Identification of Seizure Onset Zone from Intracranial EEG Using Source Selection-Based Domain Adaptation.

For focal epilepsy patients, correctly identifying the seizure onset zone (SOZ) is essential for surgical treatment. In automated realistic SOZ identification, it is necessary to identify the SOZ of an unknown patient using another patient's electroencephalogram (EEG). However, in such cases, the influence of individual differences in EEG becomes a bottleneck. In this paper, we propose the method with domain adaptation and source patient selection to address the issue of individual differences in EEG and improve performance. The proposed method was evaluated on intracranial EEG data from 11 patients with epilepsy caused by focal cortical dysplasia. The results showed that the proposed method significantly improved SOZ identification performance compared to existing methods without domain adaptation and source patient selection. In addition, it was suggested that data from residual-seizure patients may have adversely affected estimation performance. Visualization of the prediction on MRI images showed that the proposed method might detect SOZs missed by epileptologists.

Seizure onset zone identification using phase-amplitude coupling and multiple machine learning approaches for interictal electrocorticogram.

Automatic seizure onset zone (SOZ) localization using interictal electrocorticogram (ECoG) improves the diagnosis and treatment of patients with medically refractory epilepsy. This study aimed to investigate the characteristics of phase-amplitude coupling (PAC) extracted from interictal ECoG and the feasibility of PAC serving as a promising biomarker for SOZ identification. We employed the mean vector length modulation index approach on the 20-s ECoG window to calculate PAC features between low-frequency rhythms (0.5-24 Hz) and high frequency oscillations (HFOs) (80-560 Hz). We used statistical measures to test the significant difference in PAC between the SOZ and non-seizure onset zone (NSOZ). To overcome the drawback of handcraft feature engineering, we established novel machine learning models to learn automatically the characteristics of the obtained PAC features and classify them to identify the SOZ. Besides, to handle imbalanced dataset classification, we introduced novel feature-wise/class-wise re-weighting strategies in conjunction with classifiers. In addition, we proposed a time-series nest cross-validation to provide more accurate and unbiased evaluations for this model. Seven patients with focal cortical dysplasia were included in this study. The experiment results not only showed that a significant coupling at band pairs of slow waves and HFOs exists in the SOZ when compared with the NSOZ, but also indicated the effectiveness of the PAC features and the proposed models in achieving better classification performance .

Effect of vagus nerve stimulation against generalized seizure and status epilepticus recurrence.

Objective: Vagus nerve stimulation (VNS) is a palliative surgery for drug-resistant epilepsy. The two objectives of this study were to (1) determine the seizure type most responsive to VNS and (2) investigate the preventive effect on status epilepticus (SE) recurrence. Methods: We retrospectively reviewed 136 patients with drug-resistant epilepsy who underwent VNS implantation. We examined seizure outcomes at 6, 12, and 24 months following implantation of VNS as well as at the last visit to the Juntendo Epilepsy Center. Univariate analysis and multivariate logistic regression models were used to estimate the prognostic factors. Results: 125 patients were followed up for at least 1 year after VNS implantation. The percentage of patients with at least a 50% reduction in seizure frequency compared with prior to VNS implantation increased over time at 6, 12, and 24 months after VNS implantation: 28, 41, and 52%, respectively. Regarding overall seizure outcomes, 70 (56%) patients responded to VNS. Of the 40 patients with a history of SE prior to VNS implantation, 27 (67%) showed no recurrence of SE. The duration of epilepsy, history of SE prior to VNS implantation and seizure type were correlated with seizure outcomes after VNS implantation in univariate analysis (p = 0.05, p < 0.01, and p = 0.03, respectively). In multivariate logistic regression analysis, generalized seizure was associated with VNS response [odds ratio (OR): 4.18, 95% CI: 1.13-15.5, p = 0.03]. A history of SE prior to VNS implantation was associated with VNS non-responders [(OR): 0.221, 95% CI: 0.097-0.503, p < 0.01]. The duration of epilepsy, focal to bilateral tonic-clonic seizure and epileptic spasms were not significantly associated with VNS responders (p = 0.07, p = 0.71, and p = 0.11, respectively). Conclusion: Following 125 patients with drug-resistant epilepsy for an average of 69 months, 56% showed at least 50% reduction in seizure frequency after VNS implantation. This study suggests that generalized seizure is the most responsive to VNS, and that VNS may reduce the risk of recurrence of SE. VNS was shown to be effective against generalized seizure and also may potentially influence the risk of further events of SE, two marker of disease treatment that can lead to improved quality of life.

