Publications by authors named "Riki Matsumoto"

143 Publications

Frequency-Dependent Cortical Interactions during Semantic Processing: An Electrocorticogram Cross-spectrum Analysis Using a Semantic Space Model.

Cereb Cortex 2021 May 4. Epub 2021 May 4.

Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, Sakyo, Kyoto 606-8507, Japan.

Convergent evidence has demonstrated that semantics are represented by the interaction between a multimodal semantic hub at the anterior temporal lobe (ATL) and other modality-specific association cortical areas. Electrocorticogram (ECoG) recording with high spatiotemporal resolutions is efficient in evaluating such cortical interactions; however, this has not been a focus of preceding studies. The present study evaluated cortical interactions during picture naming using a novel ECoG cross-spectrum analysis, which was formulated from a computational simulation of neuronal networks and combined with a vector space model of semantics. The results clarified three types of frequency-dependent cortical networks: 1) an earlier-period (0.2-0.8 s from stimulus onset) high-gamma-band (90-150 Hz) network with a hub at the posterior fusiform gyrus, 2) a later-period (0.4-1.0 s) beta-band (15-40 Hz) network with multiple hubs at the ventral ATL and posterior middle temporal gyrus, and 3) a pre-articulation theta-band (4-7 Hz) network distributed over widely located cortical regions. These results suggest that frequency-dependent cortical interactions can characterize the underlying processes of semantic cognition, and the beta-band network with a hub at the ventral ATL is especially associated with the formation of semantic representation.
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http://dx.doi.org/10.1093/cercor/bhab089DOI Listing
May 2021

Effects of a stable concentration of propofol on interictal high-frequency oscillations in drug-resistant epilepsy.

Epileptic Disord 2021 Apr 14. Epub 2021 Apr 14.

Department of Neurosurgery, Kyoto University Graduate School of Medicine, 54, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan.

The aim of this study was to clarify the effect of a stable concentration of propofol on interictal high-frequency oscillations (HFOs), which may contribute to identifying the epileptogenic zone intraoperatively for resection surgery. Nine patients with drug-resistant focal epilepsy who underwent invasive pre-surgical evaluation with chronic subdural electrodes were recruited. Five-minute electrocorticograms during wakefulness, slow-wave sleep, and under a stable brain concentration of propofol were recorded with the same electrodes. In each patient, 1-10 pairs of electrodes were selected for both electrodes with EEG changes within 5 seconds from the ictal onset (ictal pattern for 5 seconds [IP5]) and those outside the area of IP5 with no interictal epileptiform discharges (non-epileptiform [nEPI]). The numbers of ripples (80-250 Hz) and fast ripples (>250 Hz) were measured semi-automatically using an established algorithm. Statistical testing was performed with a mixed effect model. Thirty-seven pairs of electrodes from nine patients were analysed for IP5 and 29 pairs from seven patients were analysed for nEPI. The numbers of HFOs differed between the areas (IP5 and nEPI) and among the conditions (wakefulness, slow-wave sleep, propofol anaesthesia) (all p <0.01). The HFO occurrence rates were significantly higher for IP5 than those for nEPI in all conditions (for both ripples and fast ripples in all conditions; p <0.01). The occurrence rates of HFOs for IP5 were significantly higher than those for nEPI under propofol anaesthesia. These are fundamental findings for intraoperative HFO analysis, however, the following limitations should be considered: physiological HFOs could not be completely differentiated from pathological HFOs; in order to apply an HFO detector, an appropriate cut-off threshold is needed; an artefact of the impulse response filter appears as an HFO; and the series was comprised of a small number of heterogeneous patients.
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http://dx.doi.org/10.1684/epd.2021.1264DOI Listing
April 2021

Cortico-cortical evoked potential by single-pulse electrical stimulation is a generally safe procedure.

Clin Neurophysiol 2021 May 3;132(5):1033-1040. Epub 2021 Feb 3.

Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, Japan. Electronic address:

Objective: Cortico-cortical evoked potential (CCEP) by single-pulse electrical stimulation (SPES) is useful to investigate effective connectivity and cortical excitability. We aimed to clarify the safety of CCEPs.

Methods: We retrospectively analyzed 29 consecutive patients with intractable partial epilepsy undergoing chronic subdural grid implantation and CCEP recording. Repetitive SPES (1 Hz) was systematically applied to a pair of adjacent electrodes over almost all electrodes. We evaluated the incidences of afterdischarges (ADs) and clinical seizures.

Results: Out of 1283 electrode pairs, ADs and clinical seizures were observed in 12 and 5 pairs (0.94% and 0.39%, per electrode pair) in 7 and 3 patients (23.3% and 10.0%, per patient), respectively. Of the 18-82 pairs per patient, ADs and clinical seizures were induced in 0-4 and 0-3 pairs, respectively. Stimulating 4 SOZ (seizure onset zone) (2.5%) and 8 non-SOZ pairs (0.75%) resulted in ADs. We observed clinical seizures in stimulating 4 SOZ (2.5%) and 1 non-SOZ pair (0.09%). The incidence of clinical seizures varied significantly between SOZ and non-SOZ stimulations (p = 0.001), while the difference in AD incidence tended towards significance (p = 0.058).

Conclusion: Although caution should be taken in stimulating SOZ, CCEP is a safe procedure for presurgical evaluation.

Significance: CCEP is safe under the established protocol.
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http://dx.doi.org/10.1016/j.clinph.2020.12.022DOI Listing
May 2021

Intraoperative Brain Mapping by Cortico-Cortical Evoked Potential.

Front Hum Neurosci 2021 18;15:635453. Epub 2021 Feb 18.

Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.

