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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.

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

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

Background Although spinal decompression surgery is an effective treatment for myelopathy-induced upper limb pain, some postoperative patients suffer from residual pain in spite of adequate decompression. However, the neural mechanism underlying the poor outcome of pain relief is still unclear. The goal of this study was to explore the brain mechanisms involved in the poor recovery of upper limb pain after the spinal decompression surgery by using functional connectivity (FC) analysis. Methods In this cross-sectional study, 17 patients who underwent cervical spinal decompression surgery were included. Functional MRI (fMRI) during a tactile stimulus for each hand was performed at 1 day before and 7 days after the surgery. In total, 34 fMRI scans (17 left and right upper limbs, respectively) were obtained before and after the surgery, respectively. The patients were divided into poor-recovery and good-recovery groups, and then we searched for the FC that was related to poor-recovery. Results The poor-recovery group (n = 15) showed significantly stronger connectivity between the postcentral gyrus (postCG) and dorsolateral prefrontal cortex (DLPFC) than the good-recovery group (n = 12) preoperatively. When the cutoff value of the preoperative FC between the left postCG and right middle frontal gyrus included in DLPFC was >0.17, the sensitivity and specificity for poor recovery were 73% and 75%, respectively. Conclusions Our study showed that FC between the postCG and DLPFC may be a predictor of pain relief. This result suggested that assessing FC can lead to more informed surgical interventions for cervical spondylotic myelopathy.

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.

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.

A 70-year-old woman had spontaneous resolution of an embolism in her right middle cerebral artery (MCA) (day 1); another embolism occurred in her left MCA (day 3), which was promptly removed. On day 5, F-FDG PET/CT performed for staging mediastinal lymphoma showed marked FDG accumulation in the left MCA territory, whereas a defect was seen in the right insular region. Eventually, bilateral lesions developed irreversible infarction. Anaerobic metabolism and/or inflammation in acute-phase infarction were the supposed mechanism for the increased accumulation of FDG in her left MCA territory.

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.

Background The connection between the ventrolateral frontal and temporoparietal cortices has an important role in language function on the language-dominant side and spatial awareness on the nondominant side. However, the laterality of these pathways remains controversial. We investigated the laterality of this connection using corticocortical-evoked potentials (CCEPs). Methods From April 2014 to March 2016, 27 patients who had undergone frontotemporal craniotomy were enrolled. With the patients under general anesthesia, subdural electrodes were placed on both frontal and temporoparietal areas intraoperatively. Alternating 1-Hz electrical stimuli were delivered to the pars opercularis and pars triangularis with a stimulus intensity of 10 mA. CCEPs were obtained from temporoparietal areas by averaging the electrocorticogram time-locked to the stimulus onset. The amplitudes and latencies of the CCEP N1 components were compared between the dominant and nondominant sides. Results The median amplitudes of the CCEPs were 335.1 μV (range, 60.2–750) and 125.65 μV (range, 55.1–634) on the dominant and nondominant sides, respectively. The CCEP amplitudes were significantly larger on the dominant side than on the nondominant side (P = 0.013). In contrast, the median latency was 27.8 ms (range, 19.3–36.6) on the language-dominant side and 28.9 ms (range, 8.9–38.5) on the nondominant side. The latencies were not significantly different between the 2 sides (P = 0.604). Conclusions The CCEP amplitudes were significantly larger in the dominant hemisphere. These findings can lead to better hypotheses regarding the relationship between language functions and the development of the network connecting the frontal and temporoparietal cortices.

Background To control bleeding during spinal meningioma surgery, early resection of the dural attachment is important. We report a case of a meningioma where identifying the tumor's dural attachment was difficult because the tumor arose from the denticulate ligament. This report histopathologically and surgically describes this rare occurrence. Case Description A 38-year-old man presented with a mass lesion that was found during a follow-up examination for vestibular schwannoma surgery performed 2 years prior. He was neurologically free of symptoms except for right-sided deafness. Magnetic resonance imaging revealed an intradural extramedullary mass at the C1 level. The tumor had homogeneous enhancement after administration of gadolinium; however, no dural tail sign was seen. Schwannoma was diagnosed, and lesion resection was performed. The hard, white tumor was adherent to the denticulate ligament, and no dural attachment was found. The tumor was totally removed after resection of the denticulate ligament. Histopathologic investigation, based on immunoreactivity to epithelial membrane antigen, revealed that the tumor was a meningioma. In addition to normal fibrous tissue, the denticulate ligament was infiltrated by tumor cells. Based on histopathologic findings and the absence of a dural attachment, we suspect that this meningioma originated from the denticulate ligament. Conclusions If it is difficult to find the dural attachment during spinal meningioma surgery, the possibility of a denticulate meningioma should be considered, and the attachment should be resected as soon as possible.