An integrated genetic analysis of epileptogenic brain malformed lesions.

Focal cortical dysplasia is the most common malformation during cortical development, sometimes excised by epilepsy surgery and often caused by somatic variants of the mTOR pathway genes. In this study, we performed a genetic analysis of epileptogenic brain malformed lesions from 64 patients with focal cortical dysplasia, hemimegalencephy, brain tumors, or hippocampal sclerosis. Targeted sequencing, whole-exome sequencing, and single nucleotide polymorphism microarray detected four germline and 35 somatic variants, comprising three copy number variants and 36 single nucleotide variants and indels in 37 patients. One of the somatic variants in focal cortical dysplasia type IIB was an in-frame deletion in MTOR, in which only gain-of-function missense variants have been reported. In focal cortical dysplasia type I, somatic variants of MAP2K1 and PTPN11 involved in the RAS/MAPK pathway were detected. The in-frame deletions of MTOR and MAP2K1 in this study resulted in the activation of the mTOR pathway in transiently transfected cells. In addition, the PTPN11 missense variant tended to elongate activation of the mTOR or RAS/MAPK pathway, depending on culture conditions. We demonstrate that epileptogenic brain malformed lesions except for focal cortical dysplasia type II arose from somatic variants of diverse genes but were eventually linked to the mTOR pathway.

Proper Therapy Selection Improves Epilepsy Outcomes in Patients With Multilobar Sturge-Weber Syndrome.

BACKGROUND: Hemispherectomy is an optimal treatment for patients with Sturge-Weber syndrome (SWS) affecting the whole hemisphere; however, a consensus has not been reached regarding therapeutic choices for those with involvement of two to three lobes. In this study, we compared seizure and cognitive outcomes between medical and surgical treatment groups in patients with multilobar involvement. METHODS: We evaluated 50 patients with multilobar involvement. Surgical indications included (1) antiepileptic drug (AED)-resistant seizures; (2) developmental delay; and (3) cortical atrophy. Twenty-nine patients were classified in the medical treatment group (MTG), and 21 patients were in the surgical treatment group (STG). Seizure type and frequency, SWS electroencephalography score (SWS-EEGS), and pretherapeutic and posttherapeutic SWS neurological scores (SWS-NS) were compared between groups. Median ages at the initial evaluation of the MTG and STG were 4 and 2 years, and at the final evaluation were 13 and 17 years, respectively. RESULTS: The STG had a higher incidence (76.2%) of focal to bilateral tonic-clonic seizures and status epilepticus, although no difference in SWS-EEGS. Seizure and cognitive subcategories of SWS-NS at initial evaluation were worse in the STG (P = 0.025 and P = 0.007). The seizure subcategory in MTG and STG improved after therapy (P = 0.002 and P = 0.001). Cognition was maintained in MTG and improved in STG (P = 0.002). The seizure-free rates in MTG and STG were 58.6% and 85.7%, respectively. CONCLUSIONS: Appropriate therapeutic choices improved seizure outcomes. Although patients who required surgery had more severe epilepsy and cognitive impairment, surgery improved both.

Epilepsy surgery without lipoma removal for temporal lobe epilepsy associated with lipoma in the Sylvian fissure.