To preserve postoperative brain function, it is important for neurosurgeons to fully understand the brain's structure, vasculature, and function. Intraoperative high-frequency electrical stimulation during awake craniotomy is the gold standard for mapping the function of the cortices and white matter; however, this method can only map the "focal" functions and cannot monitor large-scale cortical networks in real-time. Recently, an electrophysiological method using cortico-cortical evoked potentials (CCEPs) induced by single-pulse electrical cortical stimulation has been developed in an extraoperative setting. By using the CCEP connectivity pattern intraoperatively, mapping and real-time monitoring of the dorsal language pathway is available. This intraoperative CCEP method also allows for mapping of the frontal aslant tract, another language pathway, and detection of connectivity between the primary and supplementary motor areas in the frontal lobe network. Intraoperative CCEP mapping has also demonstrated connectivity between the frontal and temporal lobes, likely the ventral language pathway. Establishing intraoperative electrophysiological monitoring is clinically useful for preserving brain function, even under general anesthesia. This CCEP technique demonstrates potential clinical applications for mapping and monitoring large-scale cortical networks.
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http://dx.doi.org/10.3389/fnhum.2021.635453DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7930065PMC
February 2021

Genetic Variations and Neuropathologic Features of Patients With PRKN Mutations.

Mov Disord 2021 Feb 11. Epub 2021 Feb 11.

Department of Pathology, Brain Research Institute, Niigata University, Niigata, Japan.

Background: Mutations in PRKN are the most common cause of autosomal recessive juvenile parkinsonism. The objective of this study was to investigate the association between genotype and pathology in patients with PRKN mutations.

Methods: We performed a sequence and copy number variation analysis of PRKN, mRNA transcripts, Parkin protein expression, and neuropathology in 8 autopsied patients.

Results: All the patients harbored biallelic PRKN mutations. Two patients were homozygous and heterozygous, respectively, for the missense mutation p.C431F. Seven patients had exon rearrangements, including 2 patients from a single family who harbored a homozygous deletion of exon 4, and 3 patients who carried a homozygous duplication of exons 6-7, a homozygous duplication of exons 10-11, and a heterozygous duplication of exons 2-4. In the other 2 patients, we found a compound heterozygous duplication of exon 2, deletion of exon 3, and a heterozygous duplication of exon 2. However, sequencing of cDNA prepared from mRNA revealed 2 different transcripts derived from triplication of exon 2 and deletion of exons 2-3 and from duplication of exons 2-4 and deletion of exons 3-4. Western blotting and immunohistochemistry revealed faint or no expression of Parkin in their brains. In the substantia nigra pars compacta, a subfield-specific pattern of neuronal loss and mild gliosis were evident. Lewy bodies were found in 3 patients. Peripheral sensory neuronopathy was a feature.

Conclusions: Genomic and mRNA analysis is needed to identify the PRKN mutations. Variable mutations may result in no or little production of mature Parkin and the histopathologic features may be similar.
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http://dx.doi.org/10.1002/mds.28521DOI Listing
February 2021

[A case of spinal cord infarction accompanied with neuromyelitis optica spectrum pathophysiology].

Rinsho Shinkeigaku 2021 Feb 26;61(2):127-131. Epub 2021 Jan 26.

Division of Neurology, Kobe University Graduate School of Medicine.

We report a 60-year-old woman who developed spinal cord infarction (SCI) with anti-aquaporin (AQP) 4 antibody seropositive. She was admitted to our hospital with acute onset of flaccid paraparesis and urinary disturbances that completed within a few minutes after acute pain in her lower back. Neurological examination revealed flaccid paraparesis, bladder and bowel dysfunction and dissociated sensory loss below the level of Th11 spinal cord segment. Diffusion weighted imaging (DWI) and T-wighted imaging (TWI) of thoracic spine MRI showed high signal intensity in the spinal cord between Th9 and Th12 vertebral levels with decreased apparent diffusion coefficient (ADC). We diagnosed her as having SCI. Thereafter the serum examination on admission was reported as positive for anti-aquaporin 4 (AQP4) antibody. Cerebrospinal fluid (CSF) analysis revealed pleocytosis, and the spinal cord lesions became enlarged in MRI on 12 days after the onset. We, therefore, suspected that the pathophysiology of neuromyelitis optica spectrum disorder (NMOSD) accompanied SCI. The patient underwent two courses of high dose intravenous methylprednisolone (IVMP) for three days (1 g/day). Her neurological symptoms did not improve significantly, but the size of TWI MRI high signal lesion improved to that of the initial MRI scan. Anti-AQP4 antibody seropositivity may have modified the SCI pathology in the present patient.
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http://dx.doi.org/10.5692/clinicalneurol.cn-001535DOI Listing
February 2021

Prescription patterns of antiepileptic drugs for adult patients with newly diagnosed focal epilepsy from 2006 to 2017 in Japan.

Epilepsy Res 2021 Jan 18;169:106503. Epub 2020 Nov 18.

Department of Pharmacoepidemiology, Graduate School of Medicine and Public Health, Kyoto University, Kyoto, Japan. Electronic address:

Objective: This study aimed to examine prescription patterns of antiepileptic drugs (AEDs) for adult patients with newly diagnosed focal epilepsy in Japan and whether these patterns adhere to the 2010 Japanese Society of Neurology Guidelines of Epilepsy Treatment.

Methods: Data from the JMDC Claims Database were obtained for patients aged between 20 and 65 years with newly diagnosed focal epilepsy who were prescribed AEDs between 2006 and 2017. Available prescription information up to the patient's first year was recorded and longitudinal descriptive statistics, Cochran Armitage Trend (CAT) tests, and annual percentage change (APC) were used to analyze AED trends and overall guideline adherence. In addition, logistic regression analyses were used to compare these results across different health facilities.

