[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; · 3.12 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; · 2.32 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).
[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. Electroencephalogram (EEG) and video recording were performed from postnatal day (P) 35 to P77. Brain tissues were examined immunohistochemically at P28 and P78 using semiquantitative densitometry. Eleven of 16 rats (68.8%) showed spontaneous seizures arising in the hippocampus from P47. Movement cessation followed by sniffing and mastication, culminating in wet-dog shaking, was seen during the hippocampal EEG discharges. FCD was observed in the bilateral frontoparietal lobes. The expression levels of N-methyl-d-aspartate receptor (NMDAR) subunits 1, 2A, 2B, the glutamate/aspartate transporter and the glial glutamate transporter 1 (GLT1) at FCD sites were increased at P28 and P78. There were no major histological abnormalities in the hippocampi compared with those in the cortex. However, the expression levels of NMDAR 2A and 2B were increased at P28. Levels of NMDAR1, 2A and 2B, the glutamate/aspartate transporter and GLT1 were also increased at P78. 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. Alterations in the levels of glutamatergic and GABAergic receptors were investigated during growth. This model should enable better clarification of the mechanisms underlying the development of human epilepsy.
[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: 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: 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; · 8.68 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.
[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.
[Show abstract][Hide abstract] ABSTRACT: To establish the first evidence-based diagnostic criteria for atopic myelitis (AM) enabling it to be discriminated from myelitis-onset multiple sclerosis (MS), which is a difficult differential diagnosis.
Sixty-nine consecutive AM patients examined from 1996 to 2010 at Kyushu University hospital, who fulfilled the empirical definition of AM (2003), and 51 myelitis-onset MS patients in whom allergen-specific IgE was measured, were enrolled. The first available brain MRI findings were compared between the two. Then, we compared the clinical and laboratory features between the 16 AM cases who did not meet the Barkhof brain MRI criteria for MS after more than 5 years follow-up and 51 myelitis-onset MS cases. Based on the discriminative findings, we established diagnostic criteria for AM and calculated the sensitivity and specificity.
AM patients had a significantly lower frequency of Barkhof brain lesions on baseline MRI than myelitis-onset MS patients. AM patients had a significantly higher frequency of present and/or past history of atopic disease and hyperIgEemia, and higher cerebrospinal fluid levels of interleukin 9 and CCL11/eotaxin, but a lower frequency of oligoclonal IgG bands than myelitis-onset MS patients. Our proposed diagnostic criteria for AM demonstrated 93.3% sensitivity and 93.3% specificity for AM against myelitis-onset MS, with 82.4% positive predictive value and 97.7% negative predictive value.
Our first evidence-based criteria for AM show high sensitivity and specificity, and would be useful clinically.
Journal of the neurological sciences 02/2012; 316(1-2):30-5. · 2.32 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Age-related electrophysiological changes in the primary somatosensory cortex (SI) are well known. There is evidence that the amplitude of the N20 component of median nerve somatosensory evoked potentials typically increases with age, probably because of cortical disinhibition. The secondary somatosensory cortex (SII) receives dual input from the SI and the thalamus. We quantified age-related changes both in SI and SII using magnetoencephalography (MEG). We recorded somatosensory evoked magnetic fields (SEFs) to median nerve stimulation in 15 young adults (aged 22-36 years, mean age 29.0±4.1) and 15 older adults (aged 52-67 years, mean age 61.9±5.4), and analysed major SEF components in SI and SII. The amplitude and equivalent current dipole (ECD) strength of the N20m were significantly increased in the older adults, consistent with the well-known electrophysiological change for cortical disinhibition in SI. The latency of N20m showed a trend for increase in older subjects, possibly reflecting slowing of conduction velocity in the peripheral nerves. In contrast, SII response (response peak at around 80-120 ms) showed a different change in aging. Latencies of the contralateral SII responses showed a trend for shortening in the older adults. There were no significant age-related changes for the amplitudes and ECD strengths. Thus, SI and SII are differently affected by aging. The shortening of the SII latency suggests age-related plastic-adaptive change in SII, which is mediated by the direct thalamocortical pathway.
Complex Medical Engineering (CME), 2012 ICME International Conference on; 01/2012
[Show abstract][Hide abstract] ABSTRACT: We report a 29-year-old man who presented with a 2-year history of progressive stiffness and painful spasms limited to the bilateral lower limbs, exaggerated by auditory and tactile stimuli. His deep tendon reflexes were slightly increased in both lower extremities. His plantar response was flexor. His serum and cerebrospinal fluid were negative for anti-glutamic acid decarboxylase antibodies. Electromyography of antagonist muscle pairs in his distal lower limbs revealed a failure of reciprocal inhibition. We used transcranial magnetic stimulation with a paired-pulse paradigm, delivered to the cortical area of the upper and lower limbs, and revealed significantly enhanced facilitation only in the area of his lower limbs, but not that representing his upper limbs. His symptoms were improved substantially by 20mg/day of oral diazepam. To our knowledge this is the first report of a patient with hyperexcitability limited to the lower limb motor system in a patient with stiff-leg syndrome.