Epileptic seizure is the common symptom associated with lipomas in the Sylvian fissure (Sylvian lipomas). Removal of these lipomas carries risks of hemorrhage and brain damage. We report a surgical strategy of not removing the lipoma in a case of intractable temporal lobe epilepsy associated with Sylvian lipoma. We performed anterior temporal lobectomy with preservation of the pia mater of the Sylvian fissure and achieved seizure freedom. Focal cortical dysplasia type 1 of the epileptic neocortex adjacent to the Sylvian lipoma was pathologically diagnosed. We recommend our surgical procedure in similar cases to avoid complications and achieve adequate seizure control.

[Surgical Site Infections in Hydrocephalus Surgery and Pediatric Neurosurgery].

Hydrocephalus surgery is one of the most frequently performed procedures in pediatric neurosurgery. The incidence of surgical site infections during this surgery is high. This complication has not improved with the evolution of neurosurgical procedures. This may be due to immature immune system and skin barrier function of children compared to adults and the fact that hydrocephalus surgery involves placement of an alien surgical device in the body. To overcome this issue, it is important to follow procedures that have been validated as beneficial for the prevention of infection in literature. Therefore, in this article, we present our current understanding of infectious complications of hydrocephalus surgery, including shunt device surgery in adults and non-hydrocephalus pediatric neurosurgery, and provide recommendations for minimizing infectious complications and strategies to prevent infections in these surgeries.

[Reactivation of latent viruses in Neurology].

After establishing latent infection, some viruses can be reactivated by the alteration of host immunological conditions. First, we reviewed viruses that can cause neuronal damage by reactivation. Then we focused on the herpes simplex virus (HSV). The reactivation leads to neuronal damages through two possible mechanisms; "reactivation of a latent herpes virus" by which viruses can cause direct virus neurotoxicity, and "post-infectious immune inflammatory response" by which a focal reactivation of HSV leads to an inflammatory reaction. The former is radiologically characterized by cortical lesions, the latter is characterized by subcortical white matter lesions. We experienced a female, who underwent the right posterior quadrantectomy and then developed recurrent herpes encephalitis caused by herpes simplex reactivation, which pathologically demonstrated inflammation in the white matter, suggesting a post-infectious immune inflammatory response. The patient was successfully treated with immunosuppressants. The reactivation of the HSV is extremely rare in Japan. Neurologists should recognize this condition because this disorder will increase as epilepsy surgery gains more popularity.

Impact of COVID-19 pandemic on epilepsy care in Japan: A national-level multicenter retrospective cohort study.

OBJECTIVE: The impact of the coronavirus disease 2019 (COVID-19) pandemic on epilepsy care across Japan was investigated by conducting a multicenter retrospective cohort study. METHODS: This study included monthly data on the frequency of (1) visits by outpatients with epilepsy, (2) outpatient electroencephalography (EEG) studies, (3) telemedicine for epilepsy, (4) admissions for epilepsy, (5) EEG monitoring, and (6) epilepsy surgery in epilepsy centers and clinics across Japan between January 2019 and December 2020. We defined the primary outcome as epilepsy-center-specific monthly data divided by the 12-month average in 2019 for each facility. We determined whether the COVID-19 pandemic-related factors (such as year [2019 or 2020], COVID-19 cases in each prefecture in the previous month, and the state of emergency) were independently associated with these outcomes. RESULTS: In 2020, the frequency of outpatient EEG studies (-10.7%, p<0.001) and cases with telemedicine (+2,608%, p=0.031) were affected. The number of COVID-19 cases was an independent associated factor for epilepsy admission (-3.75*10-3 % per case, p<0.001) and EEG monitoring (-3.81*10-3 % per case, p = 0.004). Further, the state of emergency was an independent factor associated with outpatient with epilepsy (-11.9%, p<0.001), outpatient EEG (-32.3%, p<0.001), telemedicine for epilepsy (+12,915%, p<0.001), epilepsy admissions (-35.3%; p<0.001), EEG monitoring (-24.7%: p<0.001), and epilepsy surgery (-50.3%, p<0.001). SIGNIFICANCE: We demonstrated the significant impact that the COVID-19 pandemic had on epilepsy care. These results support those of previous studies and clarify the effect size of each pandemic-related factor on epilepsy care.