Results: A total of 6024 adult patients with newly diagnosed focal epilepsy were enrolled. The prescription of new AEDs increased significantly (CAT, p < 0.001, APC = 28.74 %) up to 36.8 % of all prescriptions in 2017 when compared to 2006. Among new AEDs, prescriptions for levetiracetam increased most rapidly and were followed by lamotrigine. In contrast, prescriptions for older AEDs, especially valproate, decreased over this same time period. The average guideline adherence rate from 2010 to 2017 was 75.3 %, and was not significantly different over time (CAT, p = 0.55). Health facilities with either more than 500 beds or between 20-499 beds had higher odds of prescribing new AEDs and improved guideline adherence when compared to facilities with 0-19 beds.

Conclusion: Prescription patterns of AEDs for adult patients with newly diagnosed focal epilepsy exhibited a trend from older to new AED classes between 2006 and 2017, with consistent, high guideline adherence from 2010 to 2017. Health facilities with 0-19 beds were less likely to prescribe new AEDs and completely adhere to proposed guidelines.
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http://dx.doi.org/10.1016/j.eplepsyres.2020.106503DOI Listing
January 2021

[Successful treatment of Guillain-Barré syndrome-like acute inflammatory demyelinating polyneuropathy caused by pembrolizumab with a combination of corticosteroid and immunoglobulins: a case report].

Rinsho Shinkeigaku 2020 Nov 27;60(11):773-777. Epub 2020 Oct 27.

Division of Neurology, Kobe University Graduate School of Medicine.

A 74-year-old man, who received pembrolizumab for the treatment for non-small cell lung cancer, developed quadriparesis 10 days after the first course of treatment accompanied by gait disturbance. Dysesthesia was observed in the distal extremities, and tendon reflexes were absent. Neurological examination and peripheral nerve conduction study supported the diagnosis of Guillain-Barré syndrome-like acute inflammatory demyelinating polyneuropathy caused by pembrolizumab. The administration of pembrolizumab was discontinued. Moreover, he was initially treated with intravenous immunoglobulin therapy, followed by intravenous methylprednisolone therapy and oral prednisolone. The limb weakness improved to a degree that he could walk alone on discharge. Pembrolizumab, which is an immune checkpoint inhibitor with a high anti-tumor effect, is reported to cause various adverse events. However, neuromuscular complications following cancer treatment with immune checkpoint inhibitors are relatively rare. Treatment with corticosteroids is considered to be effective for treating immune-related adverse events. Corticosteroids were effective in treating peripheral neuropathy caused by immune checkpoint inhibitors in this patient. Thorough treatment should be considered with a combination of corticosteroids and immunoglobulin therapy, in addition to discontinuation of immune checkpoint inhibitors, for this rare entity, which differs from that for idiopathic Guillain-Barré syndrome.
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http://dx.doi.org/10.5692/clinicalneurol.cn-001444DOI Listing
November 2020

Engagement of cortico-cortical and cortico-subcortical networks in a patient with epileptic spasms: An integrated neurophysiological study.

Clin Neurophysiol 2020 Sep 29;131(9):2255-2264. Epub 2020 May 29.

Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, 54, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address:

Objective: We aimed to delineate the engagement of cortico-cortical and cortico-subcortical networks in the generation of epileptic spasms (ES) using integrated neurophysiological techniques.

Methods: Seventeen-year-old male patient with intractable ES underwent chronic subdural electrode implantation for presurgical evaluation. Networks were evaluated in ictal periods using high-frequency oscillation (HFO) analysis and in interictal periods using magnetoencephalography (MEG) and simultaneous electroencephalography, and functional magnetic resonance imaging (EEG-fMRI). Cortico-cortical evoked potentials (CCEPs) were recorded to trace connections among the networks.

Results: Ictal HFO revealed a network comprising multilobar cortical regions (frontal, parietal, and temporal), but sparing the positive motor area. Interictally, MEG and EEG-fMRI revealed spike-and-wave-related activation in these cortical regions. Analysis of CCEPs provided evidence of connectivity within the cortico-cortical network. Additionally, EEG-fMRI results indicate the involvement of subcortical structures, such as bilateral thalamus (predominantly right) and midbrain.

Conclusions: In this case study, integrated neurophysiological techniques provided converging evidence for the involvement of a cortico-cortical network (sparing the positive motor area) and a cortico-subcortical network in the generation of ES in the patient.

Significance: Cortico-cortical and cortico-subcortical pathways, with the exception of the direct descending corticospinal pathway from the positive motor area, may play important roles in the generation of ES.
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http://dx.doi.org/10.1016/j.clinph.2020.04.167DOI Listing
September 2020

Progressive length-dependent polyneuropathy in xeroderma pigmentosum group A.

Muscle Nerve 2020 10 10;62(4):534-540. Epub 2020 Aug 10.

Division of Neurology, Kobe University Graduate School of Medicine, Kobe, Japan.

Background: In this study, we aimed to investigate the progression of peripheral nervous system involvement in xeroderma pigmentosum group A (XP-A).

Methods: We performed nerve conduction studies in 17 genetically confirmed XP-A patients and conducted follow-ups. Of these patients we also analyzed gray matter volume (GMV) using brain MRI and assessed the severity score of clinical and skin manifestation.

Results: We found significant reduction in the motor and sensory nerve action potential amplitude and mild reduction in conduction velocity. These findings were predominant in sensory nerves and the lower limbs, were observed since early childhood, and gradually deteriorated with age.

Conclusions: The electrophysiological characteristics of XP-A patients are consistent with length-dependent axonal polyneuropathy and there is progressive deterioration from early childhood.
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http://dx.doi.org/10.1002/mus.27028DOI Listing
October 2020

Electrical cortical stimulations modulate spike and post-spike slow-related high-frequency activities in human epileptic foci.

Clin Neurophysiol 2020 Aug 11;131(8):1741-1754. Epub 2020 May 11.

Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, Kyoto, Japan. Electronic address:

Objective: Using interictal epileptiform discharges (IEDs), consisting of spikes and post-spike slow waves (PSSs), and IED-related high-frequency activities (HFAs), we elucidated inhibitory effects of electrical cortical stimulation (ECS) on human epileptic foci.

Methods: We recruited 8 patients with intractable focal epilepsy, and 50-Hz ECS was applied to the seizure-onset zone (SOZ) and non-SOZ. Before (5-min) and after (20-min) ECS, we evaluated the number of IED, the amplitudes of spikes and PSSs, spike-related HFA power, and PSS-related low gamma (30-50 Hz) activities.

Results: SOZ stimulation significantly decreased the number of IEDs and amplitude of spikes. Spike-related HFA power values in fast ripple (200-300 Hz) and ripple (80-150 Hz) bands were significantly suppressed only by SOZ stimulation in 4 and 3 patients, respectively. Among 4 patients with discrete PSSs, the amplitude ratio of spike/PSS decreased and the PSS-related low gamma activity power increased significantly in 2 patients and marginally in 1 patient.

Conclusions: ECS potentially modulates cortical excitability by reducing excitation and increasing inhibition, and monitoring IED-related HFAs may help achieve the optimal effects of ECS.

Significance: IED and IED-related HFAs are dynamic, potential surrogate markers for epileptic excitability during the interictal period.
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http://dx.doi.org/10.1016/j.clinph.2020.03.042DOI Listing
August 2020

Anti-PDHA1 antibody is detected in a subset of patients with schizophrenia.

Sci Rep 2020 05 13;10(1):7906. Epub 2020 May 13.

Department of Rheumatology and Clinical Immunology, Kyoto University Graduate School of Medicine, Kyoto, Japan.

Autoantibodies have been implicated in schizophrenia aetiology. Here, novel autoantibodies were isolated from patients with schizophrenia. Autoantibody candidates were searched using two-dimensional gel electrophoresis and western blotting with rat brain proteins as antigens and two sera pools (25 schizophrenia patients versus 25 controls) as antibodies. Immunoreactive antigens were identified by mass spectrometry. Antibody prevalence were evaluated by western blotting using human recombinant proteins. Furthermore, brain magnetic resonance imaging data (regional brain volumes and diffusion tensor imaging measures) were compared. Two proteins of the mitochondrial respiration pathway were identified as candidate antigens. Three patients with schizophrenia, but no controls, expressed antibodies targeting one of the candidate antigens, i.e., pyruvate dehydrogenase E1 component subunit alpha, somatic form, mitochondrial (PDHA1, EC 1.2.4.1), which is related to mitochondrial energy production. Anti-PDHA1 antibody-positive patients (n = 3) had increased volumes in the left occipital fusiform gyrus compared to both controls (n = 23, p = 0.017) and antibody-negative patients (n = 16, p = 0.009), as well as in the left cuneus compared to antibody-negative patients (n = 16, p = 0.018). This is the first report of an anti-PDHA1 antibody in patients with schizophrenia. Compatible with recent findings of mitochondrial dysfunction in schizophrenia, this antibody may be involved in the pathogenesis of a specific subgroup of schizophrenia.
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http://dx.doi.org/10.1038/s41598-020-63776-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7220915PMC
May 2020

[A case of refractory generalized atonic seizure and hemifacial spasm with the possible causative pontocerebellar lesion].

Rinsho Shinkeigaku 2020 May 18;60(5):362-366. Epub 2020 Apr 18.

Department of Neurology, Kyoto University Graduate School of Medicine.

The patient was a 35-year-old woman. At the age of 1, she had undergone resection and radiation therapy for neoplastic lesions in the pons. She had a history of gelastic seizures when she was in elementary school, and brief lapses of the neck and truncal muscular tone and convulsions on the left face occurred at the age of 23. After a generalized sharp wave in the ictal electroencephalogram and electromyogram recording, left orbicularis oris muscle contraction was observed followed by sudden cervical extensor atonia. Seizure propagation was noted in the cerebral cortex, left facial nerve nucleus, and brainstem reticular formation. In a simultaneous electroencephalography with functional MRI, the blood oxygen level-dependent effect related to generalized sharp waves was observed in the vicinity of brainstem lesions in addition to a decrease in bilateral frontal and parietal lobes signals, as detected in generalized seizures. These findings suggest that the lesion could be a part of the epilepsy network. Although most epileptic seizures are derived from the cerebral cortex, it is important to note that brainstem lesions are involved in seizures in the patient presented in this study.
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http://dx.doi.org/10.5692/clinicalneurol.cn-001368DOI Listing
May 2020

[Pitfalls in Reading EEG for Temporal Lobe Epilepsy: The "Southern-hemisphere" Spike and Normal Variants].

Brain Nerve 2020 Apr;72(4):425-436

Division of Neurology, Kobe University Graduate School of Medicine.

Electroencephalogram (EEG) reading in clinical settings commonly uses three montage types: referential montage, bipolar montage, and average montage. Since each montage type has its advantages and disadvantages, there is no single best montage. To correctly read EEG, it is essential 1) to use the montage appropriate for the focus and distribution of epileptic activity and 2) to correctly recognize EEG waveforms that are often misdiagnosed as epileptic activity. In this article, we present the so-called "southern-hemisphere" epileptic activity, which is recognized as challenging to diagnose, along with two cases of temporal lobe epilepsy. Case 1 exhibited seizures that started with palpitations and epigastric discomfort, followed by loss of awareness and oral automatisms. Case 2 experienced recurrent episodes of syncope and was diagnosed with temporal lobe epilepsy based on EEG findings and the observed improvement with anti-epileptic medication. In both cases, the longitudinal bipolar montage ("double-banana montage") failed to visualize the epileptic activity, while the referential montages (ear lobe reference or average reference) clearly showed maximal activity at the earlobe electrode. Additionally, we present the normal variants of normal EEG waveforms that are often misdiagnosed as epileptic activity.
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http://dx.doi.org/10.11477/mf.1416201541DOI Listing
April 2020

Connectivity Gradient in the Human Left Inferior Frontal Gyrus: Intraoperative Cortico-Cortical Evoked Potential Study.

