Cerebral Hemodynamic Evaluation of Main Cerebral Vessels in Epileptic Patients Based on Transcranial Doppler

Objective: To study whether there is a difference in peak and mean blood flow velocity between the left and right major cerebral vessels in patients with epilepsy.Methods: Sixteen patients with epilepsy underwent FDG18-PET-CT (PET) scan and electroencephalogram (EEG) examinations. Transcranial Doppler (TCD) was used to detect the peak flow velocity (PFV), mean flow velocity (MFV), and other hemodynamic indicators of bilateral anterior, middle, and posterior cerebral arteries in each patient. According to different patterns of the PET or interictal EEG, the differences in PFV, and MFV of corresponding vessels on both sides under different patterns were compared.Results: According to the PET of the low-metabolism region corresponding to the supplying artery, the PFV and MFV of the supplying artery in the low-metabolism region were lower than the value of the corresponding contralateral vessel. The PFV and MFV on the low metabolic side of PET were lower than that of the corresponding vessels on the opposite side. The PFV and MFV on the discharge side of interictal EEG were also lower than the PFV and MFV of the corresponding vessels on the opposite side. The MFV of posterior cerebral artery on the low metabolic side of PET or the interictal discharge side was significantly different from that of the contralateral vessels (P < 0.05). However, the other aforementioned differences in PFV and MFV did not achieve statistical significance.Conclusion: In epileptic patients, the PFV and MFV of main cerebral vessels on the PET hypometabolized side or the interictal discharge side was lower than that of corresponding vessels on the contralateral side. To some extent, the difference in the MFV of PCA between the bilateral sides can facilitate the lateral diagnosis of the epileptogenic zone.

Region-specific effects of early-life status epilepticus on the adult hippocampal CA3 – medial entorhinal cortex circuitry in vitro: focus on interictal spikes and concurrent high-frequency oscillations

ABSTRACTConvulsive status epilepticus (SE) in immature life is often associated with lasting neurobiological changes. We provoked SE by pentylenetetrazole in postnatal day 20 rat pups and examined communication modalities between the temporal hippocampus and medial entorhinal cortex (mEC) in vitro. After a minimum of 40 days post-SE, we prepared combined temporal hippocampal - medial entorhinal cortex (mEC) slices from conditioned (SE) and naïve (N) adult rats and recorded 4-aminopyridine-induced spontaneous epileptiform interictal-like discharges (IED) simultaneously from CA3 and mEC layer V-VI. We analyzed IED frequency and high frequency oscillations (HFOs) in intact slices and after surgical separation of hippocampus from mEC, by two successive incisions (Schaffer collateral cut, Parasubiculum cut). In all slices, IED frequency was higher in CA3 vs mEC and Raster plots indicated no temporal coincidence between them either in intact or in CA1-cut slices. IED frequency was significantly higher in SE mEC, but similar in SE and N CA3, independently of connectivity state. Ripples (R) and Fast Ripples (FR) coincided with IEDs and their power differed between SE and N intact slices, both in CA3 and mEC. CA3 FR/R ratios were higher in the absence of mEC. Moreover, SE (vs N) slices showed significantly higher FR/R ratios independently of the presence of mEC. Taken together, these findings suggest lasting effects of immature SE in network dynamics governing hippocampal-entorhinal communication which may impact adult cognitive, behavioral and/or seizure threshold sequalae.HIGHLIGHTSEarly-life Status Epilepticus (SE) impacts on the adult hippocampal – entorhinal communication in the in vitro 4-AP modelPost-SE CA3 output decreases in HFO power with no change in interictal discharge frequencyPost-SE mEC output increases both in HFO power and interictal discharge frequencyInterictal HFO dynamics in CA3-mEC change upon the connectivity state of the two areas and priorhistory of early-life SE

Factors affecting interictal unilateral and bilateral discharges and ictal diffusion patterns of scalp electroencephalogram in temporal lobe epilepsy

Purpose To evaluate preoperative factors influencing unilateral and bilateral interictal discharges in TLE, and ictal diffusion patterns in scalp EEG during onset of the seizure.Methods This was a retrospective analysis of 129 patients with TLE who had undergone surgery; cases were classified into two groups of unilateral and bilateral discharge groups according to interictal discharge patterns in the EEG. In this study, unilateral interictal discharges meaned that the discharge was confined to one hemisphere, while bilateral interictal discharges meaned that the discharge involved both hemispheres. Differences between the two groups in age, gender, duration of disease, frequency of seizures, MRI findings, origin of TLE, antiepileptic drug administration, and ictal diffusion patterns during seizures were statistically analyzed. In addition, the differences in ictal diffusion patterns between left and right TLE were statistically analyzed.Results There were a total of 74 cases of unilateral discharges, including unilateral discharges in the temporal region, anterior head including both temporal and frontal regions, and unilateral hemispheric discharges, and there were another 55 cases of bilateral discharges, including bilateral temporal area, bilateral anterior heads, and bilateral hemispheric multi-brain areas. There were 60 cases of left TLE and 69 cases of right TLE. There were no statistically significant differences in gender, duration of disease, frequency of seizures, MRI manifestations, administration of antiepileptic drugs, and ictal diffusion patterns between interictal unilateral and bilateral discharge groups, but, there were statistically significant differences in age and side of origin of the TLE. Scalp EEG recorded 11 different ictal diffusion pattern types, and the difference in terms of whether the EEG recorded the diffusion pattern to be confined to the same hemisphere or spread to both hemispheres was statistically significant between the left and right temporal lobes.Conclusion Age and side of origin of TLE affects the TLE interictal discharge patterns. Older patients are more prone to bilateral discharges. Bilateral discharges are more common in right TLE, and the onset of EEG more likely to bilateral diffusion in right TLE.

Pre-Operative Interictal Discharge Patterns and Magnetic Resonance Imaging Findings Affect Prognosis of Temporal Lobe Epilepsy Surgery

Objective: This study investigated whether pre-operative interictal discharge patterns detected by electroencephalogram (EEG) and magnetic resonance imaging (MRI) findings affect the surgical prognosis in temporal lobe epilepsy (TLE) patients. Methods: A retrospective analysis of 115 cases of patients with refractory TLE was carried out from October 2010 to 2014 based on the classification of pre-operative interictal discharge patterns in EEG and MRI findings. The patients were followed up for 4 years after surgery. The ILAE method was used to assess differences in seizure-free rate among different types of interictal discharge pattern as well as in MRI findings. Results: A total of 115 cases were classified according to interictal discharge patterns in EEG, including normal cases, unilateral anterior discharge, unilateral multi-region discharge, and bilateral discharge. MRI findings were classified into negative results and positive results. Unilateral anterior and bilateral discharges showed statistically significant differences in post-operative seizure-free rates (p< 0.001). MRI-positive cases showed good overall post-operative outcome, irrespective of interictal discharge pattern in the EEG, whereas MRI-negative cases showed good overall prognosis if the interictal discharge pattern in EEG occurred in the unilateral anterior region. Conclusion: If the pre-operative interictal discharge pattern in EEG is confined to the unilateral anterior region, prognosis is good. If there are abnormalities in MRI findings, post-operative prognosis is good, regardless of pre-operative interictal discharge patterns in EEG. Surgical intervention is highly recommended for TLE patients with normal MRI findings and interictal discharge confined to the unilateral anterior region.