Masaki Iwasaki | Tohoku University (original) (raw)
Papers by Masaki Iwasaki
Epilepsia, 2005
Objectively to evaluate whether independent spike detection by human interpreters is clinically v... more Objectively to evaluate whether independent spike detection by human interpreters is clinically valid in magnetoencephalography (MEG) and to characterize detection differences between MEG and scalp electroencephalography (EEG). We simultaneously recorded scalp EEG and MEG data from 43 patients with intractable focal epilepsy. Raw EEG and MEG waveforms were reviewed independently by two experienced epileptologists, one for EEG and one for MEG, blinded to the other modality and to the clinical information. The number and localization of spikes detected by EEG and/or MEG were compared in relation to clinical diagnosis based on postoperative seizure freedom. Interictal spikes were captured in both EEG and MEG in 31, in MEG alone in eight, in EEG alone in one, and in neither modality in three patients. The number of detections ranged widely with no statistical difference between modalities. A median of 25.7% of total spikes was detectable by both modalities. Spike localization was similarly consistent with the epilepsy diagnosis in 85.2% (EEG) and 78.1% (MEG) of the patients. Inaccurate localization occurred only in those cases with very few spikes detected, especially when the detections were in one modality alone. Interictal epileptiform discharges are easily perceived in MEG. Independent spike identification in MEG can provide clinical results comparable, but not superior, to EEG. Many spikes were seen in only one modality or the other; therefore the use of both EEG and MEG may provide additional information.
md?type= text.html Montrouge, 20-04-2019 Masaki Iwasaki You will find below the electronic reprin... more md?type= text.html Montrouge, 20-04-2019 Masaki Iwasaki You will find below the electronic reprint of your article (pdf format): Ictal deafness in drug-resistant MRI-negative epilepsy
Epileptic encephalopathy with electrical status epilepticus during sleep (ESES) is often refracto... more Epileptic encephalopathy with electrical status epilepticus during sleep (ESES) is often refractory to medical treatment and leads to poor cognitive outcomes. Corpus callosotomy may be an effective treatment option for drug-resistant ESES with no focal etiology. We retrospectively identified three patients who underwent corpus callosotomy for drug-resistant ESES in our institution. Electroencephalography (EEG) findings and cognitive functions were evaluated before surgery, at 3 months, 6 months, 1 year, and 2 years after surgery. Age at surgery was 6 years 10 months, 7 years 9 months, and 8 years 4 months, respectively. Period between the diagnosis of ESES and surgery ranged from 7 to 25 months. All patients had no obvious structural abnormalities and presented with cognitive decline despite multiple antiseizure medications and steroid therapies. One patient showed complete resolution of ESES and an improvement of intelligence quotient after surgery. Epileptiform EEG was lateralized to one hemisphere after surgery and spike wave index (SWI) was decreased with moderate improvement in development and seizures in the other 2 patients. SWI re-exacerbated from 6 months after surgery, but without subsequent developmental regression in these 2 patients. Corpus callosotomy may become an important treatment option for drug-resistant ESES in patients with no structural abnormalities.
