Positive and Negative Network Correlations in Temporal Lobe Epilepsy

Abstract

Temporal lobe seizures are accompanied by complex behavioral phenomena including loss of consciousness, dystonic movements and neuroendocrine changes. These phenomena may arise from extended neural networks beyond the temporal lobe. To investigate this, we imaged cerebral blood flow (CBF) changes during human temporal lobe seizures with single photon emission computed tomography (SPECT) while performing continuous video/EEG monitoring. We found that temporal lobe seizures associated with loss of consciousness produced CBF increases in the temporal lobe, followed by increases in bilateral midline subcortical structures. These changes were accompanied by marked bilateral CBF decreases in the frontal and parietal association cortex. In contrast, temporal lobe seizures in which consciousness was spared were not accompanied by these widespread CBF changes. The CBF decreases in frontal and parietal association cortex were strongly correlated with increases in midline structures such as the mediodorsal thalamus. These results suggest that impaired consciousness in temporal lobe seizures may result from focal abnormal activity in temporal and subcortical networks linked to widespread impaired function of the association cortex.

Functional neuroanatomy of disorders of consciousness

“…In line with their clinical condition, patients with MCS show a partial preservation of this large-scale associative frontoparietal network [22]. Similar findings of frontoparietal deactivation have been recorded in somnambulism as well as in absence and complex partial (mainly in the temporal lobe) seizures [6][7][8], whereas temporal lobe seizures without loss of consciousness are not accompanied by these widespread changes [7].…”

“…On the one hand, during vivid dreams, wakefulness is lowered, whereas internal awareness is preserved. On the other hand, in some pathological states, wakefulness is spared, while awareness is impaired [6][7][8]. These states comprise the minimally conscious state (MCS) and the vegetative state (VS, now also called the unresponsive wakefulness syndrome -UWS [9,10]), as well as absence seizures, complex partial seizures, and somnambulism (Fig.…”

Brain SPECT in mesial temporal lobe epilepsy: comparison between visual analysis and SPM

“…The two false positive studies seen in the SPM(ictal) analysis were considered true positive in this analysis, since the perfusion in the epileptogenic focus was compared among the ictal and interictal studies, and not among lobe hemispheres in the same study. DISCUSSION SPM has been already performed in the TLE patients 7,8,12,16 . We previously studied a group of MTLE using SPM 16 and did not find significant areas of hypoperfusion in the interictal SPECT images.…”

“…The majority of studies using SPM SPECT in epilepsy compare the entire patient population to the control group [6][7][8] , while a few studies compare SPM SPECT of each patient to the control group. SPM sensitivity in ictal SPECT, in all these studies, ranges from 50% 6 to 89% 9 .…”

Longitudinal variations of brain functional connectivity: A case report study based on a mouse model of epilepsy

“…As such, studies based on FC are highly valuable for addressing disruptions of brain functioning in neurological disorders such as epilepsy, a major neurological disorder characterized by chronic unprovoked seizures. Indeed, FC studies in epilepsy are abundant 2– 7 , but these studies typically perform group comparisons between health and disease; as an alternative to this approach, we present a longitudinal FC analysis on the same mouse brain across different days.…”