[Show abstract][Hide abstract] ABSTRACT: Central pontine myelinolysis (CPM), which was originally considered to be the result of rapid correction of chronic hyponatremia, is not necessarily accompanied by hyponatremia or drastic changes in serum sodium level. Here, we report a case of an anorexic 55-year-old male with a history of pharyngo-laryngo-esophagogastrectomy, initially hospitalized with status epilepticus. Although his consciousness gradually recovered as we were controlling his convulsion, it deteriorated again with new onset of anisocoria, and magnetic resonance imaging (MRI) at this point revealed CPM. Rapid change of serum sodium or osmolarity, which is often associated with CPM, had not been apparent throughout his hospitalization. Instead, a review of the serum biochemistry test results showed that serum phosphate had drastically declined the day before the MRI first detected CPM. In this case, we suspect that hypophosphatemia induced by refeeding syndrome greatly contributed to the occurrence of CPM.
Case Reports in Neurology 10/2015; 7(3):196-203. DOI:10.1159/000440711
[Show abstract][Hide abstract] ABSTRACT: The hippocampus is well known to be involved in memory, as well as in perceptual processing. To date, the electrophysiological process by which unilateral hippocampal lesions, such as hippocampal sclerosis (HS), modulate the auditory processing remains unknown. Auditory-evoked magnetic fields (AEFs) are valuable for evaluating auditory functions, because M100, a major component of AEFs, originates from auditory areas. Therefore, AEFs of mesial temporal lobe epilepsy (mTLE, n=17) with unilateral HS were compared with those of healthy (HC, n=17) and disease controls (n=9), thereby determining whether AEFs were indicative of hippocampal influences on the auditory processing. Monaural tone-burst stimuli were presented for each side, followed by analysis of M100 and a previously less characterized exogenous component (M400: 300-500 ms). The frequency of acceptable M100 dipoles was significantly decreased in the HS side. Beam-forming-based source localization analysis also showed decreased activity of the auditory area, which corresponded to the inadequately estimated dipoles. M400 was found to be related to the medial temporal structure on the HS side. Volumetric analysis was also performed, focusing on the auditory-related areas (planum temporale, Heschl's gyrus, and superior temporal gyrus), as well as the hippocampus. M100 amplitudes positively correlated with hippocampal and planum temporale volumes in the HC group, whereas they negatively correlated with Heschl's gyrus volume in the mTLE group. Interestingly, significantly enhanced M400 component was observed in the HS side of the mTLE patients. In addition, the M400 component positively correlated with Heschl's gyrus volume and tended to positively correlate with disease duration. M400 was markedly diminished after hippocampal resection. Although volumetric analysis showed decreased hippocampal volume in the HS side, the planum temporale and Heschl's gyrus, the two major sources of M100, were preserved. These results suggested that HS significantly influenced AEFs. Therefore, we concluded that the hippocampus modulates auditory processing differently under normal conditions and in HS.
[Show abstract][Hide abstract] ABSTRACT: Although the epileptogenic location of dysembryoplastic neuroepithelial tumors (DNTs) is controversial, it has recently been thought to be located within cortical dysplasia (CD) due to its frequent association with CD. Among the 84 resection surgeries for intractable epilepsy performed in our institution between January 2003 and April 2010, three patients had epileptogenic DNTs. In two cases, chronic subdural electrocorticography (ECoG) was performed, and the ictal onset zone was revealed to be in the cortex around the DNT. The ictal onset zone was resected along with the DNT, and good seizure outcome was achieved. Although histological examination of the ictal onset zone revealed mild gliosis, coexistence of CD was not noted. In the third case, the DNT was located in the left lateral temporal lobe and the intraoperative ECoG revealed frequent paroxysmal activity in the medial temporal lobe. Resection of the lateral temporal lobe involving the tumor did not result in good seizure control. The optimal surgical treatment of DNT is controversial. Some authors consider lesionectomy to be sufficient for good seizure control, whereas others advocate that additional resection of the epileptogenic zone beside the tumor improves outcome. Because the epileptogenic location of DNT varies among cases, it is important to identify its location by preoperative multimodal examinations, including chronic subdural ECoG recordings. (Received February 16, 2012; Accepted September 30, 2014; Published April 1 2015).