urgical treatment for patients with drug-resistant focal epilepsy is efficacious in both adults a... more urgical treatment for patients with drug-resistant focal epilepsy is efficacious in both adults and children. 1,2 The primary goal of epilepsy surgery is to control a patient's seizures. Another important goal in pediatric patients is to prevent the cognitive and developmental stagnation or regression induced by persistent epileptic activity. Surgically treatable etiologies, such as hemimegalencephaly and focal cortical dysplasia, can cause severe seizures in infants, complicated by developmental epileptic encephalopathy such as early infantile epileptic encephalopathy or West syndrome. 3 Infants with a large or hemispheric epileptogenic lesion
Objectives: We developed a Markov model to simulate a treatment flow of epilepsy patients who ref... more Objectives: We developed a Markov model to simulate a treatment flow of epilepsy patients who refer to specialized care from non-specialized care, and to surgery from specialized care for estimation of patient distributions and expenditures caused by increasing the referral rate for specialized care. Methods: This budget impact analysis of treatment flow optimization in epilepsy patients was performed as a long-term simulation using the Markov model by comparing the current treatment flow and the optimized treatment flow. In the model, we simulated the prognosis of new onset 5-yearold epilepsy patients (assuming to represent epilepsy occurring between 0 and 10 years of age) treated over a lifetime period. Direct costs of pharmacotherapies, management fees and surgeries are included in the analysis to evaluate the annual budget impact in Japan. Results: In the current treatment flow, the number of refractory patients treated with four drugs by non-specialized care were estimated as 8766 and yielded JPY5.8 billion annually. However, in the optimized treatment flow, the number of patients treated with four drugs by non-specialized care significantly decreased and who continued the monotherapy increased. The costs for the four-drug therapy by non-specialized care were eliminated. Hence cost-saving of JPY9.5 billion (-5% of the current treatment flow) in total national expenditures would be expected. Conclusion: This study highlights that any policy decision-making for referral optimization to specialized care in appropriate epilepsy patients would be feasible with a cost-savings or very few budget impacts. However, important information in the decision-making such as transition probability to the next therapy or excuse for sensitive limitations is not available currently. Therefore, further research with reliable data such as big data analysis or a national survey with real-world treatment patterns is needed.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Epileptic disorders : international epilepsy journal with videotape, Jan 16, 2015
The primary motor cortex of the oro-facial level can be removed without permanent deficits, becau... more The primary motor cortex of the oro-facial level can be removed without permanent deficits, because of the bilateral representation of the innate functions. In contrast, resective surgery of the hand motor cortex or higher levels presents more challenges. We treated two adult patients with intractable epilepsy caused by small focal cortical dysplasia in the pre-central gyrus located between the foot and hand primary motor cortices. Focal cortical resection was guided by cortical EEG and intra-operative motor evoked potential, resulting in seizure freedom without neurological deficits in both cases. These cases illustrate that resective surgery can be safely performed in the primary motor cortex even dorsal to the oro-facial level, as long as the critical regions of the hand and foot motor cortices remain intact. Accurate delineation of the anatomical lesion and functional areas using intra-operative neurophysiological monitoring is crucial for successful outcome of the surgery.
Introduction Interictal MEG dipoles associated with temporal lobe epilepsy (TLE) can be classifie... more Introduction Interictal MEG dipoles associated with temporal lobe epilepsy (TLE) can be classified according to localization and orientation into anterior temporal horizontal (ATH), anterior temporal vertical and posterior temporal vertical (PTV) dipoles [1, 2, 3]. The MEG dipole pattern may be related to the seizure onset zone [2, 3] or symptomatology [4]. These dipoles are considered to originate from the temporal tip, superior temporal plane and basal temporal cortex [1]. The scalp EEG/MEG dipole is the summation of cortical activity over a wide area because extensive epileptic activity is required to produce adequate electrical potentials/magnetic fields detectable through the skull and scalp [1, 5]. Little is known about the relationship between actual cortical activities and MEG findings [6]. This study estimated interictal spike dipoles by MEG for comparison with electrocorticography (ECoG) findings. 2 Subjects and methods Three consecutive patients with TLE underwent EEG/MEG
Clinical Neurophysiology, 2013
Inter-hemispheric coherence is decreased during the final stage of corpus callosotomy and the eff... more Inter-hemispheric coherence is decreased during the final stage of corpus callosotomy and the effect is maximized after sectioning is completed. Various patterns of coherence decrease suggest individual variations in the participation of the corpus callosum in the genesis of bilateral synchrony. Intra-operative monitoring of inter-hemispheric EEG coherence with wavelet transform coherence and trend analysis techniques is useful to estimate the physiological completeness of callosal sectioning.
