Vanderhill, LeBron Paige, Maria Corsi, Edward J. Novotny, Jr., I. George Zubal, Susan S. Spencer. Neurology, Yale University School of Medicine, New Haven, CT; Neurobiology, Yale University School of Medicine, New Haven, CT; Diagnost
RATIONALE: The major behavioral manifestations of temporal lobe seizures include decreased responsiveness, contralateral dystonia, and amnesia. Previous studies have suggested that the dystonia and amnesia, respectively, may be caused by involvement of the basal ganglia and temporal lobe structures during seizures. Based on single photon computed tomography (SPECT) perfusion imaging of individual patients during seizures, we have recently hypothesized that impaired consciousness may be related to seizure spread to the upper brainstem and diencephalic activating systems. Studies on individual patients are subject to noise and inter-subject variability. Here, we use Statistical Parametric Mapping (SPM99) to examine cortical and subcortical activity in a homogenous group of patients during temporal lobe seizures to locate areas which lie outside of expected variation of local brain function.
METHODS: Patients had mesial temporal onset confirmed by convergent diagnostic studies, as well as by pathological demonstration of hippocampal sclerosis, and seizure free outcome for one year after surgery. We analyzed 11 seizures in 10 patients injected with Tc-99m HMPAO from 60-90s after seizure onset, representing the middle to late portion of the seizures. A paired t-test model was used in SPM99 comparing ictal and interictal SPECT scans for the group with an extent threshold of 125 voxels (=1cc) and a height threshold p of 0.01 (Z-score[gt]2).
RESULTS: Voxel clusters demonstrating significant increases in ictal CBF were found in the temporal lobe, ventral basal ganglia, medial thalamus, and upper brainstem. Significant decreases were present in the frontal and parietal association cortex.
CONCLUSIONS: The network of anatomical regions showing increased and decreased activity during temporal lobe seizures may explain ictal behavioral phenomena. Significant increases in activity in the medial thalamus and upper brainstem, may disrupt the normal activation of the cerebral cortex, resulting in decreased activity in the fronto-parietal association cortex, and consequently, in loss of consciousness during temporal lobe seizures.
[Supported by: Dana Foundation.]