Normalization of periictal bihemispheric cerebral perfusion in temporal lobe epilepsy

Epileptic Seizure Detection and Prediction Based on Continuous Cerebral Blood Flow Monitoring – a Review

“…However, techniques and algorithms related to CBF and CBF-based early detection and prediction of seizure onset are not available in the literature. Under normal circumstances, CBF in the two hemispheres is closely correlated under uniform vasomotor control; therefore, any stimulus that increases CBF causes bilateral CBF increase [12][13][14][15][16][17]. However, in the case of partial epilepsy, such as temporal lobe epilepsy, there is a regional CBF (rCBF) abnormality associated with the epileptogenic focus where cerebral perfusion between the two temporal lobes becomes inversely correlated during the inter-ictal and post-ictal periods [13][14][15][16][17].…”

“…Under normal circumstances, CBF in the two hemispheres is closely correlated under uniform vasomotor control; therefore, any stimulus that increases CBF causes bilateral CBF increase [12][13][14][15][16][17]. However, in the case of partial epilepsy, such as temporal lobe epilepsy, there is a regional CBF (rCBF) abnormality associated with the epileptogenic focus where cerebral perfusion between the two temporal lobes becomes inversely correlated during the inter-ictal and post-ictal periods [13][14][15][16][17]. Studies using long-term combined temporal lobe thermal diffusion flowmetry (TDF) and EEG showed that cerebral perfusion in the non-epileptic temporal lobe increases as the perfusion in the contralateral epileptic region decreases during these periods [13][14][15][16][17].…”

“…However, in the case of partial epilepsy, such as temporal lobe epilepsy, there is a regional CBF (rCBF) abnormality associated with the epileptogenic focus where cerebral perfusion between the two temporal lobes becomes inversely correlated during the inter-ictal and post-ictal periods [13][14][15][16][17]. Studies using long-term combined temporal lobe thermal diffusion flowmetry (TDF) and EEG showed that cerebral perfusion in the non-epileptic temporal lobe increases as the perfusion in the contralateral epileptic region decreases during these periods [13][14][15][16][17]. Normalization of the cerebral perfusion in these regions was observed during a 10 minute peri-ictal period [17].…”

“…Studies using long-term combined temporal lobe thermal diffusion flowmetry (TDF) and EEG showed that cerebral perfusion in the non-epileptic temporal lobe increases as the perfusion in the contralateral epileptic region decreases during these periods [13][14][15][16][17]. Normalization of the cerebral perfusion in these regions was observed during a 10 minute peri-ictal period [17].…”

“…Finally, to estimate the steady state response, a measure of the thermal conductivity, Valvano et al [45] measured the applied heating power, P(t), and determined through linear regression the steady state response using the following correlation [35]: (17) where I is the coefficient of steady state response that depends on the thermal conductivity of the medium, and S is the coefficient of transient response (slope) that depends on the thermal diffusivity of the medium [35,46]. Figure 5 shows such transient response of a TDF probe submerged/embedded in glycerol, tissue and agar-gelled water, respectively, to determine I and S [45].…”