Brain and nerve = Shinkei kenkyū no shinpo 04/2015; 67(4):525-32. DOI:10.11477/mf.1416200170
[Show abstract][Hide abstract] ABSTRACT: Vagal nerve stimulation(VNS)is an effective adjunctive therapy for medically intractable epilepsy. However, VNS is a palliative therapy, and craniotomy should preferably be performed when complete seizure remission can be expected after craniotomy. We report here three patients who were referred for VNS therapy, but underwent craniotomy instead of VNS based on the results of a comprehensive preoperative evaluation, and achieved good seizure control. Case 1 was a 48-year-old woman with left temporal lobe epilepsy and amygdalar enlargement. Even though no left hippocampal sclerosis was observed on magnetic resonance imaging, she underwent left anterior temporal lobectomy and hippocampectomy. Case 2 was a 36-year-old woman with multiple bilateral subependymal nodular heterotopias, who underwent resection of the left medial temporal lobe including subependymal nodular heterotopias adjacent to the left inferior horn. Case 3 was a 25-year-old man with posttraumatic epilepsy. As the right hemisphere was most affected, multiple subpial transections were performed on the left frontal convexity. These three patients were referred to us for VNS therapy because there was a dissociation between the interictal electroencephalogram and magnetic resonance imaging findings, or because they had multiple or extensive epileptogenic lesions. Comprehensive preoperative evaluation including ictal electroencephalography can help to identify patients who are suitable candidates for craniotomy.
No shinkei geka. Neurological surgery 12/2014; 42(12):1137-46. DOI:10.11477/mf.1436200049 · 0.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: "Solitary" meningioangiomatosis (MA) is a rare, benign, hamartomatous lesion of the cerebral cortex and frequently leads to epilepsy. However, the source of the epileptogenicity in meningioangiomatosis remains controversial. We report two surgically-treated meningioangiomatosis cases with medically intractable epilepsy. In both cases, chronic subdural electrocorticogram (ECoG) recordings identified the ictal onset zone on apparently normal cortex, adjacent to and/or above the meningioangiomatosis lesion, not on the meningioangiomatosis lesion itself. The ictal onset zone was resected, along with the MA lesion, and good seizure outcome was achieved. Histological examination of the ictal onset zone revealed the presence of ILAE focal cortical dysplasia (FCD) type IIIc. Our case studies suggest that in the surgical management of epilepsy with meningioangiomatosis, it is important to identify undetected, but epileptogenic, ILAE FCD Type IIIc, using preoperative multimodal examinations, including chronic ECoG recordings.
Epileptic disorders: international epilepsy journal with videotape 11/2014; 16(4). DOI:10.1684/epd.2014.0695 · 0.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Recent resting-state functional MRI (rs-fMRI) studies have demonstrated that the human brain is composed of several essential large-scale functional brain networks, including the "default-mode network". We analyzed electrocorticogram data from four patients with intractable focal epilepsy and compared the extent of these large-scale functional brain networks with propagation pathways of ictal discharge. We found that large-scale functional brain networks had markedly similar spatial patterns compared with multisite ictal fast activity, suggesting that some epileptic activity propagates along large-scale functional brain networks. Given that decreased functional connectivity in large-scale functional brain networks has been reported in patients with focal epilepsy, ictal propagation may lead to chronic alteration of normal functional networks in the brain.
[Show abstract][Hide abstract] ABSTRACT: Focal cortical dysplasia (FCD) is an important cause of intractable epilepsy. Previous rat studies have utilized freeze lesioning of neonatal animals to model FCD; however, such models are unable to demonstrate spontaneous seizures without seizure-provoking events. Therefore, we created an animal model with multiple FCD, produced during embryonic development, and observed whether spontaneous seizures occurred. Furthermore, we examined the relationship between FCD and epileptogenesis using immunohistochemistry. At 18 days postconception, a frozen metal probe was placed bilaterally on the scalps of Sprague-Dawley rat embryos through the uterus wall to produce multiple FCD. Eleven of 16 rats showed spontaneous seizures arising in the hippocampus from postnatal day47. Movement cessation followed by sniffing and mastication, culminating in wet-dog shaking, was seen during the hippocampal EEG discharges. Alterations in the levels of glutamatergic and GABA-ergic receptors were investigated during growth. We created an animal model showing spontaneous seizures without a provoking event except for the existence of cortical dysplasia, and without a genetic or general systematic cause like MAM injection or irradiation. The seizures resembled human temporal lobe epilepsy both clinically and on EEG. This model should enable better clarification of the mechanisms underlying the development of human epilepsy.