Surgery for intractable epilepsy after severe encephalopathy with reversible splenial lesion and new onset hippocampal lesion associated with parechovirus.

We describe a case of severe encephalopathy with reversible splenial lesion associated with parechovirus, followed by intractable temporal lobe epilepsy (TLE), which was improved by epilepsy surgery. A 3-year-old girl was admitted because of fever, consciousness disturbance and generalized tonic clonic seizure. Her seizure lasted for four hours. Fluid-attenuated inversion recovery (FLAIR) showed a hyperintensity in the splenium of the corpus callosum. Electroencephalogram (EEG) demonstarated continuous diffuse epileptic activity represented by synchronous and rhythmic high-amplitude spikes and waves, which led to the diagnosis of status epilepticus. Her consciousness was improved with fosphenytoin, midazolam and methylprednisolone pulse after 3 days. Seven days later, FLAIR hyperintensity in the splenium of the corpus callosum was disappeared; however, a hyperintensity in the right hippocampus was detected. Since the stool examination was positive for parechovirus, her final diagnosis was reversible splenial lesion syndrome (RESLES) associated with parechovirus. At age 8, she experienced epigastric sensation and consciousness disturbance once a week. Based on the scalp EEG and radiological findings, she was diagnosed with intractable right TLE. We performed a right selective amygdalohippocampectomy and anterior temporal disconnection at 10 years of age. One year and 3 months after surgery, she was seizure free. To our knowledge, this is the first report of severe febrile epilepticus status. with RESLES associated with parechovirus, followed by intractable TLE, which was resolved by epilepsy surgery.

Delineation of the epileptogenic zone by Phase-amplitude coupling in patients with Bottom of Sulcus Dysplasia.

PURPOSE: The removal of the bottom of sulcus dysplasia (BOSD) often includes the gyral crown; however, this method has been controversial. We hypothesized that the epileptogenic zone of the BOSD does not include the gyral crown. To reveal the depth and extent of the epileptogenic zone of the BOSD, we applied the two electrophysiological modalities: (1) the occurrence rate (OR) of high-frequency oscillations (HFOs) and (2) modulation index (MI), reflecting the strength of phase-amplitude coupling between HFOs and slow oscillations. METHODS: We investigated the ripples [80-200 Hz] and fast ripples [200-300 Hz]) in HFOs and MI (HFOs [80-300 Hz] and slow oscillations [3-4 Hz]). We opened the sulcus at the BOSD and implanted the subdural electrodes directly over the MRI visible lesion. All patients (n = 3) underwent lesionectomy and the gyral crown was preserved. RESULTS: Pathological findings demonstrated focal cortical dysplasia type IIb and seizure freedom was achieved. The OR of the HFOs was not significantly different between the BOSD and the gyral crown. In contrast, the MI between HFOs and slow oscillations in the BOSD was significantly higher than that in the gyral crown. CONCLUSION: High MI values distinguished the epileptogenic BOSD from the non-epileptogenic gyral crowns. MI could be a more informative biomarker of epileptogenicity than the OR of HFOs in a subset of patients with the BOSD.

Can intraoperative electrocorticography be used to minimize the extent of resection in patients with temporal lobe epilepsy associated with hippocampal sclerosis?