PLoS ONE, 2013
Epileptic seizure is a paroxysmal and self-limited phenomenon characterized by abnormal hypersync... more Epileptic seizure is a paroxysmal and self-limited phenomenon characterized by abnormal hypersynchrony of a large population of neurons. However, our current understanding of seizure dynamics is still limited. Here we propose a novel in vivo model of seizure-like afterdischarges using optogenetics, and report on investigation of directional network dynamics during seizure along the septo-temporal (ST) axis of hippocampus. Repetitive pulse photostimulation was applied to the rodent hippocampus, in which channelrhodopsin-2 (ChR2) was expressed, under simultaneous recording of local field potentials (LFPs). Seizure-like afterdischarges were successfully induced after the stimulation in both W-TChR2V4 transgenic (ChR2V-TG) rats and in wild type rats transfected with adeno-associated virus (AAV) vectors carrying ChR2. Pulse frequency at 10 and 20 Hz, and a 0.05 duty ratio were optimal for afterdischarge induction. Immunohistochemical c-Fos staining after a single induced afterdischarge confirmed neuronal activation of the entire hippocampus. LFPs were recorded during seizure-like afterdischarges with a multi-contact array electrode inserted along the ST axis of hippocampus. Granger causality analysis of the LFPs showed a bidirectional but asymmetric increase in signal flow along the ST direction. State space presentation of the causality and coherence revealed three discrete states of the seizure-like afterdischarge phenomenon: 1) resting state; 2) afterdischarge initiation with moderate coherence and dominant septal-to-temporal causality; and 3) afterdischarge termination with increased coherence and dominant temporal-to-septal causality. A novel in vivo model of seizure-like afterdischarge was developed using optogenetics, which was advantageous in its reproducibility and artifact-free electrophysiological observations. Our results provide additional evidence for the potential role of hippocampal septo-temporal interactions in seizure dynamics in vivo. Bidirectional networks work hierarchically along the ST hippocampus in the genesis and termination of epileptic seizures.
Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology, Jan 30, 2015
IEICE Proceeding Series, 2014
Masui. The Japanese journal of anesthesiology
In surgeries for epilepsy, electrocorticography (ECoG) enables tailored resection of the epilepto... more In surgeries for epilepsy, electrocorticography (ECoG) enables tailored resection of the epileptogenic brain and pharmacological stimulation should be employed in surgeries under general anesthesia. To identify the efficacy of continuous remifentanil in surgeries for epilepsy, ECoG findings with remifentanil and those with sevoflurane were compared. Sixteen patients with intractable epilepsy were included with institutional ethics committee approval and informed consent. General anesthesia was induced and maintained with sevoflurane, remifentanil and rocuronium. After dural opening, ECoG recordings were obtained before stimulation, with sevoflurane-stimulation (ET-sevoflurane 2.5%) and with remifentanil-stimulation (0.7 microg x kg(-1) x min(-1) for 2 min followed by 0.35 microg x kg(-1) x min(-1)). In 11 of the 16 cases, activation was confirmed with remifentanil and numbers of spikes with remifentanil- and sevoflurane-stimulation were larger than those before stimulation. There ha...
Epileptic Disorders International Epilepsy Journal With Videotape, Oct 1, 2010
Objective. To determine whether patients with neocortical epilepsy show evidence for increased ex... more Objective. To determine whether patients with neocortical epilepsy show evidence for increased excitability measured by cortico-cortical evoked potentials (CCEPs) in ictal-onset regions. Methods. In patients undergoing intracranial recordings with subdural electrodes for epilepsy surgery, we measured amplitudes, latencies, and stimulus thresholds of CCEPs near ictal onset zones (iCCEPs), and compared with adjacent neocortex not associated with ictal EEG (nCCEP). CCEP amplitude and latency measurements were made with each stimulation site, using graded stimulation intensities. Results. Ten patients were included in this study. CCEPs were recorded in eight of 10 patients. The first negative (N1) iCCEP amplitude was higher than that of nCCEP in seven of the eight patients. In the group analysis, this difference was statistically significant. In three of these patients, the difference was individually significant. In one patient, the amplitude was higher in nCCEP than iCCEP and the area selected as nCCEP was within primary eloquent cortex. There was no significant difference seen in latency changes or stimulus threshold. Conclusions. Accentuated CCEP amplitudes near ictal onset zones could reflect an increased excitability of the cortex associated with the epileptogenic zone in some patients with neocortical epilepsy. The response of the neocortex to lowfrequency stimulation may vary depending on the presence or absence of intrinsic epileptogenicity.