[Show abstract][Hide abstract] ABSTRACT: The sensory projections from the oral cavity, pharynx, and larynx are crucial in assuring safe deglutition, coughing, breathing, and voice production/speaking. Although several studies using neuroimaging techniques have demonstrated cortical activation related to pharyngeal and laryngeal functions, little is known regarding sensory projections from the laryngeal area to the somatosensory cortex. The purpose of this study was to establish the cortical activity evoked by somatic air-puff stimulation at the laryngeal mucosa using magnetoencephalography. Twelve healthy volunteers were trained to inhibit swallowing in response to air stimuli delivered to the larynx. Minimum norm estimates was performed on the laryngeal somatosensory evoked fields (LSEFs) to best differentiate the target activations from non-task-related activations. Evoked magnetic fields were recorded with acceptable reproducibility in the left hemisphere, with a peak latency of approximately 100ms in 10 subjects. Peak activation was estimated at the caudolateral region of the primary somatosensory area (S1). These results establish the ability to detect LSEFs with an acceptable reproducibility within a single subject and among subjects. These results also suggest the existence of laryngeal somatic afferent input to the caudolateral region of S1 in human. Our findings indicate that further investigation in this area is needed, and should focus on laryngeal lateralization, swallowing, and speech processing.
[Show abstract][Hide abstract] ABSTRACT: Age-related changes are well documented in the primary somatosensory cortex (SI). Based on previous somatosensory evoked potential studies, the amplitude of N20 typically increases with age probably due to cortical disinhibition. However, less is known about age-related change in the secondary somatosensory cortex (SII). The current study quantified age-related changes across SI and SII mainly based on oscillatory activity indices measured with magnetoencephalography.
We recorded somatosensory evoked magnetic fields (SEFs) to right median nerve stimulation in healthy young and old subjects and assessed major SEF components. Then, we evaluated the phase-locking factor (PLF) for local field synchrony on neural oscillations and the weighted phase-lag index (wPLI) for cortico-cortical synchrony between SI and SII.
PLF was significantly increased in SI along with the increased amplitude of N20m in the old subjects. PLF was also increased in SII associated with a shortened peak latency of SEFs. wPLI analysis revealed the increased coherent activity between SI and SII.
Our results suggest that the functional coupling between SI and SII is influenced by the cortical disinhibition due to normal aging.
We provide the first electrophysiological evidence for age-related changes in oscillatory neural activities across the somatosensory areas.
Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 11/2013; 125(5). DOI:10.1016/j.clinph.2013.10.005 · 3.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report a case of a 22-year-old male who was transferred to our hospital in a comatose state following successive seizures. Low blood glucose had been detected upon his arrival at the previous hospital. He became responsive 12days after the onset of coma. Upon regaining consciousness he exhibited severe dysarthria and several interhemispheric disconnection signs such as intermanual conflict, left-hand dysgraphia, left hemispatial neglect confined to the right hand, impaired interhemispheric transfer, and unilateral constructional apraxia of the right hand. Brain MRI disclosed T2-weighted and diffusion-weighted hyperintense lesions with reduced apparent diffusion coefficients in the bilateral centrum semiovale, splenium of the corpus callosum, right posterior limb of the internal capsule, and bilateral middle cerebellar peduncles. As the MRI findings vanished, his interhemispheric disconnection signs gradually resolved. Abdominal imaging studies revealed a pancreatic tumor, which was later endocrinologically diagnosed as an insulinoma. This is an extremely rare report of interhemispheric disconnection signs due to hypoglycemic encephalopathy. The lesions in the bilateral centrum semiovale likely contributed to the interhemispheric disconnection signs.