Cereb Cortex 2020 Jun;30(8):4633-4650

Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.

In the dual-stream model of language processing, the exact connectivity of the ventral stream to the anterior temporal lobe remains elusive. To investigate the connectivity between the inferior frontal gyrus (IFG) and the lateral part of the temporal and parietal lobes, we integrated spatiotemporal profiles of cortico-cortical evoked potentials (CCEPs) recorded intraoperatively in 14 patients who had undergone surgical resection for a brain tumor or epileptic focus. Four-dimensional visualization of the combined CCEP data showed that the pars opercularis (Broca's area) is connected to the posterior temporal cortices and the supramarginal gyrus, whereas the pars orbitalis is connected to the anterior lateral temporal cortices and angular gyrus. Quantitative topographical analysis of CCEP connectivity confirmed an anterior-posterior gradient of connectivity from IFG stimulus sites to the temporal response sites. Reciprocality analysis indicated that the anterior part of the IFG is bidirectionally connected to the temporal or parietal area. This study shows that each IFG subdivision has different connectivity to the temporal lobe with an anterior-posterior gradient and supports the classical connectivity concept of Dejerine; that is, the frontal lobe is connected to the temporal lobe through the arcuate fasciculus and also a double fan-shaped structure anchored at the limen insulae.
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http://dx.doi.org/10.1093/cercor/bhaa065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7325718PMC
June 2020

Could the 2017 ILAE and the four-dimensional epilepsy classifications be merged to a new "Integrated Epilepsy Classification"?

Seizure 2020 May 5;78:31-37. Epub 2020 Mar 5.

Neurocenter Bellevue, Zurich, Switzerland.

Over the last few decades the ILAE classifications for seizures and epilepsies (ILAE-EC) have been updated repeatedly to reflect the substantial progress that has been made in diagnosis and understanding of the etiology of epilepsies and seizures and to correct some of the shortcomings of the terminology used by the original taxonomy from the 1980s. However, these proposals have not been universally accepted or used in routine clinical practice. During the same period, a separate classification known as the "Four-dimensional epilepsy classification" (4D-EC) was developed which includes a seizure classification based exclusively on ictal symptomatology, which has been tested and adapted over the years. The extensive arguments for and against these two classification systems made in the past have mainly focused on the shortcomings of each system, presuming that they are incompatible. As a further more detailed discussion of the differences seemed relatively unproductive, we here review and assess the concordance between these two approaches that has evolved over time, to consider whether a classification incorporating the best aspects of the two approaches is feasible. To facilitate further discussion in this direction we outline a concrete proposal showing how such a compromise could be accomplished, the "Integrated Epilepsy Classification". This consists of five categories derived to different degrees from both of the classification systems: 1) a "Headline" summarizing localization and etiology for the less specialized users, 2) "Seizure type(s)", 3) "Epilepsy type" (focal, generalized or unknown allowing to add the epilepsy syndrome if available), 4) "Etiology", and 5) "Comorbidities & patient preferences".
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http://dx.doi.org/10.1016/j.seizure.2020.02.018DOI Listing
May 2020

Intraoperative Electrophysiologic Mapping of Medial Frontal Motor Areas and Functional Outcomes.

World Neurosurg 2020 06 4;138:e389-e404. Epub 2020 Mar 4.

Department of Neurosurgery, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto, Japan.

Objective: To propose a method for intraoperative mapping and monitoring of the medial frontal motor areas (MFMA).

Methods: We estimated the location of the MFMA using the corticocortical evoked potential (CCEP) provoked by electric stimuli to the primary motor area (M1) of the upper limb. We localized or defined the MFMA by recording the motor evoked potentials (MEPs) provoked by electric stimuli to the medial frontal cortex around the estimated area. We monitored the patients' motor function during awake craniotomy and sequentially recorded the MEPs of the upper and/or lower limbs. This method was applied to 8 patients.

Results: Four patients who had part of the areas identified as the MFMA removed showed transient hemiparesis postoperatively (supplementary motor area [SMA] syndrome). The MEP from the M1 was preserved in the 4 patients. The resection of the identified MFMA might have caused their SMA syndrome. The CCEP showed a strong connection between the M1 and the SMA of the upper limb. Our method did not provoke any seizures.

Conclusions: This is a safe and sensitive method for intraoperative mapping and monitoring of the MFMA by combining electrophysiologic monitoring and awake craniotomy. It is clinically useful for mapping the MFMA and can prevent permanent motor deficits.
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http://dx.doi.org/10.1016/j.wneu.2020.02.129DOI Listing
June 2020

Scalp EEG Could Record Both Ictal Direct Current Shift and High-Frequency Oscillation Together Even With a Time Constant of 2 Seconds.

J Clin Neurophysiol 2020 Mar;37(2):191-194

Department of Epilepsy, Movement Disorders, and Physiology, Kyoto University Graduate School of Medicine, Kyoto, Japan; and.