Rinsho Shinkeigaku, 2015
Anti-glutamic acid decarboxylase (GAD) antibodies are known to be associated with insulin-depende... more Anti-glutamic acid decarboxylase (GAD) antibodies are known to be associated with insulin-dependent diabetes mellitus (IDDM), stiff-person syndrome, and other neurological symptoms including temporal lobe epilepsy (TLE), known as autoimmune epilepsy. We treated four patients with TLE who had elevated titers of serum anti-GAD antibody (anti-GAD-Ab), higher than 100 U/ml. Three of the four patients started to have epileptic seizures in their 5th or 6th decade. Characteristic symptoms suggesting encephalitis or encephalopathy were absent at onset of these symptoms, which led to delayed diagnosis. All four patients developed two or three of cerebellar ataxia, neuropsychological impairment, and IDDM, by several years or decades after onset of TLE, even after seizure freedom in two patients. These abnormalities were indicators for suspecting the involvement of anti-GAD-Ab in the pathogenesis. Anti-GAD-Ab levels in the cerebrospinal fluid (CSF) were measured, which detected elevated CSF/serum anti-GAD-Ab ratio (≥ 1.0), suggesting intrathecal anti-GAD-Ab synthesis, in three of the four patients. The TLE symptoms were somewhat prolonged, but three of the four patients eventually achieved seizure freedom after immunotherapies with combinations of two or three anti-epileptic drugs. Serum anti-GAD Ab is recommended to be measured in patients with middle-aged onset TLE. Moreover, immune-modulating therapies including steroid pulse and intravenous immunoglobulin therapies could have ameliorated neurological complications, even in the chronic phase.
Journal of neurosurgery, 2014
Maximum resection of gliomas with minimum surgical complications usually leads to optimum outcome... more Maximum resection of gliomas with minimum surgical complications usually leads to optimum outcomes for patients. Radical resection of insulo-opercular gliomas is still challenging, and selection of ideal patients can reduce risk and obtain better outcomes. This retrospective study included 83 consecutively treated patients with newly diagnosed gliomas located at the insulo-opercular region and extending to the sylvian fissure around the primary motor and somatosensory cortices. The authors selected 4 characteristics as surgical indicators: clear tumor boundaries, negative enhancement, intact lenticulostriate arteries, and intact superior extremity of the central insular sulcus. Univariate analysis showed that tumors with clear boundaries were associated with higher rates of gross-total resection than were tumors with ambiguous boundaries (75.7% vs 19.6%). Tumors with negative enhancement compared with enhanced tumors were associated with lower frequency of tumor progression (32.0% v...
Neurologia medico-chirurgica, 2014
Resection of insulo-opercular gliomas carries the risk of postoperative hemiparesis caused by isc... more Resection of insulo-opercular gliomas carries the risk of postoperative hemiparesis caused by ischemia of the corona radiata resulting from injury to the long insular arteries. However, intraoperative identification of these perforating arteries is challenging. We attempted intra-operative motor evoked potential (MEP) monitoring under temporary occlusion of the suspected long insular artery arising from the opercular portion of middle cerebral artery in two patients with insulo-opercular gliomas. Temporary occlusion of the artery caused decrease in MEP amplitude, which recovered after release in one patient, who had no postoperative motor deficits or ischemic lesion in the corona radiata. Temporary occlusion of the artery caused no changes in MEP amplitude, so that the artery was sacrificed for tumor removal in the other patient, who had no motor deficits but ischemic lesion was present in the corona radiata in the territory of the long insular artery sparing the descending motor pa...
No to hattatsu. Brain and development, 2013
No shinkei geka. Neurological surgery, 2009
A 37-year-old male and a 12-year-old female presented with non-lesional epilepsy arising from the... more A 37-year-old male and a 12-year-old female presented with non-lesional epilepsy arising from the supplementary motor area in the medial frontal cortex, manifesting as daily brief tonic seizures involving the bilateral extremities, which were intractable to multiple antiepileptic medications. During the seizure, there was no impairment of awareness, and the tonus was always higher in the limbs contralateral to the epileptogenic hemisphere in both patients. Scalp EEG detected midline epileptiform discharges. Three-tesla MR imaging using the FLAIR and short tau inversion recovery sequences, interictal IMP-SPECT, IMZ-SPECT, and FDG-PET detected no focal abnormalities in either patient. Invasive intracranial EEG evaluation was performed using chronically implanted subdural electrodes on the interhemispheric frontoparietal cortices, based mainly on the seizure semiology and the associated EEG findings. Intracranial EEG successfully identified the location of the seizure onset in the supp...