OBJECTIVE: Tailored surgery to extensively resect epileptogenic lesions using intraoperative electrocorticography (ioECoG) may improve seizure outcomes. However, resection of large areas is associated with decreased memory function postoperatively. The authors assessed whether ioECoG could provide useful information on how to minimize the focus resection and obtain better seizure outcomes without memory deterioration. They examined the postoperative seizure-free period and memory alteration in a retrospective cohort of patients with mesial temporal lobe epilepsy (TLE) due to hippocampal sclerosis (HS) in whom the extent of removal was determined using ioECoG findings. METHODS: The authors enrolled 82 patients with TLE associated with HS who were treated surgically. Transsylvian amygdalohippocampectomy was indicated as the first step. When visual inspection identified interictal epileptic discharges from the lateral temporal lobe on ioECoG, anterior temporal lobectomy (ATL) was eventually performed. The patients were divided into the selective amygdalohippocampectomy (SA, n = 40) and ATL (n = 42) groups. Postoperative seizure outcomes were assessed at 1, 2, 3, 5, and 7 years postoperatively using the International League Against Epilepsy classification. The Kaplan-Meier survival analysis was applied to evaluate the period of seizure recurrence between the SA and ATL groups. Factors attributed to seizure recurrence were analyzed using the Cox proportional hazards model, and they were as follows: epileptic focal laterality; age at seizure onset (< 10 or ≥ 10 years old); seizure frequency (more than weekly or less than weekly seizures); history of focal to bilateral tonic-clonic seizure; infectious etiology; and surgical procedure. The Wechsler Memory Scale-Revised was used to evaluate memory function pre- and postoperatively. RESULTS: Seizure outcomes were significantly worse in the SA group than in the ATL group at 2 years postoperatively (p = 0.045). The International League Against Epilepsy class 1 outcomes at 7 years postoperatively in the SA and ATL groups were 63% and 81%, respectively. Kaplan-Meier analysis showed that seizure recurred significantly earlier in the SA group than in the ATL group (p = 0.031). The 2-way ANOVA analysis was used to compare the SA and ATL groups in each memory category, and revealed that there was no significant difference regardless of the side of surgery. CONCLUSIONS: Visual assessment of ioECoG cannot be used as an indicator to minimize epileptic focus resection in patients with TLE associated with HS. ATL is more effective in obtaining seizure-free outcomes; however, both ATL and SA can preserve memory function.

Seizure Onset Zone Identification Based on Phase-Amplitude Coupling of Interictal Electrocorticogram.

Presurgical localization from interictal electrocorticogram (ECoG) and resection of seizure onset zone (SOZ) are difficult processes to achieve seizure freedom. Recently, high frequency oscillations (HFOs) have been recognized as reliable biomarkers for epilepsy surgery which has a relation with the phase of low frequency activities in ECoG. Considering the recent valid biomarker for epilepsy surgery, we hypothesize that the approach of coupling between HFOs and low frequency phases differs SOZ from non-seizure onset zone (NSOZ). This study proposes phase-amplitude coupling (PAC) method to identify SOZ by measuring whether the amplitude of HFOs is coupled with a phase at 2-34 Hz in ECoG. Besides, three machine learning models for PAC-based features are designed for SOZ detection. Four patients with focal cortical dysplasia (FCD) are examined to observe efficiency. Experimental results indicate that the mode of coupling is a potential feature to detect SOZ.Clinical relevance- This suggests the PAC feature between low frequency phase and HFO amplitude may be used as a candidate biomarker to detect SOZ.

Case Report: Subtotal Hemispherotomy Modulates the Epileptic Spasms in Aicardi Syndrome.

The mechanism of epileptic spasms (ES) in Aicardi syndrome (AS) remains obscure. We compared intraoperative high-frequency oscillations (HFOs) and phase-amplitude coupling (PAC) before and after subtotal hemispherotomy in a 3-month-old girl with drug-resistant ES secondary to AS. Fetal ultrasonography showing corpus callosum agenesis, bilateral ventricular dilatation, and a large choroid plexus cyst confirmed AS diagnosis. Her ES started when she was 1 month old and had ten series of clustered ES per day despite phenobarbital and vitamin B6 treatment. After subtotal hemispherotomy, her ES dramatically improved. We analyzed two intraoperative electrocorticography modalities: (1), occurrence rate (OR) of HFOs; (2), PAC of HFOs and slow wave bands in the frontal, central, and parietal areas. We hypothesized that HFOs and PAC could be the biomarkers for efficacy of subtotal hemispherotomy in AS with ES. PAC in all three areas and OR of HFOs in the frontal and parietal areas significantly decreased, while OR of HFOs in the central area remained unchanged after subtotal hemispherotomy. We have demonstrated the usefulness of evaluating intraoperative HFOs and PAC to assess subtotal hemispherotomy effectiveness in AS patients with ES. Disconnecting the thalamocortical and subcortical pathways in the epileptic network plays a role in controlling ES generation.