Herein, the authors report for the first time, scalp-recorded (1) focal ictal direct current (DC) shifts (active DC shifts; that precede conventional pattern) from the chronic focus of focal epilepsy and (2) ictal high-frequency oscillation after ictal DC shifts (passive DC shifts; that follow both conventional and high-frequency oscillation ictal patterns) from the acute focus of acute symptomatic seizures (Szs) in a 77-year-old man. Sixteen episodes of clinical Szs were recorded by scalp EEG with a 2-seconds time constant. Among the 16 recorded episodes of Sz, four EEG Sz patterns originated from the left posterior temporal area (chronic focus), and all patterns (100%) exhibited active DC shifts preceding the conventional pattern by 12 seconds. Twelve EEG Sz patterns originated from the right parietal area (acute focus), and the high-frequency oscillations (five Szs) (41.6%) and DC shifts (six Szs) (50%) occurred first, followed by the conventional pattern 8 seconds later. Because both the active and the passive DC shifts were recorded with a time constant of 2 seconds, which was smaller than that reported previously for ictal DC shifts (e.g., time constant of 10 seconds), clinically useful ictal DC shifts could be routinely inspected with a time constant of 2 seconds.
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http://dx.doi.org/10.1097/WNP.0000000000000670DOI Listing
March 2020

Visualizing prolonged hyperperfusion in post-stroke epilepsy using postictal subtraction SPECT.

J Cereb Blood Flow Metab 2021 Jan 16;41(1):146-156. Epub 2020 Feb 16.

Department of Neurology, National Cerebral and Cardiovascular Center, Osaka, Japan.

Diagnosis of post-stroke epilepsy is often challenging because of a low incidence of epileptiform abnormalities on electroencephalography (EEG). Hence, this study evaluated whether postictal subtraction single-photon emission computed tomography (SPECT) could visualize epileptic activity and act as a diagnostic modality in post-stroke epilepsy. Fifty post-stroke epilepsy patients, who had undergone Tc-99m-ECD SPECT twice (postictal and interictal), were enrolled. The postictal hyperperfusion area was identified by subtraction (postictal-interictal) SPECT and classified into two distribution types: superficial or deep-seated. Laterality and distribution of postictal hyperperfusion on subtraction SPECT were compared with stroke lesions, seizure symptoms, and epileptiform EEG findings. Forty-three of the 50 patients (86%) had hyperperfusion on subtraction SPECT and 26 (52%) had epileptiform EEG findings. Subtraction SPECT showed prolonged postictal hyperperfusion despite the relatively long interval between seizure end and postictal SPECT (median: 19.1 h, range: 2.2-112.5 h). The laterality of the hyperperfusion area had a high concordance rate with the laterality of stroke lesions (97.7%), seizure symptoms (91.9%), and epileptiform EEG findings (100%). Scalp EEG identified epileptiform activity more frequently in superficial type of SPECT, but less frequently in deep-seated type (both,  = 0.03). Postictal SPECT can be complementary to scalp EEG in endorsing the diagnosis and location of post-stroke epilepsy.
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http://dx.doi.org/10.1177/0271678X20902742DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7747161PMC
January 2021

Active direct current (DC) shifts and "Red slow": two new concepts for seizure mechanisms and identification of the epileptogenic zone.

Neurosci Res 2020 Jul 8;156:95-101. Epub 2020 Feb 8.

Department of Neurology, Kyoto University Graduate School of Medicine, Japan.

An accurate identification of the epileptogenic zone is essential for patients with intractable epilepsy who are candidates to neurosurgery. EEG recordings can provide predictive biomarkers of the epileptogenic zone. Wide-band EEG makes it possible to record from infraslow (including DC shifts) to high frequency (HFO, over 300 Hz) oscillations for diagnostic purposes in patients with epilepsy. Although the presence of HFOs have been proposed to sign the epileptogenic zone, DC-like recordings demonstrate that DC shifts precede HFOs at seizure onset. This led to the proposal that "ictal active DC shifts" are causally related to seizure onset as opposed to "ictal passive DC shifts". Thus, active DC shifts may constitute predictive biomarkers of the epileptogenic zone in epilepsy. Since DC shift is commonly associated to a rise in extracellular potassium, potassium homeostasis regulated by Kir4.1 channels in astrocytes may play an key role at seizure onset. In addition, we hypothesize that, during the interictal period, the co-occurrence of slow events and interictal HFOs, so-called "Red slow", may also delineate an epileptogenic zone, even if a seizure would not be actually recorded.
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http://dx.doi.org/10.1016/j.neures.2020.01.014DOI Listing
July 2020

[Electrophysiological evidence of impaired neuromuscular junction in a case of phosphoglucomutase 1 deficiency manifesting fluctuating muscle weakness].

Rinsho Shinkeigaku 2020 Feb 19;60(2):152-156. Epub 2020 Jan 19.

Division of Neurology, Kobe University Graduate School of Medicine.

A 27 year-old Canadian man suffered from fluctuating muscle weakness in the past several years. The patient had a past history of intestinal bleeding, bifid uvula and hypothyroidism in his childhood. Repetitive nerve stimulation tests showed a decrement pattern in the left deltoid muscle. The single fiber electromyography of the left extensor digitorum muscle showed an increment of jitter. Both findings were improved by the edrophonium test. He was diagnosed as having phosphoglucomutase 1 (PGM1) deficiency, as the compound heterozygote mutation of the PGM1 gene was recognized in the whole-exome sequencing and the enzyme activity of PGM1 was defective in the biopsied muscle. Treatment with the galactose lead to improvement of the fluctuating muscle weakness and decremental pattern in the repetitive stimulation test. PGM1 deficiency should be listed in the differential diagnosis of the neuromuscular junction disorder, when the patient is seronegative for antibodies related with myasthenia gravis and shows symptoms or signs consistent with PGM1 deficiency.
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http://dx.doi.org/10.5692/clinicalneurol.cn-001375DOI Listing
February 2020

Mathematical structures for epilepsy: High-frequency oscillation and interictal epileptic slow (red slow).

Neurosci Res 2020 Jul 20;156:178-187. Epub 2019 Nov 20.

Department of Epilepsy, Movement Disorder and Physiology, Kyoto University, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan.

