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Objective In order to evaluate the clinical utility even under general anesthesia, the present study aimed to clarify the effect of anesthesia on the cortico–cortical evoked potentials (CCEPs). Methods We analyzed 14 patients’ data in monitoring the integrity of the dorsal language pathway by using CCEPs both under general anesthesia with propofol and remifentanil and awake condition, with the main aim of clarifying the effect of anesthesia on the distribution and waveform of CCEPs. Results The distribution of larger CCEP response sites, including the locus of the maximum CCEP response site, was marginally affected by anesthesia. With regard to similarity of waveforms, the mean waveform correlation coefficient indicated a strong agreement. CCEP N1 amplitude increased by an average of 25.8% from general anesthesia to waking, except three patients. CCEP N1 latencies had no correlation in changes between the two conditions. Conclusions We demonstrated that the distribution of larger CCEP responses was marginally affected by anesthesia and that the CCEP N1 amplitude had tendency to increase from general anesthesia to the awake condition. Significance The CCEP method provides the efficiency of intraoperative monitoring for dorsal language white matter pathway even under general anesthesia.

Noninvasive brain imaging studies have shown that higher visual processing of objects occurs in neural populations that are separable along broad semantic categories, particularly living versus nonliving objects. However, because of their limited temporal resolution, these studies have not been able to determine whether broad semantic categories are also reflected in the dynamics of neural interactions within cortical networks. We investigated the time course of neural propagation among cortical areas activated during object naming in 12 patients implanted with subdural electrode grids prior to epilepsy surgery, with a special focus on the visual recognition phase of the task. Analysis of event-related causality revealed significantly stronger neural propagation among sites within ventral temporal lobe (VTL) at early latencies, around 250 ms, for living objects compared to nonliving objects. Differences in other features, including familiarity, visual complexity, and age of acquisition, did not significantly change the patterns of neural propagation. Our findings suggest that the visual processing of living objects relies on stronger causal interactions among sites within VTL, perhaps reflecting greater integration of visual feature processing. In turn, this may help explain the fragility of naming living objects in neurological diseases affecting VTL.

Acromegaly is characterized by autonomous excessive growth hormone (GH) secretion, generally due to GH-producing pituitary adenoma, and is associated with various systemic comorbidities including diabetes mellitus. Polycystic kidney disease (PKD) is characterized by the growth of numerous cysts in the kidneys that deteriorate renal function. While possible renal effects of excessive GH exposure have been a current issue in experimental medicine, only five cases of coexisting acromegaly and PKD have been reported previously, and little is known regarding the influence of acromegaly on renal disease. We treated a 50-year-old male with diabetes mellitus who showed a sudden and rapid decline of renal function along with increasing proteinuria, which led to diagnoses of PKD and acromegaly. His urinary protein levels were increased together with excessive GH secretion and worsening glycemic control. An increase of total kidney volume was also noted. Transsphenoidal surgery for the pituitary adenoma was successfully performed. Marked improvement of hyperglycemia and proteinuria were observed after the surgery, but renal function was unchanged. The patient's clinical course suggested common aspects of excessive GH secretion as an accelerating factor of the progression of diabetic nephropathy and PKD via direct and indirect pathways. Although coexisting acromegaly and PKD is clinically rare, vigilance for early diagnosis of acromegaly is appropriate in patients with diabetes and/or PKD, especially in those showing unexpected exacerbation of renal dysfunction.

BACKGROUND AND PURPOSE: Collateral vessels in Moyamoya disease represent potential sources of bleeding. To test whether these cortical distributions vary among subtypes, we investigated cortical terminations using both standardized MR imaging and MRA. MATERIALS AND METHODS: Patients with Moyamoya disease who underwent MR imaging with MRA in our institution were enrolled in this study. MRA was spatially normalized to the Montreal Neurological Institute space; then, collateral vessels were measured on MRA and classified into 3 types of anastomosis according to the parent artery: lenticulostriate, thalamic, and choroidal. We also obtained the coordinates of collateral vessel outflow to the cortex. Differences in cortical terminations were compared among the 3 types of anastomosis. RESULTS: We investigated 219 patients with Moyamoya disease, and a total of 190 collateral vessels (lenticulostriate anastomosis, n = 72; thalamic anastomosis, n = 21; choroidal anastomosis, n = 97) in 46 patients met the inclusion criteria. We classified the distribution patterns of collateral anastomosis as follows: lenticulostriate collaterals outflowing anteriorly (P

The areas that directly inhibit motor responses in the human brain remain not fully clarified, although the pre-supplementary motor area and lateral premotor areas have been implicated. The objective of the present study was to delineate the critical areas for response inhibition and the associated functional organization of the executive action control system in the frontal lobe. The subjects were eight intractable focal epilepsy patients with chronic subdural or depth electrode implantation for presurgical evaluation covering the frontal lobe (five for left hemisphere, three for right). We recorded event-related potentials to a Go/No-Go task. We then applied a brief 50 Hz electrical stimulation to investigate the effect of the intervention on the task. Brief stimulation was given to the cortical areas generating discrete event-related potentials specific for the No-Go trials (1–3 stimulation sites/patient, a total of 12 stimulation sites). We compared the locations of event-related potentials with the results of electrical cortical stimulation for clinical mapping. We also compared the behavioural changes induced by another brief stimulation with electrical cortical stimulation mapping. As the results, anatomically, No-Go-specific event-related potentials with relatively high amplitude, named ‘large No-Go event-related potentials’, were observed predominantly in the secondary motor areas, made up of the supplementary motor area proper, the pre-supplementary motor area, and the lateral premotor areas. Functionally, large No-Go event-related potentials in the frontal lobe were located at or around the negative motor areas or language-related areas. Brief stimulation prolonged Go reaction time at most stimulation sites (66.7%) [P

