Ictal direct current shifts contribute to defining the core ictal focus in epilepsy surgery

難治てんかん焦点の新しいバイオマーカー「発作時DC電位」 --国内5施設の共同研究での世界初の成果--. 京都大学プレスリリース. 2022-09-05.Identifying the minimal and optimal epileptogenic area to resect and cure is the goal of epilepsy surgery. To achieve this, EEG analysis is recognized as the most direct way to detect epileptogenic lesions from spatiotemporal perspectives. Although ictal direct-current shifts (icDCs; below 1 Hz) and ictal high-frequency oscillations (icHFOs; above 80 Hz) have received increasing attention as good indicators that can add more specific information to the conventionally defined seizure-onset zone, large cohort studies on postoperative outcomes are still lacking. This work aimed to clarify whether this additional information, particularly icDCs which is assumed to reflect extracellular potassium concentration, really improve postoperative outcomes. To assess the usefulness in epilepsy surgery, we collected unique EEG datasets recorded with a longer time constant of 10 sec using an alternate current amplifier. 61 patients [15 with mesial temporal lobe epilepsy and 46 with neocortical epilepsy] who had undergone invasive presurgical evaluation for medically refractory seizures at five institutes in Japan, were retrospectively enrolled in this study. Among intracranially implanted electrodes, the two core electrodes of both icDCs and icHFOs were independently identified by board-certified clinicians based on unified methods. The occurrence patterns, such as their onset time, duration, and amplitude (power) were evaluated to extract the features of both icDCs and icHFOs. Additionally, we examined whether the resection ratio of the core electrodes of icDCs and icHFOs independently correlated with favorable outcomes. A total of 53 patients with 327 seizures were analyzed for wide-band EEG analysis, and 49 patients were analyzed for outcome analysis. icDCs were detected in the seizure-onset zone more frequently than icHFOs among both patients (92% vs. 71%) and seizures (86% vs. 62%). Additionally, icDCs significantly preceded icHFOs in patients exhibiting both biomarkers, and icDCs occurred more frequently in neocortical epilepsy patients than in mesial temporal lobe epilepsy patients. Finally, although a low corresponding rate was observed for icDCs and icHFOs (39%) at the electrode level, complete resection of the core area of icDCs significantly correlated with favorable outcomes, similar to icHFO outcomes. Our results provide a proof of concept that the independent significance of icDCs from icHFOs should be considered as reliable biomarkers to achieve favorable outcomes in epilepsy surgery. Moreover, the different distribution of the core areas of icDCs and icHFOs may provide new insights into the underlying mechanisms of epilepsy, in which not only neurons but also glial cells may be actively involved via extracellular potassium levels

ヒトの到達運動における後部頭頂葉の役割 : 視覚性運動失調に対する臨床的意義

京都大学0048新制・論文博士博士(医学)乙第12817号論医博第2079号新制||医||1004(附属図書館)31304京都大学大学院医学研究科脳統御医科学系専攻(主査)教授 河野 憲二, 教授 金子 武嗣, 教授 大森 治紀学位規則第4条第2項該当Doctor of Medical ScienceKyoto UniversityDFA

Alpha-band desynchronization in human parietal area during reach planning.

[Objective]The symptoms with optic ataxia suggest that simple and visually guided hand movements are controlled by 2 different neural substrates. To assess the differential frequency-coded posterior parietal cortex (PPC) role in planning visuo-motor goal-directed tasks, we studied the action specificity of event-related desynchronization (ERD) in this area. [Methods]We investigated cortical activity by electroencephalography, while 16 healthy subjects performed self-paced reaching or wrist extension (control) movements. Time–frequency representations were calculated for each movement during the preparatory period. [ResultsERD dynamics in upper alpha-band indicated that preparing a goal-directed action activates contralateral PPC to the moving hand around 1.2 s before starting the movement, while this activation is later (around 0.7 s) in preparing a not-goal-directed action. The posterior dominant rhythm had peak frequency of lower alpha-band at bilateral parietal. [Conclusions]Posterior parietal cortex encodes goal-directed movement preparation through upper alpha-band activity, whereas general attention is processed via lower alpha-band oscillations. [Significance]Preparing to reach an object engages posterior parietal cortex earlier than a not-goal directed movement

Network hyperexcitability in a patient with partial reading epilepsy: converging evidence from magnetoencephalography, diffusion tractography, and functional magnetic resonance imaging.