Extent of Leptomeningeal Capillary Malformation is Associated With Severity of Epilepsy in Sturge-Weber Syndrome.

BACKGROUND: Individuals with Sturge-Weber syndrome (SWS) often expereince intractable epilepsy and cognitive decline. We hypothesized that the extent of the leptomeningeal capillary malformation (LCM) may correlate with the severity of neurological impairment due to SWS. We tested the hypothesis in a cross-sectional study of seizure severity and electroencephalographic (EEG) findings and a retrospective cohort study for surgical indications related to the extent of the LCM. METHODS: We enrolled 112 patients and classified them according to LCM distribution: (1) bilateral, (2) hemispheric, (3) multilobar, and (4) single lobe. Age at seizure onset, seizure semiology and frequency, and EEG findings were compared. Surgical indications were evaluated for each group by Fisher exact test, and predictors for surgery were evaluated by univariate and multivariate analyses. Therapeutic efficacy was evaluated by the SWS-Neurological Score (SWS-NS). RESULTS: The bilateral and hemispheric groups had early seizure onset (4.0 months old and 3.0 months old), frequent seizures (88.9% and 80.6% had more than one per month), focal-to-bilateral tonic-clonic seizures (88.9% and 74.2%), and status epilepticus (100% and 87.1%). The groups' EEG findings did not differ substantially. Surgical indications were present in 77.8% of the bilateral, 88.1% of the hemispheric, and 46.8% of the multilobar groups. Seizure more than once per month was a predictor of surgical treatment. Seizure subscore improved postoperatively in the hemispheric and multilobar groups. Even after surgical treatment, the bilateral and hemispheric groups exhibited higher SWS-NSs than members of the other groups. CONCLUSION: Our study demonstrated a strong association between extensive LCM and epilepsy severity. Surgical intervention improved seizure outcome in patients with SWS with large LCMs.

Relapse of Herpes Simplex Encephalitis by Epilepsy Surgery 35 Years after the First Infection: A Case Report and Literature Review.

Late relapse of herpes simplex encephalitis (HSE) is defined as the recurrence of HSE more than 3 months after the initial exposure. The postoperative diagnosis of HSE following neurosurgery is complicated because the clinical presentation can mimic other common complications of neurosurgery. Cerebrospinal fluid polymerase chain reactions (CSF-PCR) is the gold standard for the diagnosis of HSE. We describe a case of late HSE relapse after epilepsy surgery in a patient who required a brain biopsy due to repeated negative CSF-PCR results. A 38-year-old woman had a history of HSE from the age of 3 years. She had intractable epilepsy from the age of 20 years and underwent right posterior quadrant disconnection (PQD) at the age of 38 years. Postoperatively, she had a right hemispheric intracerebral hemorrhage (ICH) and her consciousness was gradually worsening. Her consciousness improved after removal of the ICH. However, her consciousness gradually deteriorated again. Fluid-attenuated inversion recovery (FLAIR) revealed bilateral hyperintensity in the frontal lobes, including the white matter. CSF-PCR for herpes simplex virus (HSV) was performed twice, but yielded negative results. We performed a brain biopsy to target FLAIR hyperintensity in the right frontal lobe. PCR of the brain specimen was positive for HSV. Her consciousness improved with acyclovir, methylprednisolone, and cyclophosphamide. To our knowledge, this is a case of HSE induced by epilepsy surgery which had the longest duration until relapse after the initial HSE episode. A brain biopsy can be used to confirm the diagnosis of suspected HSE when CSF-PCR results are negative.

The epileptogenic zone in pharmaco-resistant temporal lobe epilepsy with amygdala enlargement.