Journal of the neurological sciences 09/2013; 335(1-2). DOI:10.1016/j.jns.2013.09.025 · 2.47 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objectives
To clarify the differences in multimodality evoked potential findings between patients with atopic myelitis (AM) and those with multiple sclerosis (MS). MethodsA retrospective chart review of 70 consecutive AM patients and 93 MS patients was carried out. All patients were negative for serum anti-aquaporin-4 antibody. Visual- (VEP), somatosensory- (SEP) and motor-evoked potentials (MEP) recorded at first examination, and magnetic resonance imaging (MRI) findings from the first examination were compared between AM and MS patients. ResultsCompared with MS patients, AM patients showed male preponderance, lower the Expanded Disability Status Scale scores and less frequent spinal cord MRI lesions. Visual impairment and muscle weakness were also less severe in AM patients. Frequencies of abnormal VEP and prolonged central conduction time on lower limb MEP were significantly lower in AM patients than in MS patients (AM vs MS: 9.5% vs 55.6%, and 28.2% vs 54.4%, respectively), whereas frequencies of peripheral nerve involvement in upper and lower limb MEP and upper limb SEP were significantly higher in AM than in MS patients (AM vs MS: 12.8% vs 2.9%, 17.9% vs 2.9% and 33.3% vs 4.4%, respectively). When patients whose EP were examined within 5 years of disease onset were compared, lower frequencies of abnormal VEP and higher peripheral nerve involvement detected by MEP and SEP were observed in AM patients. ConclusionsAM patients have distinct physiological features compared with MS patients, even at the first examination of evoked potentials, which might suggest distinct immunological mechanisms between the two conditions. Multimodality evoked potentials might contribute to the early discrimination of these two disorders.
Clinical and Experimental Neuroimmunology 06/2013; 4(1). DOI:10.1111/cen3.12018
[Show abstract][Hide abstract] ABSTRACT: Focal cortical dysplasia (FCD) is an important cause of intractable epilepsy. Previous rat studies have utilized freeze lesioning of neonatal animals to model FCD; however, such models are unable to demonstrate spontaneous seizures without seizure-provoking events. Therefore, we created an animal model with multiple FCD, produced during embryonic development, and observed whether spontaneous seizures occurred. Furthermore, we examined the relationship between FCD and epileptogenesis using immunohistochemistry.
Epilepsy research 04/2013; 105(3). DOI:10.1016/j.eplepsyres.2013.03.003 · 2.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The analysis of epileptic discharges in magnetoencephalography with minimum norm estimates (MNE) is expected to provide more precise localization of epileptic discharges compared with electroencephalographic estimations. However, the clinical feasibility of MNE remains unclear. In this study, we aimed to elucidate the onset and propagation patterns of interictal spikes using MNE. Seven patients with intractable epilepsy whose epileptogenicity was assumed to exist in the convexity of the cerebral cortex were studied. For MNE and electrocorticography (ECoG), we characterized the propagation patterns of interictal epileptic discharges according to the area in which they originated and where they extended; we then examined whether the propagation patterns observed in MNE were identified by ECoG. We also examined the relationship between the positions of spikes estimated by the equivalent current dipole (ECD) method and MNE. Among the seven patients, nine propagation patterns of epileptic discharges were observed by MNE, all of which were also identified by ECoG. In seven patterns, the epileptic activity propagated around the initial portion. However, in two patterns, the center of activities moved according to propagation with maintained activity of the initial portion. The locations of spikes identified by the ECD method were within the areas estimated by MNE when the epileptic activity propagated. However, the ECD method failed to detect onset activities identified by MNE in three of nine patterns. Thus, MNE is more useful as a means of presurgical evaluation for epilepsy than the ECD method because it can delineate the onset of epileptic activities as shown in ECoG.
