Epileptogénesis y corteza piriforme: entendiendo a la epilepsia del lóbulo temporal más allá del hipocampo / Epileptogenesis and the piriform cortex: understanding temporal lobe epilepsy beyond the hippocampus

Introducción: Con la experiencia de los registros electroencefalográficos invasivos y el fracaso quirúrgico después de la cirugía, se ha hecho evidente que la epilepsia del lóbulo temporal es mucho más compleja de lo que se creía, y en la actualidad es considerada una enfermedad de redes anatomofuncionales y no de lesiones estructurales. Contenido: La información neurofisiológica e imagenológica actual permite concluir que en esta epilepsia están involucradas varias redes neuronales temporales y extratemporales que contribuyen a la extensión de la zona epileptógena. Una forma de entender el concepto de red epiléptica en la epilepsia del lóbulo temporal es a partir del conocimiento de la corteza piriforme. Varios estudios clínicos han mostrado que en pacientes con epilepsia del lóbulo temporal asociada a esclerosis hipocampal existe una disfunción interictal del procesamiento olfatorio que es más significativa, en comparación con pacientes con epilepsia focal extrahipocampal y controles sanos. Esta alteración es, probablemente, la consecuencia de una red neuronal disfuncional que se extiende más allá del hipocampo y que afecta a otras estructuras cercanas, incluida la corteza piriforme. Conclusión: En este artículo llevamos a cabo una revisión narrativa de la literatura con el objetivo de establecer un vínculo entre la corteza piriforme y la epileptogénesis del lóbulo temporal, y demostramos que esta enfermedad es la consecuencia de una disfunción de redes neuronales que no depende exclusivamente de una anormalidad estructural en el hipocampo o en estructuras cercanas.

Introduction: With the experience of invasive EEG recordings and surgical failure after surgery, it has become clear that temporal lobe epilepsy is much more complex than previously thought, and currently, is conceptualized as a disease of anatomical networks instead of structural lesions. Content: The current neurophysiological and imaging information allows us to conclude that several temporal and extratemporal anatomical networks are involved in this type of epilepsy. One way of understanding the concept of the epileptic network in temporal lobe epilepsy is from the knowledge of the piriform cortex. Several clinical studies have shown that in patients with temporal lobe epilepsy associated with hippocampal sclerosis exists an interictal dysfunction of olfactory processing that is more significant compared to patients with focal extra-hippocampal epilepsy and healthy controls. This alteration is probably the consequence of a dysfunctional neural network that extends beyond the hippocampus and affects other nearby structures, including the piriform cortex. Conclusion: In this article, we carry out a narrative review of the literature with the aim of establishing a link between the piriform cortex and temporal lobe epileptogenesis, demonstrating that this disease is the consequence of a dysfunctional network that does not depend exclusively of a hippocampal structural abnormality.

A research on epilepsy source localization from scalp electroencephalograph based on patient-specific head model and multi-dipole model / 生物医学工程学杂志

Accurate source localization of the epileptogenic zone (EZ) is the primary condition of surgical removal of EZ. The traditional localization results based on three-dimensional ball model or standard head model may cause errors. This study intended to localize the EZ by using the patient-specific head model and multi-dipole algorithms using spikes during sleep. Then the current density distribution on the cortex was computed and used to construct the phase transfer entropy functional connectivity network between different brain areas to obtain the localization of EZ. The experiment result showed that our improved methods could reach the accuracy of 89.27% and the number of implanted electrodes could be reduced by (19.34 ± 7.15)%. This work can not only improve the accuracy of EZ localization, but also reduce the additional injury and potential risk caused by preoperative examination and surgical operation, and provide a more intuitive and effective reference for neurosurgeons to make surgical plans.