Temporal lobe epilepsy with amygdala enlargement (TLE-AE) has been considered a subtype of TLE. We evaluated the epileptogenic zone in patients with TLE-AE, who underwent intracranial video-EEG (ivEEG) and/or intraoperative electrocorticography (ioECoG) as well as epilepsy surgery. Eleven patients with TLE-AE were enrolled and investigated based on seizure profile, volumetric MRI, the Wechsler Memory Scale-Revised (WMS-R), the location of seizure onset zone (SOZ) and irritative zone (IZ) based on ivEEG (n=8), the location of interictal epileptiform discharges (IEDs) based on ioECoG (11), surgical procedure, and seizure outcome. The mean age at seizure onset was 34.9 years (range: 23-57). The mean duration of seizures was 5.0 years (range: 1-10). The number of AEDs was 2.3 (range: 1-5). The mean seizure frequency was nine per month (range: 1-30/month). All patients presented with focal impaired awareness seizures with (n=9) and without (2) secondary generalized convulsions. Volumetric MRI analysis showed unilateral enlarged amygdala with statistical significance (p<0.01). None of the patients' hippocampi had any abnormality based on MRI. Pre-operative mean verbal, visual, and delayed recall scores based on the WMS-R were over 100. The SOZ and IZ were identified in both the amygdala and hippocampus in seven patients and in only the amygdala in one patient based on ivEEG. IEDs were identified in the hippocampus in six patients and in both the amygdala and hippocampus in four patients based on ioECoG. All 11 patients underwent anterior temporal lobectomy, including amygdala resection, with multiple hippocampal transections (dominant hemisphere: seven patients) and resection (non-dominant hemisphere: three patients). Nine (81.8%) of 11 patients achieved seizure freedom with a mean follow-up of 26 months (range: 12-47). Post-operative WMS-R results did not show any significant deterioration, with a mean follow-up of 15 months (range: 12-24). The resected amygdala showed no histopathological abnormality. The epileptogenic zone of TLE-AE involves both the amygdala and hippocampus. ivEEG may be needed to explore the SOZ in normal hippocampus in addition to enlarged amygdala. Amygdala resection and multiple hippocampal transections may control the epileptogenic limbic system and save memory function in patients with TLE-AE.

Strong coupling between slow oscillations and wide fast ripples in children with epileptic spasms: Investigation of modulation index and occurrence rate.

OBJECTIVE: Epileptic spasms (ES) often become drug-resistant. To reveal the electrophysiological difference between children with ES (ES+) and without ES (ES-), we compared the occurrence rate (OR) of high-frequency oscillations (HFOs) and the modulation index (MI) of coupling between slow and fast oscillations. In ES+, we hypothesized that (1) pathological HFOs are more widely distributed and (2) slow oscillations show stronger coupling with pathological HFOs than in ES-. METHODS: We retrospectively reviewed 24 children with drug-resistant multilobar onset epilepsy, who underwent intracranial video electroencephalography prior to multilobar resections. We measured the OR of HFOs and determined the electrodes with a high rate of HFOs by cluster analysis. We calculated MI, which reflects the degree of coupling between HFO (ripple/fast ripple [FR]) amplitude and 5 different frequency bands of delta and theta activities (0.5-1 Hz, 1-2 Hz, 2-3 Hz, 3-4 Hz, 4-8 Hz). RESULTS: In ES+ (n = 10), the OR(FRs) , the number of electrodes with high-rate FRs, and the MI(FRs & 3-4 Hz) in all electrodes were significantly higher than in ES- (n = 14). In both the ES+ and ES- groups, MI(ripples/FRs & 3-4 Hz) was the highest among the 5 frequency bands. Within the good seizure outcome group, the OR(FRs) and the MI(FRs & 3-4 Hz) in the resected area in ES+ were significantly higher than in ES- (OR[FRs] , P = .04; MI[FRs & 3-4 Hz] , P = .04). SIGNIFICANCE: In ES+, the larger number of high-rate FR electrodes indicates more widespread epileptogenicity than in ES-. High values of OR(FRs) and MI(FRs & 3-4 Hz) in ES+ compared to ES- are a signature of the severity of epileptogenicity. We proved that ES+ children who achieved seizure freedom following multilobar resections exhibited strong coupling between slow oscillations and FRs.