The spatiotemporal dynamics of interaction between slow (delta or infraslow) waves and fast (gamma) activities during wakefulness and sleep are yet to be elucidated in human electrocorticography (ECoG). We evaluated phase-amplitude coupling (PAC), which reflects neuronal coding in information processing, using ECoG in 11 patients with intractable focal epilepsy. PAC was observed between slow waves of 0.5–0.6 Hz and gamma activities, not only during light sleep and slow-wave sleep (SWS) but even during wakefulness and rapid eye movement (REM) sleep. While PAC was high over a large region during SWS, it was stronger in the posterior cortical region around the temporoparietal junction than in the frontal cortical region during REM sleep. PAC tended to be higher in the posterior cortical region than in the frontal cortical region even during wakefulness. Our findings suggest that the posterior cortical region has a functional role in REM sleep and may contribute to the maintenance of the dreaming experience.

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.

The cortical motor areas are activated not only during contralateral limb movements but also during ipsilateral limb movements. Although these ipsilateral activities have been observed in several brain imaging studies, their functional role is poorly understood. Due to its high temporal resolution and low susceptibility to artifacts from body movements, the electrocorticogram (ECoG) is an advantageous measurement method for assessing the human brain function of motor behaviors. Here, we demonstrate that contra- and ipsilateral movements share a similarity in the high-frequency band of human ECoG signals. The ECoG signals were measured from the unilateral sensorimotor cortex while patients conducted self-paced movements of different body parts, contra- or ipsilateral to the measurement side. The movement categories (wrist, shoulder, or ankle) of ipsilateral movements were decoded as accurately as those of contralateral movements from spatial patterns of the high-frequency band of the precentral motor area (the primary motor and premotor areas). The decoder, trained in the high-frequency band of ipsilateral movements generalized to contralateral movements, and vice versa, confirmed that the activity patterns related to ipsilateral limb movements were similar to contralateral ones in the precentral motor area. Our results suggest that the high-frequency band activity patterns of ipsilateral and contralateral movements might be functionally coupled to control limbs, even during unilateral movements.

In order to preserve postoperative language function, we recently proposed a new intraoperative method to monitor the integrity of the dorsal language pathway (arcuate fasciculus; AF) using cortico-cortical evoked potentials (CCEPs). Based on further investigations (20 patients, 21 CCEP investigations), including patients who were not suitable for awake surgery (five CCEP investigations) or those without preoperative neuroimaging data (eight CCEP investigations including four with untraceable tractography due to brain edema), we attempted to clarify the clinical impact of this new intraoperative method. We monitored the integrity of AF by stimulating the anterior perisylvian language area (AL) by recording CCEPs from the posterior perisylvian language area (PL) consecutively during both general anesthesia and awake condition. After tumor resection, single-pulse electrical stimuli were also applied to the floor of the removal cavity to record subcortico-cortical evoked potentials (SCEPs) at AL and PL in 12 patients (12 SCEP investigations). We demonstrated that (1) intraoperative dorsal language network monitoring was feasible even when patients were not suitable for awake surgery or without preoperative neuroimaging studies, (2) CCEP is a dynamic marker of functional connectivity or integrity of AF, and CCEP N1 amplitude could even become larger after reduction of brain edema, (3) a 50% CCEP N1 amplitude decline might be a cut-off value to prevent permanent language dysfunction due to impairment of AF, (4) a correspondence (

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.

In order to preserve postoperative language function, we recently proposed a new intraoperative method to monitor the integrity of the dorsal language pathway (arcuate fasciculus; AF) using cortico–cortical evoked potentials (CCEPs). Based on further investigations (20 patients, 21 CCEP investigations), including patients who were not suitable for awake surgery (five CCEP investigations) or those without preoperative neuroimaging data (eight CCEP investigations including four with untraceable tractography due to brain edema), we attempted to clarify the clinical impact of this new intraoperative method. We monitored the integrity of AF by stimulating the anterior perisylvian language area (AL) by recording CCEPs from the posterior perisylvian language area (PL) consecutively during both general anesthesia and awake condition. After tumor resection, single‐pulse electrical stimuli were also applied to the floor of the removal cavity to record subcortico‐cortical evoked potentials (SCEPs) at AL and PL in 12 patients (12 SCEP investigations). We demonstrated that (1) intraoperative dorsal language network monitoring was feasible even when patients were not suitable for awake surgery or without preoperative neuroimaging studies, (2) CCEP is a dynamic marker of functional connectivity or integrity of AF, and CCEP N1 amplitude could even become larger after reduction of brain edema, (3) a 50% CCEP N1 amplitude decline might be a cut‐off value to prevent permanent language dysfunction due to impairment of AF, (4) a correspondence (

Background and Purpose — Optimizing prehospital stroke care is important because effective treatments for acute stroke require a narrow therapeutic time window. We developed a smartphone-assisted prehospital medical information system (SPMIS) to facilitate research on prehospital stroke care. Methods — Prehospital medical information was input into the SPMIS application installed on smartphones by emergency medical staff, sent to a server through the Internet, and connected with in-hospital information. Using SPMIS, we analyzed data on 914 patients transferred to our institution by ambulance between April 2012 and March 2013. Results — The data analyzed were the sensitivity and specificity of the prehospital diagnosis and prehospital stroke scale and the relationship between prehospital vital signs and forms of stroke. These analyses could be performed semiautomatically in a few hours. Conclusions — SPMIS enabled us to analyze the prehospital information of patients with stroke in a short time with little effort. More large-scale studies on prehospital stroke care will become feasible using SPMIS, which may lead to advances in stroke treatment.