[Objective]The pathophysiological mechanisms of partial reading epilepsy are still unclear. We delineated the spatial–temporal characteristics of reading-induced epileptic spikes and hemodynamic activation in a patient with partial reading epilepsy. [Methods]Magnetoencephalography (MEG) was recorded during silent letter-by-letter reading, and the source of reading-induced spikes was estimated using equivalent current dipole (ECD) analysis. Diffusion tractography was employed to determine if the white matter pathway connected spike initiation and termination sites. Functional magnetic resonance imaging (fMRI) was employed to determine the spatial pattern of hemodynamic activation elicited by reading. [Results]In 91 spike events, ECDs were clustered in the left posterior basal temporal area (pBTA) during Katakana reading. In 8 of these 91 events, when the patient continued to read >30 min, another ECD cluster appeared in the left ventral precentral gyrus/frontal operculum with a time-difference of ∼24 ms. Probabilistic diffusion tractography revealed that the long segment of the arcuate fasciculus connected these two regions. fMRI conjunction analysis indicated that both Katakana and Kanji reading activated the left pBTA, but Katakana activated the left lateral frontal areas more extensively than Kanji. [Conclusions]Prolonged reading of Katakana induced hyper-activation of the cortical network involved in normal language function, concurrently serving as the seizure onset and symptomatogenic zones. [Significance]Reflex epilepsy is believed to result from intrinsic hyper-excitability in the cortical regions recruited during behavioral states that trigger seizures. Our case shows that reading epilepsy can arise from a hyperexcitable network of cortical regions. Physiological activation of this network can have cumulative effects, resulting in greater reciprocal network propagation and electroclinical seizures. These effects, in turn, may give insights into the brain networks recruited by reading

Bereitschaftspotential augmentation by neuro-feedback training in Parkinson's disease

[Objective]Decreased early Bereitschaftspotential (BP) is one of the electrophysiological characteristics in patients with Parkinson's disease (PD). We examined whether PD patients could increase BP amplitude by means of neuro-feedback (NFB) training for their slow cortical potentials (SCPs). [Methods]We worked with 10 PD patients and 11 age-matched controls. BP was measured for self-paced button pressing by their right thumb. The subjects were instructed to make the introspective efforts to produce negative SCPs (negativation). The one-day session consisted of three trials, that is, the first BP, NFB training and the second BP, and each patient performed this routine for 2–4 days. Amplitudes of the first and second BPs were compared between the two groups that were divided depending on NFB performance. [Results]Good NFB performance had the tendency of larger early BP in the second BP recording than in the first one, whereas in the poor NFB performance the early BP was smaller in the second BP recording than in the first one in both patient and normal groups (p < 0.001). [Conclusions] Good NFB performance of negativation could increase excitatory field potentials of pyramidal cells for the generation of early BP. [Significance]Voluntary regulation of SCPs could enhance BP in PD patients and in aged controls

Absence of an Autonomic Sign Assists in the Diagnosis of Extratemporal Lobe Epilepsy Manifesting Generalized Convulsion with Retained Awareness

We herein report two epilepsy patients with the seizure focus in the non-dominant hemisphere manifesting secondarily generalized convulsion (sGC) with retained awareness characterized by a lack of autonomic signs although GC was complicated by respiratory arrest. Given the semiology and electrophysiological findings, the seizure activity was considered to propagate to the supplementary-motor area and the bilateral primary-motor area, with a clinical manifestation of sGC. The absence of autonomic signs during GC can be a key indicator that the seizure remains in the bilateral suprasylvian area and thus does not involve the region necessary for awareness preservation, which may assist in the diagnosis of this atypical epileptic seizure