Epilepsia, 2005
Objectively to evaluate whether independent spike detection by human interpreters is clinically v... more Objectively to evaluate whether independent spike detection by human interpreters is clinically valid in magnetoencephalography (MEG) and to characterize detection differences between MEG and scalp electroencephalography (EEG). We simultaneously recorded scalp EEG and MEG data from 43 patients with intractable focal epilepsy. Raw EEG and MEG waveforms were reviewed independently by two experienced epileptologists, one for EEG and one for MEG, blinded to the other modality and to the clinical information. The number and localization of spikes detected by EEG and/or MEG were compared in relation to clinical diagnosis based on postoperative seizure freedom. Interictal spikes were captured in both EEG and MEG in 31, in MEG alone in eight, in EEG alone in one, and in neither modality in three patients. The number of detections ranged widely with no statistical difference between modalities. A median of 25.7% of total spikes was detectable by both modalities. Spike localization was similarly consistent with the epilepsy diagnosis in 85.2% (EEG) and 78.1% (MEG) of the patients. Inaccurate localization occurred only in those cases with very few spikes detected, especially when the detections were in one modality alone. Interictal epileptiform discharges are easily perceived in MEG. Independent spike identification in MEG can provide clinical results comparable, but not superior, to EEG. Many spikes were seen in only one modality or the other; therefore the use of both EEG and MEG may provide additional information.
md?type= text.html Montrouge, 20-04-2019 Masaki Iwasaki You will find below the electronic reprin... more md?type= text.html Montrouge, 20-04-2019 Masaki Iwasaki You will find below the electronic reprint of your article (pdf format): Ictal deafness in drug-resistant MRI-negative epilepsy
Epileptic encephalopathy with electrical status epilepticus during sleep (ESES) is often refracto... more Epileptic encephalopathy with electrical status epilepticus during sleep (ESES) is often refractory to medical treatment and leads to poor cognitive outcomes. Corpus callosotomy may be an effective treatment option for drug-resistant ESES with no focal etiology. We retrospectively identified three patients who underwent corpus callosotomy for drug-resistant ESES in our institution. Electroencephalography (EEG) findings and cognitive functions were evaluated before surgery, at 3 months, 6 months, 1 year, and 2 years after surgery. Age at surgery was 6 years 10 months, 7 years 9 months, and 8 years 4 months, respectively. Period between the diagnosis of ESES and surgery ranged from 7 to 25 months. All patients had no obvious structural abnormalities and presented with cognitive decline despite multiple antiseizure medications and steroid therapies. One patient showed complete resolution of ESES and an improvement of intelligence quotient after surgery. Epileptiform EEG was lateralized to one hemisphere after surgery and spike wave index (SWI) was decreased with moderate improvement in development and seizures in the other 2 patients. SWI re-exacerbated from 6 months after surgery, but without subsequent developmental regression in these 2 patients. Corpus callosotomy may become an important treatment option for drug-resistant ESES in patients with no structural abnormalities.
