Cerebral blood flow and temporal lobe epileptogenicity

Abstract

<jats:p>Long-term surface cerebral blood flow (CBF) monitoring was performed to test the hypothesis that temporal lobe epileptogenicity is a function of epileptic cortical perfusion. Forty-three bitemporal 2-hour periictal CBF studies were performed in 13 patients. Homotopic regions of temporal cortex maintained interictal epileptic cortical hypoperfusion and nonepileptic normal cortical CBF. At 10 minutes preictus, a statistically significant, sustained increase in CBF was detected on the epileptic temporal lobe. Two minutes preictus, there was approximation of CBF in the epileptic and nonepileptic temporal lobes. Thereafter, electrocorticographic (ECoG) and clinical seizure onset occurred. The linear relationship between CBF in the two hemispheres (epileptic and nonepileptic) was the inverse of normal (y = -0.347x + 62.767, r = 0.470, df = 95, p &lt; 0.05). The data indicated a direct linear correlation between epileptic cortical CBF and seizure interval (frequency-1), a clinical measure of epileptogenicity (r = 0.610, df = 49, p &lt; 0.05). Epileptogenicity was also found to be a logarithmic function of the difference between nonepileptic and epileptic cortical perfusion (r = 0.564, df = 58, t = 5.20, p &lt; 0.05). The results showed that progressive hypoperfusion of the epileptic focus correlated with a decreased seizure interval (increased epileptogenicity). Increased perfusion of the epileptic focus correlated with an increased seizure interval (decreased epileptogenicity). The fact that CBF alterations precede ECoG seizure activity suggests that vasomotor changes may produce electrical and clinical seizure onset.</jats:p>

Effect of Endogenous Estrogen on Blood Flow Through Carotid Arteries

“…This can play a role in the pathogenesis of menstrual cycle-related epilepsy and migraine, as it has been shown that these clinical events may be triggered by a slight reduction of flow within certain regions of the brain. [43][44][45][46][47] In summary, we have demonstrated that fluctuations of endogenous estrogen across the menstrual cycle are associated with substantial changes in blood flow volume in the ICA. Mainly decreased vascular resistance within the brain causes the estrogen-related promotion of flow.…”

Characterization of the hemodynamic modes associated with interictal epileptic activity using a deformable model‐based analysis of combined EEG and functional MRI recordings

“…Indeed, several studies in patients have shown that the hemodynamic responses are highly variable and slower for negative than for positive BOLD signals [Bagshaw et al, 2004;Benar et al, 2002]. Also, long-lasting hemodynamic changes have been shown to occur several minutes prior to seizures [Baumgartner et al, 1998;Federico et al, 2005;Makiranta et al, 2005;Weinand et al, 1997]. In this context, HRFs modeling early BOLD changes occurring before IEDs are non-causal because they precede IEDs, used as input to the linear system [Hawco et al, 2007;Moeller et al, 2008].…”

Patterns of Cortical Oxygen Saturation Changes During CO 2 Reactivity Testing in the Vicinity of Cerebral Arteriovenous Malformations

“…Patients with chronic seizures may have altered vasoreactivity because abnormalities in rCBF/metabolism and morphological capillary alterations in resected tissue may occur. 16,17 These findings, however, are confined to the epileptogenic focus. Highly sensitive MRI sequences, PET or single photon emission CT, and EEG define those patients with structural, metabolic, and electrophysiological abnormalities extending into the lateral cortex, which will then undergo a temporal lobe resection instead of selective AH.…”