Associations of obstructive sleep apnea with truncal skeletal muscle mass and density

Sarcopenia has been associated with several conditions relevant to obstructive sleep apnea (OSA), such as aging and obesity, but a direct relationship between OSA and skeletal muscle alterations has not been identified. This study investigated associations between computed tomography (CT)-measured skeletal muscle indices and OSA severity. Analyzed were 334 patients who underwent polysomnography to diagnose OSA. Lumbar skeletal muscles were assessed with CT for the skeletal muscle mass index (SMI, cross-sectional area, normalized for height squared) and skeletal muscle density (SMD, fat infiltration). The apnea-hypopnea index (AHI) correlated positively with the SMI and negatively with SMD in both men and women. The AHI was weakly associated with SMI only in men (β = 0.11, P = 0.017) after adjustment for the body mass index (BMI) (BMI: β = 0.61, P < 0.001 in men, β = 0.65, P < 0.001 in women). The association of AHI and SMD was not significant after adjustment for BMI (BMI: β = −0.42, P < 0.001 in men, β = −0.64, P < 0.001 in women). Severity of OSA correlated with increases in skeletal muscle mass rather than muscle depletion and skeletal muscle adiposity. These associations were limited compared with the stronger associations between obesity and skeletal muscles

Adrenal gland size in obstructive sleep apnea: Morphological assessment of hypothalamic pituitary adrenal axis activity.

ObjectivesThe association of obstructive sleep apnea (OSA) with hypothalamic pituitary adrenal (HPA) axis activation has not been fully understood from results of previous studies using hormonal assessments. We aimed to investigate the relationship between adrenal size, a potential marker reflecting HPA axis activity, and sleep parameters related to OSA.MethodsWe retrospectively reviewed data on 284 consecutive adult patients aged 20 to 80 y who had undergone polysomnography and abdominal computed tomography (CT). OSA was defined as none/mild (apnea-hypopnea index [AHI] ResultsAdrenal size was greater in participants with severe OSA than in those with none/mild or moderate OSA (adrenal body width: 6.03 mm, none/mild OSA; 6.09 mm, moderate OSA; 6.78 mm, severe OSA; p ConclusionsResults indicated that adrenal glands may enlarge in response to longstanding sleep fragmentation, suggesting the involvement of OSA in HPA axis augmentation

Left anterior temporal cortex actively engages in speech perception: A direct cortical stimulation study.

Recent neuroimaging studies proposed the importance of the anterior auditory pathway for speech comprehension. Its clinical significance is implicated by semantic dementia or pure word deafness. Neurodegenerative or cerebrovascular nature, however, precluded precise localization of the cortex responsible for speech perception. Electrical cortical stimulation could delineate such localization by producing transient, functional impairment. We investigated engagement of the left anterior temporal cortex in speech perception by means of direct electrical cortical stimulation. Subjects were two partial epilepsy patients, who underwent direct cortical stimulation as a part of invasive presurgical evaluations. Stimulus sites were coregistered to presurgical 3D-MRI, and then to MNI standard space for anatomical localization. Separate from the posterior temporal language area, electrical cortical stimulation revealed a well-restricted language area in the anterior part of the superior temporal sulcus and gyrus (aSTS/STG) in both patients. Auditory sentence comprehension was impaired upon electrical stimulation of aSTS/STG. In one patient, additional investigation revealed that the functional impairment was restricted to auditory sentence comprehension with preserved visual sentence comprehension and perception of music and environmental sounds. Both patients reported that they could hear the voice but not understand the sentence well (e.g., heard as a series of meaningless utterance). The standard coordinates of this restricted area at left aSTS/STG well corresponded with the coordinates of speech perception reported in neuroimaging activation studies in healthy subjects. The present combined anatomo-functional case study, for the first time, demonstrated that aSTS/STG in the language dominant hemisphere actively engages in speech perception