urgical treatment for patients with drug-resistant focal epilepsy is efficacious in both adults a... more urgical treatment for patients with drug-resistant focal epilepsy is efficacious in both adults and children. 1,2 The primary goal of epilepsy surgery is to control a patient's seizures. Another important goal in pediatric patients is to prevent the cognitive and developmental stagnation or regression induced by persistent epileptic activity. Surgically treatable etiologies, such as hemimegalencephaly and focal cortical dysplasia, can cause severe seizures in infants, complicated by developmental epileptic encephalopathy such as early infantile epileptic encephalopathy or West syndrome. 3 Infants with a large or hemispheric epileptogenic lesion
Objectives: We developed a Markov model to simulate a treatment flow of epilepsy patients who ref... more Objectives: We developed a Markov model to simulate a treatment flow of epilepsy patients who refer to specialized care from non-specialized care, and to surgery from specialized care for estimation of patient distributions and expenditures caused by increasing the referral rate for specialized care. Methods: This budget impact analysis of treatment flow optimization in epilepsy patients was performed as a long-term simulation using the Markov model by comparing the current treatment flow and the optimized treatment flow. In the model, we simulated the prognosis of new onset 5-yearold epilepsy patients (assuming to represent epilepsy occurring between 0 and 10 years of age) treated over a lifetime period. Direct costs of pharmacotherapies, management fees and surgeries are included in the analysis to evaluate the annual budget impact in Japan. Results: In the current treatment flow, the number of refractory patients treated with four drugs by non-specialized care were estimated as 8766 and yielded JPY5.8 billion annually. However, in the optimized treatment flow, the number of patients treated with four drugs by non-specialized care significantly decreased and who continued the monotherapy increased. The costs for the four-drug therapy by non-specialized care were eliminated. Hence cost-saving of JPY9.5 billion (-5% of the current treatment flow) in total national expenditures would be expected. Conclusion: This study highlights that any policy decision-making for referral optimization to specialized care in appropriate epilepsy patients would be feasible with a cost-savings or very few budget impacts. However, important information in the decision-making such as transition probability to the next therapy or excuse for sensitive limitations is not available currently. Therefore, further research with reliable data such as big data analysis or a national survey with real-world treatment patterns is needed.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Epileptic disorders : international epilepsy journal with videotape, Jan 16, 2015
The primary motor cortex of the oro-facial level can be removed without permanent deficits, becau... more The primary motor cortex of the oro-facial level can be removed without permanent deficits, because of the bilateral representation of the innate functions. In contrast, resective surgery of the hand motor cortex or higher levels presents more challenges. We treated two adult patients with intractable epilepsy caused by small focal cortical dysplasia in the pre-central gyrus located between the foot and hand primary motor cortices. Focal cortical resection was guided by cortical EEG and intra-operative motor evoked potential, resulting in seizure freedom without neurological deficits in both cases. These cases illustrate that resective surgery can be safely performed in the primary motor cortex even dorsal to the oro-facial level, as long as the critical regions of the hand and foot motor cortices remain intact. Accurate delineation of the anatomical lesion and functional areas using intra-operative neurophysiological monitoring is crucial for successful outcome of the surgery.
Introduction Interictal MEG dipoles associated with temporal lobe epilepsy (TLE) can be classifie... more Introduction Interictal MEG dipoles associated with temporal lobe epilepsy (TLE) can be classified according to localization and orientation into anterior temporal horizontal (ATH), anterior temporal vertical and posterior temporal vertical (PTV) dipoles [1, 2, 3]. The MEG dipole pattern may be related to the seizure onset zone [2, 3] or symptomatology [4]. These dipoles are considered to originate from the temporal tip, superior temporal plane and basal temporal cortex [1]. The scalp EEG/MEG dipole is the summation of cortical activity over a wide area because extensive epileptic activity is required to produce adequate electrical potentials/magnetic fields detectable through the skull and scalp [1, 5]. Little is known about the relationship between actual cortical activities and MEG findings [6]. This study estimated interictal spike dipoles by MEG for comparison with electrocorticography (ECoG) findings. 2 Subjects and methods Three consecutive patients with TLE underwent EEG/MEG
Clinical Neurophysiology, 2013
Inter-hemispheric coherence is decreased during the final stage of corpus callosotomy and the eff... more Inter-hemispheric coherence is decreased during the final stage of corpus callosotomy and the effect is maximized after sectioning is completed. Various patterns of coherence decrease suggest individual variations in the participation of the corpus callosum in the genesis of bilateral synchrony. Intra-operative monitoring of inter-hemispheric EEG coherence with wavelet transform coherence and trend analysis techniques is useful to estimate the physiological completeness of callosal sectioning.