[Show abstract][Hide abstract] ABSTRACT: Although there is no universally accepted definition, traumatic medial temporal lobe ep-ilepsy (traumatic MTLE) can be generally de-fined as a type of post-traumatic epilepsy with medial temporal epileptogenicity. Previous studies have demonstrated that patients with traumatic MTLE frequently have hippocampal sclerosis (HS) coexisting with traumatic neo-cortical lesions. We report a 39-year-old MTLE patient with a subcortical lesion in the internal capsule, suspected to be caused by mild diffuse axonal injury. The results of pre-surgical examinations and intraoperative elec-trocorticograms were consistent with a diag-nosis of MTLE. Therefore, an anterior tem-poral lobectomy with hippocampectomy was performed. A 3D short tau inversion recovery 3-Tesla MRI scan clearly depicted possibly Wallerian degeneration in the temporal stem, which was continuous with the subcortical
[Show abstract][Hide abstract] ABSTRACT: Patients with epilepsy are at high risk for major depression relative to the general population, and both disorders are associated with changes in adult hippocampal neurogenesis, although the mechanisms underlying disease onset remain unknown. The expression of fosB, an immediate early gene encoding FosB and ΔFosB/Δ2ΔFosB by alternative splicing and translation initiation, is known to be induced in neural progenitor cells within the subventricular zone of the lateral ventricles and subgranular zone of the hippocampus, following transient forebrain ischemia in the rat brain. Moreover, adenovirus-mediated expression of fosB gene products can promote neural stem cell proliferation. We recently found that fosB-null mice show increased depressive behavior, suggesting impaired neurogenesis in fosB-null mice. In the current study, we analyzed neurogenesis in the hippocampal dentate gyrus of fosB-null and fosB(d/d) mice that express ΔFosB/Δ2ΔFosB but not FosB, in comparison with wild-type mice, alongside neuropathology, behaviors and gene expression profiles. fosB-null but not fosB(d/d) mice displayed impaired neurogenesis in the adult hippocampus and spontaneous epilepsy. Microarray analysis revealed that genes related to neurogenesis, depression, and epilepsy were altered in the hippocampus of fosB-null mice. Thus, we conclude that the fosB-null mouse is the first animal model to provide a genetic and molecular basis for the comorbidity between depression and epilepsy with abnormal neurogenesis, all of which are caused by loss of a single gene, fosB.Neuropsychopharmacology accepted article preview online, 18 December 2012; doi:10.1038/npp.2012.260.
Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology 12/2012; 38(5). DOI:10.1038/npp.2012.260 · 7.05 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Electrical brain stimulation is used in a variety of clinical situations, including cortical mapping for epilepsy surgery, cortical stimulation therapy to terminate seizure activity in the cortex, and in deep brain stimulation therapy. However, the effects of stimulus parameters are not fully understood. In this study, we systematically tested the impact of various stimulation parameters on the generation of motor symptoms and afterdischarges (ADs). Focal electrical stimulation was delivered at subdural cortical, intracortical, and hippocampal sites in a rat model. The effects of stimulus parameter on the generation of motor symptoms and on the occurrence of ADs were examined. The effect of stimulus irregularity was tested using random or regular 50Hz stimulation through subdural electrodes. Hippocampal stimulation produced ADs at lower thresholds than neocortical stimulation. Hippocampal stimulation also produced significantly longer ADs. Both in hippocampal and cortical stimulation, when the total current was kept constant with changing pulse width, the threshold for motor symptom or AD was lowest between 50 and 100Hz and higher at both low and high frequencies. However, if the pulse width was fixed, the threshold did not increase above 100Hz and it apparently continued to decrease through 800Hz even if the difference did not reach statistical significance. There was no significant difference between random and regular stimulation. Overall, these results indicate that electrode location and several stimulus parameters including frequency, pulse width, and total electricity are important in electrical stimulation to produce motor symptoms and ADs.
Epilepsy research 11/2012; 104(1). DOI:10.1016/j.eplepsyres.2012.10.002 · 2.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Parainfectious or autoimmune striatal lesions have been repeatedly described in children. We report a 7-year-old girl with painful muscle spasms, leading to the diagnosis of childhood stiff-person syndrome (SPS). Striatal lesions were demonstrated by diffusion-weighted magnetic resonance imaging (MRI) and single-photon emission computed tomography but not by conventional MRI. Autoantibodies against glutamic acid decarboxylase (GAD) were absent. Steroid pulse therapy and high-dose intravenous immunoglobulin resolved all the symptoms with slight sequelae. Childhood SPS may be characterized by absent anti-GAD antibodies and a transient benign clinical course, and it may have a pathomechanism distinct from that in adult SPS.
Brain & development 08/2012; 35(6). DOI:10.1016/j.braindev.2012.08.003 · 1.88 Impact Factor