Localization of epileptogenic zone based on reconstruction of dynamical epileptic network and virtual resection / 生物医学工程学杂志

Drug-refractory epilepsy (DRE) may be treated by surgical intervention. Intracranial EEG has been widely used to localize the epileptogenic zone (EZ). Most studies of epileptic network focus on the features of EZ nodes, such as centrality and degrees. It is difficult to apply those features to the treatment of individual patients. In this study, we proposed a spatial neighbor expansion approach for EZ localization based on a neural computational model and epileptic network reconstruction. The virtual resection method was also used to validate the effectiveness of our approach. The electrocorticography (ECoG) data from 11 patients with DRE were analyzed in this study. Both interictal data and surgical resection regions were used. The results showed that the rate of consistency between the localized regions and the surgical resections in patients with good outcomes was higher than that in patients with poor outcomes. The average deviation distance of the localized region for patients with good outcomes and poor outcomes were 15 mm and 36 mm, respectively. Outcome prediction showed that the patients with poor outcomes could be improved when the brain regions localized by the proposed approach were treated. This study provides a quantitative analysis tool for patient-specific measures for potential surgical treatment of epilepsy.

Effect of intracerebroventricular injection of miRNA-22 on expression of P2X7 receptor and inflam-matory factors in hippocampus of rats with epilepsy / 中华行为医学与脑科学杂志

Objective To investigate the effect of microRNA-22 (miRNA-22) on the expression of P2X7 receptor and inflammatory factors in hippocampus of rats with epilepsy. Methods Healthy SD male rats were intraperitoneal injected with lithium chloride and pilocarpine to induce epilepsy. Three days later, 45 epileptic rats were randomly divided into three groups: epilepsy group( EP group), miRNA-22 agomir group (EF+agomir group) and miRNA-22 agomir control group ( EF+agomir control group). Another 15 healthy rats were selected as control group(N group). The expression of P2X7 protein was detected by West- ern blot and the levels of miRNA-22, P2X7 mRNA, NF-κB mRNA ,IL-1β mRNA were detected by qRT-PCR. Nissl staining was used to observe the damage of Nissl bodies. Results Western blot result showed that compared with the N group(0. 91±0. 10), the level of P2X7 protein in EP group (1. 17±0. 052) in-creased, and the difference was statistically significant (t=-4. 11,P=0. 02). Compared with the EP+ag-omir control group(0. 94± 0. 14),the expression of P2X7 protein in EP+agomir group (0. 66± 0. 06) de-creased and the difference was significant (t=-3. 10,P=0. 04). And the qRT-PCR results showed that compared with N group, the levels of P2X7mRNA (9. 08±0. 94), NF-κB mRNA (20. 10±2. 15) and IL-1β mRNA (50. 64±5. 42) in EP group increased(t=-14. 96,P<0. 05; t=-15. 38,P<0. 05; t=-15. 87,P<0. 05). The expression of P2X7mRNA (1. 31 ± 0. 64), NF-κB mRNA ( 2. 28 ± 1. 10) and IL-1β mRNA (2. 12±1. 20) in EF+agomir group decreased compared with EP group((9. 08± 0. 94),( 20. 10± 2. 15), (50. 64±5. 42)) and EF+agomir control group((7. 03 ±1. 90),(18. 72±1. 76),(47. 39±6. 16)), and the differences were statistically significant(F=29. 77, P<0. 01;F=98. 99, P<0. 05;F=96. 29, P<0. 01). Nissl staining results showed that a large number of morphologically abnormal and disintegrated Nissl bodies could be observed in the hippocampal CA1 and CA3 regions of EP group,which showed a smaller size,irreg-ular morphology,chromatin pyknosis,boundary blur between nucleus and cytoplasm. Compared with the nor-mal group, the difference was significant (P<0. 05). While in miRNA-22 agomir group, the disintegration of Nissl bodies was improved and the number of Nissl bodies increased. Conclusion Intraventricular injec-tion of miRNA-22 agomir can down-regulate the expression of P2X7 receptor and related inflammatory factors in hippocampus of epileptic rats, thus inhibiting seizures.