PLoS ONE, 2013
Epileptic seizure is a paroxysmal and self-limited phenomenon characterized by abnormal hypersync... more Epileptic seizure is a paroxysmal and self-limited phenomenon characterized by abnormal hypersynchrony of a large population of neurons. However, our current understanding of seizure dynamics is still limited. Here we propose a novel in vivo model of seizure-like afterdischarges using optogenetics, and report on investigation of directional network dynamics during seizure along the septo-temporal (ST) axis of hippocampus. Repetitive pulse photostimulation was applied to the rodent hippocampus, in which channelrhodopsin-2 (ChR2) was expressed, under simultaneous recording of local field potentials (LFPs). Seizure-like afterdischarges were successfully induced after the stimulation in both W-TChR2V4 transgenic (ChR2V-TG) rats and in wild type rats transfected with adeno-associated virus (AAV) vectors carrying ChR2. Pulse frequency at 10 and 20 Hz, and a 0.05 duty ratio were optimal for afterdischarge induction. Immunohistochemical c-Fos staining after a single induced afterdischarge confirmed neuronal activation of the entire hippocampus. LFPs were recorded during seizure-like afterdischarges with a multi-contact array electrode inserted along the ST axis of hippocampus. Granger causality analysis of the LFPs showed a bidirectional but asymmetric increase in signal flow along the ST direction. State space presentation of the causality and coherence revealed three discrete states of the seizure-like afterdischarge phenomenon: 1) resting state; 2) afterdischarge initiation with moderate coherence and dominant septal-to-temporal causality; and 3) afterdischarge termination with increased coherence and dominant temporal-to-septal causality. A novel in vivo model of seizure-like afterdischarge was developed using optogenetics, which was advantageous in its reproducibility and artifact-free electrophysiological observations. Our results provide additional evidence for the potential role of hippocampal septo-temporal interactions in seizure dynamics in vivo. Bidirectional networks work hierarchically along the ST hippocampus in the genesis and termination of epileptic seizures.
Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology, Jan 30, 2015
IEICE Proceeding Series, 2014
Masui. The Japanese journal of anesthesiology
In surgeries for epilepsy, electrocorticography (ECoG) enables tailored resection of the epilepto... more In surgeries for epilepsy, electrocorticography (ECoG) enables tailored resection of the epileptogenic brain and pharmacological stimulation should be employed in surgeries under general anesthesia. To identify the efficacy of continuous remifentanil in surgeries for epilepsy, ECoG findings with remifentanil and those with sevoflurane were compared. Sixteen patients with intractable epilepsy were included with institutional ethics committee approval and informed consent. General anesthesia was induced and maintained with sevoflurane, remifentanil and rocuronium. After dural opening, ECoG recordings were obtained before stimulation, with sevoflurane-stimulation (ET-sevoflurane 2.5%) and with remifentanil-stimulation (0.7 microg x kg(-1) x min(-1) for 2 min followed by 0.35 microg x kg(-1) x min(-1)). In 11 of the 16 cases, activation was confirmed with remifentanil and numbers of spikes with remifentanil- and sevoflurane-stimulation were larger than those before stimulation. There ha...
Epileptic Disorders International Epilepsy Journal With Videotape, Oct 1, 2010
Objective. To determine whether patients with neocortical epilepsy show evidence for increased ex... more Objective. To determine whether patients with neocortical epilepsy show evidence for increased excitability measured by cortico-cortical evoked potentials (CCEPs) in ictal-onset regions. Methods. In patients undergoing intracranial recordings with subdural electrodes for epilepsy surgery, we measured amplitudes, latencies, and stimulus thresholds of CCEPs near ictal onset zones (iCCEPs), and compared with adjacent neocortex not associated with ictal EEG (nCCEP). CCEP amplitude and latency measurements were made with each stimulation site, using graded stimulation intensities. Results. Ten patients were included in this study. CCEPs were recorded in eight of 10 patients. The first negative (N1) iCCEP amplitude was higher than that of nCCEP in seven of the eight patients. In the group analysis, this difference was statistically significant. In three of these patients, the difference was individually significant. In one patient, the amplitude was higher in nCCEP than iCCEP and the area selected as nCCEP was within primary eloquent cortex. There was no significant difference seen in latency changes or stimulus threshold. Conclusions. Accentuated CCEP amplitudes near ictal onset zones could reflect an increased excitability of the cortex associated with the epileptogenic zone in some patients with neocortical epilepsy. The response of the neocortex to lowfrequency stimulation may vary depending on the presence or absence of intrinsic epileptogenicity.