In the present study, we attempted to characterize two characteristic features within the dynamic behavior of wideband electrocorticography data, which were recorded as the brain waves of epilepsy, comprising high-frequency oscillations (HFOs) and interictal epileptic slow (red slow). The results of power spectrum and nonlinear time series analysis indicate that, on one hand, HFOs at epileptic focus are characterized by one-dimensional dynamical systems in ictal onset time segments at an epileptic focus for two patients' datasets; on the other hand, an interictal epileptic slow is characterized by the residue of power spectrum. The results suggest that the degree of freedom of the brain dynamics during epileptic seizure with HFO degenerates to low-dimensional dynamics; hence, the interictal epileptic slow as the precursors of the seizure onset can be detected simply from interictal brain wave data for the dataset of one patient. Therefore, our results are essential to understand the brain dynamics in epilepsy.
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http://dx.doi.org/10.1016/j.neures.2019.11.008DOI Listing
July 2020

A score to map the lateral nonprimary motor area: Multispectrum intrinsic brain activity versus cortical stimulation.

Epilepsia 2019 11 15;60(11):2294-2305. Epub 2019 Oct 15.

Department of Epilepsy, Movement Disorders, and Physiology, Kyoto University Graduate School of Medicine, Kyoto, Japan.

Objective: Multispectrum electrocorticographic components are critical for mapping the nonprimary motor area (NPMA). The objective of this study was to derive and validate a reliable scoring system for electrocorticography-based NPMA mapping (NPMA score) to replace electrical cortical stimulation (ECS) during brain surgery.

Methods: We analyzed 14 consecutive epilepsy patients with subdural electrodes implanted in the frontal lobe at Kyoto University Hospital. The NPMA score was retrospectively derived from multivariate analysis in the derivation group (patients = 7, electrodes = 713, during 2010-2013) and validated in the validation group (patients = 7, electrodes = 772, during 2014-2017). We assessed the accuracy and reliability of the score relative to ECS in determining the NPMA and predicting postoperative functional outcomes.

Results: Multivariate analysis in the derivation group led to an 8-point score for predicting ECS-based NPMA (1 point for anatomical localization of the electrode and 1 or 2 points for movement-related electrocorticographic components regardless of somatotopy in very slow cortical potential shifts [<0.5 Hz], 40-80-Hz band power increase, and 8-24-Hz band power decrease), which was validated in the validation group. The area under the receiver operating characteristic curve (AUC) was 0.89 in the derivation group. Good prediction (specificity = 94%, sensitivity = 100%) and discrimination (AUC = 0.87) were reproduced in the validation group. Overall, higher NPMA scores identified 2 patients with postoperative deficits after frontal lobe resection.

Significance: The NPMA score is reliable for NPMA mapping, potentially replacing ECS. It is a potential prognostic marker for postoperative functional deficits.
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http://dx.doi.org/10.1111/epi.16367DOI Listing
November 2019

Plasmablasts and neuroimmunological disorders.

Immunol Med 2019 Sep 29;42(3):103-107. Epub 2019 Aug 29.

Department of Immunology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan.

Neuroimmunological disorders are diseases of the nervous system, wherein the immune system contributes to tissue injury and repair. Autoantibodies are useful biomarkers for the diagnosis of neuroimmunological disorders and evaluating disease activity. Emerging evidence indicates that several autoantibodies are associated with neuroimmunological diseases. While the differential diagnostic process based on the positivity of autoantibodies has been established, the mechanisms underlying the production of these autoantibodies still need to be investigated. Autoantibodies are not necessarily pathogenic, and some are involved in immune regulation. Autoantibody-producing plasmablasts are involved in both pathogenicity and immune regulation of diseases. Thus, comparisons between these pathogenic and regulatory plasmablasts may give us clues understanding the machinery of autoantibody-related neuroimmunological diseases. Moreover, elucidating these mechanisms may allow the development of new immune-modulatory therapies to facilitate regulatory B cell function in neuroimmunological diseases. To this end, herein the roles of plasmablasts in neuroimmunological disorders are discussed.
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http://dx.doi.org/10.1080/25785826.2019.1659476DOI Listing
September 2019

Validation of the Guy's Neurological Disability Scale as a screening tool for cognitive impairment in multiple sclerosis.

Mult Scler Relat Disord 2019 Oct 12;35:272-275. Epub 2019 Aug 12.

Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan.

Objectives: Cognitive impairment is a common symptom affecting daily activities of the patients with multiple sclerosis (MS). Various cognitive evaluation tests are available, yet most of them are complex and time-consuming to perform in outpatient clinics. In this study, we aimed to validate a Japanese version of the Guy's Neurological Disability Scale (GNDS) as a user-friendly tool to evaluate comprehensive disabilities in MS including cognitive function.

Methods: Questions of the GNDS were translated into Japanese and named GNDS-J. Forty-four patients were examined by the Expanded Disability Status Scale (EDSS), the Paced Auditory Serial Addition Test (PASAT), the Symbol Digit Modalities Test (SDMT), the vitality scale, and the GNDS-J in the same time at remission state.

Results: The GNDS-J scores correlated with the EDSS scores(r = 0.61), and inversely correlated with the PASAT2/1(r=-0.56/-0.49) scores and the SDMT scores (r=-0.68), whereas the GNDS-J did not show any correlation with the vitality scale. Furthermore, eleven patients were evaluated over 5 years for changes in these scores. Eight out of 11 patients had exacerbated GNDS, and all of these patients experienced clinical relapse during this period.

Conclusion: The GNDS-J is a valid tool to perform in outpatient clinics, which could provide a comprehensive scale for evaluating symptoms of MS, thus the disease activity by repeated measure.
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http://dx.doi.org/10.1016/j.msard.2019.08.012DOI Listing
October 2019

Low-dose perampanel improves refractory cortical myoclonus by the dispersed and suppressed paroxysmal depolarization shifts in the sensorimotor cortex.

Clin Neurophysiol 2019 10 19;130(10):1804-1812. Epub 2019 Jul 19.

Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, Japan. Electronic address:

Objective: To elucidate the effects of perampanel (PER) on refractory cortical myoclonus for dose, etiology and somatosensory-evoked potential (SEP) findings.

Methods: We examined 18 epilepsy patients with seizure and cortical myoclonus. Based on data accumulated before and after PER treatment, correlations among clinical scores in myoclonus and activities of daily life (ADL); early cortical components of SEP; and PER blood concentration, were analyzed.

Results: PER (mean dose: 3.2 ± 2.1 mg/day) significantly improved seizures, myoclonus and ADL and significantly decreased the amplitude of and prolonged latency of giant SEP components. The degree of P25 and N33 prolongations (23.8 ± 1.6 to 24.7 ± 1.7 ms and 32.1 ± 4.0 to 33.7 ± 3.4 ms) were significantly correlated with improved ADL score (p = 0.019 and p = 0.025) and blood PER concentration (p = 0.011 and p = 0.025), respectively.

Conclusions: Low-dose PER markedly improved myoclonus and ADL in patients with refractory cortical myoclonus. Our results suggest that SEP, particularly P25 latency, can be used as a potential biomarker for assessing the objective effects of PER on intractable cortical myoclonus.

Significance: In this study, PER lessened the degree of synchronized discharges in the postsynaptic neurons in the primary motor cortex.
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http://dx.doi.org/10.1016/j.clinph.2019.07.006DOI Listing
October 2019

Human entorhinal cortex electrical stimulation evoked short-latency potentials in the broad neocortical regions: Evidence from cortico-cortical evoked potential recordings.

Brain Behav 2019 09 30;9(9):e01366. Epub 2019 Jul 30.

Department of Epilepsy, Movement Disorders and Physiology, Kyoto University, Kyoto, Japan.

Objective: We aimed at clarifying the clinical significance of the responses evoked by human entorhinal cortex (EC) electrical stimulation by means of cortico-cortical evoked potentials (CCEPs).

Methods: We enrolled nine patients with medically intractable medial temporal lobe epilepsy who underwent invasive presurgical evaluations with subdural or depth electrodes. Single-pulse electrical stimulation was delivered to the EC and fusiform gyrus (FG), and their evoked potentials were compared. The correlation between the evoked potentials and Wechsler Memory Scale-Revised (WMS-R) score was analyzed to investigate whether memory circuit was involved in the generation of the evoked potentials.

Results: In most electrodes placed on the neocortex, EC stimulation induced unique evoked potentials with positive polarity, termed as "widespread P1" (P1w). Compared with FG stimulation, P1w induced by EC stimulation were distinguished by their high occurrence rate, short peak latency (mean: 20.1 ms), small peak amplitude, and waveform uniformity among different recording sites. A stimulation of more posterior parts of the EC induced P1w with shorter latency and larger amplitude. P1w peak amplitude had a positive correlation (r = .69) with the visual memory score of the WMS-R. In one patient, with depth electrode implanted into the hippocampus, the giant evoked potentials were recorded in the electrodes of the anterior hippocampus and EC near the stimulus site.

Conclusions: The human EC electrical stimulation evoked the short-latency potentials in the broad neocortical regions. The origin of P1w remains unclear, although the limited evidence suggests that P1w is the far-field potential by the volume conduction of giant evoked potential from the EC itself and hippocampus. The significance of the present study is that those evoked potentials may be a potential biomarker of memory impairment in various neurological diseases, and we provided direct evidence for the functional subdivisions along the anterior-posterior axis in the human EC.
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http://dx.doi.org/10.1002/brb3.1366DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6749511PMC
September 2019

[Increased disease activity in a case of multiple sclerosis after switching treatment from fingolimod to natalizumab].

Rinsho Shinkeigaku 2019 Aug 23;59(8):536-540. Epub 2019 Jul 23.

Division of Neurology, Kobe University Graduate School of Medicine.

A 42-year-old woman diagnosed with multiple sclerosis (MS) at the age of 37 was initially treated with interferon-β IM. The frequency of clinical relapses was twice in 4 years. At the age of 41, due to difficulty in administering muscle injections, an oral medication fingolimod was started. However, it was discontinued after a month due to decreased lymphocyte count, following which natalizumab was administered. The number of relapses increased 3 times in eleven months, and the number of T lesions on the MRI increased from 12 to 23. Natalizumab was discontinued because the test for the anti-natalizumab antibody was positive. It was suspected that both, the rebound syndrome caused by fingolimod cessation and the drug neutralization by anti-natalizumab antibodies, were associated with the exacerbation of disease activity. Thus, careful attention should be paid to potential occurrence of these events post switching between disease-modifying drugs for treating MS with high activity.
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http://dx.doi.org/10.5692/clinicalneurol.cn-001307DOI Listing
August 2019

Hashimoto's Encephalopathy Presenting with Smoldering Limbic Encephalitis.

Intern Med 2019 15;58(8):1167-1172. Epub 2019 Apr 15.

Department of Neurology, Kyoto University Graduate School of Medicine, Japan.

Hashimoto's encephalopathy (HE) is a steroid-responsive autoimmune encephalopathy associated with Hashimoto thyroiditis. We herein report a case of HE manifesting "smoldering" limbic encephalitis with persisting symptoms and abnormalities on examinations. Although our patient experienced partial clinical remission after treatment, hippocampal hypermetabolism on [F] fluorodeoxyglucose positron emission tomography (FDG-PET) and subclinical seizures on video electroencephalography persisted. Hypermetabolism on FDG-PET was improved by additional prednisolone therapy. Thus, as with other autoimmune limbic encephalitis cases, HE can take a course of "smoldering" encephalitis. FDG-PET and electroencephalogram findings can reflect the disease activity degree in such patients, although with certain neurophysiological and biochemical distinctions.
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http://dx.doi.org/10.2169/internalmedicine.1289-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6522399PMC
June 2019