Application of positron emission computed tomography /magnetic resonance imaging coregistration in improving epileptic foci detection rate of structural intractable epilepsy in children / 中华实用儿科临床杂志

Objective To study the predictive value of magnetic resonance imaging (MRI),positron emission computed tomography (PET)and PET/MRI coregistration in intractable epilepsy of children.Methods A retrospec-tively analysis was performed based on the surgery data at the Department of Children Epilepsy Center of Peking Univer-sity First Hospital from September 2015 to March 2016.The clinical data,surgery and follow－up study data,interictal and ictal electroencephalogram,MRI,PET and PET/MRI coregistration data were collected.By comparison with the epi-leptogenic zone designed by pre－surgical workup,the accuracy of MRI,PET and PET/MRI coregistration in detecting lesion was assessed.In the patients who had no seizure during≥1 year follow－up,their sensitivity,specificity,positive predictive value,negative predictive value of MRI,PET and PET/MRI coregistration were calculated.Results (1)A total of 62 patients underwent surgery,30 boys and 32 girls. The average age on epilepsy onset was 2. 50 years (2 days－11.70 years),and average age on surgery was 5.10 years old(0.75－15.60 years old).(2)Surgical treat-ment of 62 cases included the resection of the focal or lobar (32 cases,51.6%),and the multilobar (16 cases, 25. 8%).Hemispherotomy was done in 14 cases (22.6%).During ≥1 year follow－up,seizure outcome was Engel class Ⅰ in 57 cases (91.9%)out of the 62 patients,Engel classⅡto Engel classⅣin 1 case,3 cases,and 1 case, respectively.(3)Referred to epileptogenic zone designed by presurgical workup,MRI represented 64.5%(40/62 ca-ses)results with accordance,PET and PET/MRI coregistration was 72.5%(45/62 cases)and 85.5%(53/62 cases), respectively,and the difference was significant(χ2＝7.25,P＝0.03).(4)Based on the patients of Engel class Ⅰ, their sensitivity and specificity were 66.7%,60.0% in MRI,75.4%,60.0% in PET %,and 85.9%,80.0% in PET/MRI coregistration,respectively.(5)There were 11 ＂non－lesion＂ cases of all focal cortical dysplasia in patholo-gy,and subtle structural abnormalities were de tected in 9 cases by reviewing MRI.Conclusions PET/MRI coregistra-tion can improve lesion detection of intractable epilepsy in children.

Verification of dipole fit source localization in patients with epilepsy using postoperative MRI

@#Objective: Dipole fit source (DFS) localisation is a non-invasive imaging process used to identify the epileptogenic zone (EZ) in the brain. The purpose of the present study was to verify the use of DFS localisation for identifying the EZ in patients with and without lesions using magnetic resonance imaging (MRI). Methods: In this study, DFS localisation was used in 16 patients, of whom 7 had no lesions and 9 had lesions on MRI post-surgery, with at least 3 years of follow-up data. For DFS localisation, different scalp electroencephalogram (EEG) ictal activity was assessed (ictal spikes, rhythmic, paroxysmal fast, and obscured activity). DFSs were superimposed with postoperative MRIs to confirm the accuracy of the determined EZs. Results: The DFS correctly identified EZ localization within the resection area in 14 of the 16 patients. These 14 patients were all seizure free after surgery. The two remaining patients, in whom the DFS was adjacent to the resected area, had a decreased seizure frequency following surgery.Conclusions: DFSs determined during preoperative evaluations can provide information on EZ lateralisation and localisation and contribute to the presurgical decision process. Thus, the accurate identification of EZ boundaries is important and can be achieved more reliably with the use of multiple quantitative EEG analysis methods.

The combination application of intracranial buried electrode and cortical electrical stimulation in the excision of the epileptogenic zone in the central zone / 中国神经精神疾病杂志

Objective To investigate the combination application of the intracranial buried electrode and electrical stimulation techniques in excising the epileptogenic zone in the central zone.Methods Seven patients with epileptogenic zone located close to or in the central zone of brain were recruited in the present study.The lone term ECoG monitoring and electrical stimulation of the codex were performed to identify the epileptogenic zone and the central zone of the brain after patients received intracranial electrode implants.The epileptogenic zone was excised with maximum preservation of the cen-tral zone.The patients were follow-up for 6 to 12 months,the outcomes were evaluated based on the Engel's scale and the Karnofsky(KPS)score.Results Seven patients did not experience any seizures and their Engei's and KPS scores were markedly improve after operation.Conclusions Intracranial buried electrodes and cortical electrical stimulation can guide the resection of epileptogenic zone in the central zone.Patients have no seizure and no serious dysfunction after operation and their quality of life was improved markedly.