Rinsho Shinkeigaku, 2015
Anti-glutamic acid decarboxylase (GAD) antibodies are known to be associated with insulin-depende... more Anti-glutamic acid decarboxylase (GAD) antibodies are known to be associated with insulin-dependent diabetes mellitus (IDDM), stiff-person syndrome, and other neurological symptoms including temporal lobe epilepsy (TLE), known as autoimmune epilepsy. We treated four patients with TLE who had elevated titers of serum anti-GAD antibody (anti-GAD-Ab), higher than 100 U/ml. Three of the four patients started to have epileptic seizures in their 5th or 6th decade. Characteristic symptoms suggesting encephalitis or encephalopathy were absent at onset of these symptoms, which led to delayed diagnosis. All four patients developed two or three of cerebellar ataxia, neuropsychological impairment, and IDDM, by several years or decades after onset of TLE, even after seizure freedom in two patients. These abnormalities were indicators for suspecting the involvement of anti-GAD-Ab in the pathogenesis. Anti-GAD-Ab levels in the cerebrospinal fluid (CSF) were measured, which detected elevated CSF/serum anti-GAD-Ab ratio (≥ 1.0), suggesting intrathecal anti-GAD-Ab synthesis, in three of the four patients. The TLE symptoms were somewhat prolonged, but three of the four patients eventually achieved seizure freedom after immunotherapies with combinations of two or three anti-epileptic drugs. Serum anti-GAD Ab is recommended to be measured in patients with middle-aged onset TLE. Moreover, immune-modulating therapies including steroid pulse and intravenous immunoglobulin therapies could have ameliorated neurological complications, even in the chronic phase.
Journal of neurosurgery, 2014
Maximum resection of gliomas with minimum surgical complications usually leads to optimum outcome... more Maximum resection of gliomas with minimum surgical complications usually leads to optimum outcomes for patients. Radical resection of insulo-opercular gliomas is still challenging, and selection of ideal patients can reduce risk and obtain better outcomes. This retrospective study included 83 consecutively treated patients with newly diagnosed gliomas located at the insulo-opercular region and extending to the sylvian fissure around the primary motor and somatosensory cortices. The authors selected 4 characteristics as surgical indicators: clear tumor boundaries, negative enhancement, intact lenticulostriate arteries, and intact superior extremity of the central insular sulcus. Univariate analysis showed that tumors with clear boundaries were associated with higher rates of gross-total resection than were tumors with ambiguous boundaries (75.7% vs 19.6%). Tumors with negative enhancement compared with enhanced tumors were associated with lower frequency of tumor progression (32.0% v...
Neurologia medico-chirurgica, 2014
Resection of insulo-opercular gliomas carries the risk of postoperative hemiparesis caused by isc... more Resection of insulo-opercular gliomas carries the risk of postoperative hemiparesis caused by ischemia of the corona radiata resulting from injury to the long insular arteries. However, intraoperative identification of these perforating arteries is challenging. We attempted intra-operative motor evoked potential (MEP) monitoring under temporary occlusion of the suspected long insular artery arising from the opercular portion of middle cerebral artery in two patients with insulo-opercular gliomas. Temporary occlusion of the artery caused decrease in MEP amplitude, which recovered after release in one patient, who had no postoperative motor deficits or ischemic lesion in the corona radiata. Temporary occlusion of the artery caused no changes in MEP amplitude, so that the artery was sacrificed for tumor removal in the other patient, who had no motor deficits but ischemic lesion was present in the corona radiata in the territory of the long insular artery sparing the descending motor pa...
No to hattatsu. Brain and development, 2013
No shinkei geka. Neurological surgery, 2009
A 37-year-old male and a 12-year-old female presented with non-lesional epilepsy arising from the... more A 37-year-old male and a 12-year-old female presented with non-lesional epilepsy arising from the supplementary motor area in the medial frontal cortex, manifesting as daily brief tonic seizures involving the bilateral extremities, which were intractable to multiple antiepileptic medications. During the seizure, there was no impairment of awareness, and the tonus was always higher in the limbs contralateral to the epileptogenic hemisphere in both patients. Scalp EEG detected midline epileptiform discharges. Three-tesla MR imaging using the FLAIR and short tau inversion recovery sequences, interictal IMP-SPECT, IMZ-SPECT, and FDG-PET detected no focal abnormalities in either patient. Invasive intracranial EEG evaluation was performed using chronically implanted subdural electrodes on the interhemispheric frontoparietal cortices, based mainly on the seizure semiology and the associated EEG findings. Intracranial EEG successfully identified the location of the seizure onset in the supp...