Journal of Clinical Neuroscience 12/2011; 18(12):1720-2. · 1.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report a 68-year-old man who exhibited mild dysarthria and mild right hemiparesis resulted from hypoperfusion of the left hemisphere. An MR angiography showed a severe stenosis at the second portion of left middle cerebral artery (MCA). After the beginning of treatment, the patient suffered from hoarseness, followed by breathing failure. The laryngeal fiber exhibited right vocal cord paresis. Unilateral cortico-bulbar tract dysfunction does not typically cause vocal cord palsy. However, several cases indicate the involvement of a dominant projection from the contralateral cortico-bulbar tract to the vocal cord. In the present case, hypoperfusion of the left hemisphere might have temporarily produced right vocal cord palsy, considering the stenosis of the left MCA.
[Show abstract][Hide abstract] ABSTRACT: Epilepsy is a common disease with a high incidence of about one percent. Knowledge of seizure semiology and correct reading of EEG findings are important for diagnosis of epilepsy. Because the primary therapy for epilepsy is antiepileptic drugs (AEDs), including several ones that are newly permitted in Japan, we need to prescribe them based on an understanding of their actions and interaction mechanisms. However, we also need to consider early surgical treatment for temporal lobe epilepsy with hippocampal sclerosis. In the therapeutic decision for adult epilepsy patients many factors such as employment, marriage, child bearing, and co-existent disease need to be considered. The present review provides an overview of the basis of epilepsy practice for neurologists treating adults with epilepsy, including a discussion of new AEDs, epilepsy surgery, women with epilepsy, and epilepsy in the elderly.
[Show abstract][Hide abstract] ABSTRACT: Charles Bonnet syndrome refers to visual hallucinations in patients with visual acuity loss or visual field loss without dementia. We report a case of Charles Bonnet syndrome following syphilitic optic neuritis. A 62-year-old man was admitted to our hospital suffering acute bilateral visual loss in a few months. On admission, he was almost blind and his optic discs were found to be atrophic on fundoscopy. In addition to increased cell counts and protein concentration in cerebrospinal fluid (CSF), serum and CSF rapid plasma reagin tests were positive. A diagnosis of syphilitic optic neuritis was made and he was treated with intravenous penicillin G (24 million units per day for 14 days) without any recovery. After treatment finished, he began to experience complex, vivid, elaborate and colored visual hallucinations. He recognized these visions as unreal and felt distressed by them. No cognitive impairment was observed on several neuropsychological tests. We diagnosed the patient as suffering from Charles Bonnet syndrome. Brain MRI revealed diffuse mild atrophy of the cerebral cortex and multiple T2 high signal intensity lesions in the deep cerebral white matter. Single photon emission computed tomography revealed decreased regional cerebral blood flow in bilateral medial occipital lobes. Administration of olanzapine resulted in a partial remission of visual hallucinations. Charles Bonnet syndrome following syphilitic optic neuritis is rare. In the present case, visual loss and dysfunction of bilateral medial occipital lobes may have triggered the visual hallucinations, which were alleviated by olanzapine.
[Show abstract][Hide abstract] ABSTRACT: We report a case of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) concomitant with acquired von Willebrand syndrome. A 33-year-old man developed motor and sensory polyneuropathy with electrophysiological conduction slowing. At this time, M-protein was absent He was diagnosed with CIDP and received intravenous immunoglobulin and subsequent oral corticosteroids, which resulted in almost complete remission for over 10 years. At the age of 44, he presented with chronic anemia. Laboratory tests and colonoscopy revealed that he had acquired von Willebrand syndrome with monoclonal gammopathy of undetermined significance (IgG lambda type) and colon cancer. Bleeding symptoms were.resolved with intravenous immunoglobulin, but not with supplementation of factor VIII. Shortly after successful excision of the cancer, CIDP and acquired von Willebrand syndrome simultaneously recurred. Intravenous immunoglobulin produced rapid improvement of both neurological and hematological abnormalities. Concurring CIDP and acquired von Willebrand syndrome in the present case may indicate that the conditions have a partly common immunological background including monoclonal gammopathy and a potential common autoantibody-mediated mechanism. Alternatively, dysfunction of von Willebrand factor may increase blood-nerve barrier permeability, inducing the recurrence of CIDP.