Comparison of Magnetic Resonance Imaging, Invasive Electroencephalography and Pathologic Findings with Surgical Outcome in Intractable Epilepsy Due to Cortical Dysplasia

BACKGROUND: Intractable partial epilepsy is the most frequent manifestation in cortical dysplasia (CD). The surgical removal of the epileptogenic focus in CD is the main therapeutic option for achieving seizure control. However, it is dif-ficult to predict surgical outcome by current diagnostic methods. We investigated 35 subjects with intractable epilepsy due to CD, in order to know the relationship the extent of lesion in a magnetic resonance imaging (MRI), the epilepto-genic foci in invasive electroencephalography (IEEG), pathologic grading, and surgical outcome. METHODS: We reviewed clinical findings (the seizure history, MRI), IEEG findings (interictal and ictal EEG), pathologic findings and surgical outcomes retrospectively and compared them. All the patients ranged in age from 2 to 45 years (mean: 21.8+10.8years). The time of their seizure onset ranged from 6 months to 31 years (mean:9.4+6.6years). The postopera-tive follow-up period ranged from 7 to 45months (mean:26+14months). RESULTS: Regarding MRI findings, the lesions were focal (within one lobe) in 10, diffuse (more than one lobe) in 7, and no abnormalities in 18 subjects. The ictal onset zones of ictal IEEG had one focus in 18, two in 7, three in 7, and four in 3 subjects. The area of focus was focal in 15, regional in 14, lobar in 4, and in diffuse areas in 2 subjects. Pathologic grading revealed mild in 18, moderate in 5, and severe changes in 13 subjects. Their surgical outcomes were: Engel's class I in 20, class II in 7, class III in 6, and class IV in 2 subjects. The relationships among clinical features, IEEG, regarding pathology and surgical outcomes, revealed that severe pathologic grading had a significant correlation with earlier ictal onset zones (p=0.003), and diffuse MRI lesions. Diffuse ictal onset zones had poor surgical outcomes (p<0.010). CONCLUSIONS: Cortical dysplasia may have a diverse pattern of epileptogenic foci in MRI and IEEG. The earlier the seizure onset is, the severe pathologic grading becomes. When the lesions in MRI as well as the ictal onet zones in IEEG were diffuse, the surgical outcome was poor.

Role of intracranial electrode EEG monitoring for localizing epileptogenic zone in epilepsy / 临床神经病学杂志

Objective To explore the role of intracranial electrode EEG monitoring for localizing epileptogenic zone in epilepsy.Methods 20 patients with refractory temporal lobe epilepsy,whose seizure onsets were unable to be localized by MRI、routine EEG and clinical characteristic,accepted long-term intracranial electrode EEG monitoring.Bitemporal lobe subdural implanted trip electrode were used to perform the ictal and interictal EEG monitoring under the guiding of the stereotactic technique.The results routine of EEG,MRI and intracranial electrode EEG were combined.The accuracy for localization of epilepitogenic zone was evaluated based on the followed-up.Results The intracranial electrode EEG monitoring was implanted within 1～5 d.Each patient was recorded the ictal and interictal discharge and was detected clinical onsets at least twice.All patients could be localized by ictal EEG.The consistency between interical EEG and ictal EEG were observated in 15 cases,the inconsistency in 3 cases,and 2 cases were bilateral discharge in interictal.The clinical outcome showed that patients were seizure-free in 13 cases(65%),improved significantly in 3 cases(15%),improved in 3 cases(15%),unimproved in 1 case(5%)according to Engel's criteria after surgery.No significant complication was found in all patients.Conclusion The intracranial electrode EEG monitoring can localize epileptogenic zone and offer reliable evidence for epilepsy surgery.