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 recent years, stereotactic electroencephalography(SEEG)has been focused on as a new invasive method for epileptic focus detection. Although the covering area of the brain surface is smaller than the invasive estimation with subdural electrodes, SEEG can evaluate foci that are deeply seated, noncontiguous leaves, and/or bilateral hemispheres. In addition, SEEG can capture consecutive changes in seizure activity in three dimensions. Due to the development of neuroimaging, computer-assisted, and robotic surgery technology, SEEG insertion began to be commonly used worldwide. Although the approximate complication rates of SEEG are estimated as 1% to 3%, which is lower than that of subdural electrode implantation, the risks of major complications, such as permanent neurological deficit and death, are equivalent. Therefore, meticulous procedure must be needed. To introduce SEEG for intractable partial epilepsy, we acquired approval from the institutional review board and concurrently imported surgical devices and electrodes from the manufacturer in the United States for two surgical candidates. We safely performed SEEG insertion, focal identification, and brain functional mapping by cortical electrical stimulation in two cases. Insertion was difficult for some electrodes, which could be due to the lack of adequate surgical device and large skull angle. Hopefully, the official installation of SEEG will be planned in the near future. We hereby reported tips and pitfalls of SEEG implantation through our own experience in a single institute.

Background Depressed mood following neuronal damage not only impedes functional recovery but also negatively affects quality of life for many patients. Depressed patients with cervical myelopathy often show improvement in both mood and motor function after spinal decompression surgery; however, the neural mechanism underlying this psychological benefit from surgery remains unclear. The aim of this study was to clarify the brain sites that relate to alleviation of depression after spinal decompression surgery. Methods We compared brain activity of patients with cervical myelopathy (n = 6) with healthy participants (n = 5) using functional magnetic resonance imaging. We then analyzed functional magnetic resonance imaging data to find the brain regions that correlated with depression severity (n = 12; 6 preoperative patients and 6 postoperative patients) and compared preoperative imaging data with postoperative imaging data from patients. Results Spinal decompression surgery alleviated depression and diminished anterior cingulate cortex activity. Simultaneously, supplementary motor area activity, which was increased in patients with myelopathy compared with control subjects, was diminished after surgery. Conclusions Traditionally, surgical indications for myelopathy are determined by the severity of sensorimotor symptoms without considering psychological symptoms. We anticipate our results will lead to more informed surgical decisions for cervical spondylosis myelopathy.

Introduction Human brain operates with oscillatory activity in different frequency bands. For example, mu rhythm is well known as an idling rhythm observed in the central area related to motor function. We observed some rhythmic pattern in the averaged waveforms in the CCEP investigation (called “oscillatory response” here), which is originally a method to trace connectivity by single electrical pulse stimulation. We report on the frequency and distribution of the oscillatory responses in CCEP. Methods Subjects are 5 intractable epilepsy patients who underwent chronic implantation of subdural electrodes for presurgical evaluation. Written informed consents were obtained from all subjects. Single-pulse stimuli (0.3 ms, 8–10 mA, alternating polarity, 30 × 2 trials) were applied through two adjacent electrodes (52.8 ± 15.3 stimulus sites per patient). CCEP was recorded from subdural electrodes (105.2 ± 31.8 electrodes per patient) placed on the lateral and medial aspect of the cerebral hemisphere. Lateral fronto-parietal area was covered in all subjects. An oscillatory response in CCEP was detected by visual inspection on the averaged waveform according to the following criteria; (1) it has at least two pairs of peak and trough spaced equally, (2) it can be overlapped with other evoked responses (typical N1/ N2 response). If more than one rhythms with different frequencies were observed in the same electrode, we counted the largest one in amplitude. Results Totally, 2362 oscillatory responses (7.9%) were detected in 29891 observations in 5 subjects, including 443 alpha-band responses (7.5–13.5 Hz), 312 beta-band responses (13.5–30 Hz) and 1505 theta-band responses (3.5–7.5 Hz). Theta rhythm was observed predominantly in the temporal lobe including the basal temporal area (the occurrence rate was 12.45%). Alpha rhythm was observed more often in the parietal lobe including the postcentral gyrus (the occurrence rate was 4.57%), while beta rhythm was often observed around precentral gyrus (the occurrence rate was 1.98%). The frequency of the resting rhythmic activity was equal to that of oscillatory CCEP response in the alpha band in the postcentral gyrus in all subjects. This alpha activity was considered as mu rhythm in all the 3 subjects who performed a hand grasping task. Conclusion Single pulse electrical stimulation evoked oscillatory CCEP responses preferentially in the temporal lobe and the perirolandic area. The correspondence of frequency between the oscillatory response and mu rhythm implies the phase resetting of the physiological oscillation by exogenous input. This unique oscillatory CCEP may help to map these functionally important cortical regions.

Background We examine the impact of the installation of integrated hybrid operating rooms (ORs) that allow both surgical and endovascular procedures and are designed for less invasive and 1-stage treatment of complex neurovascular lesions. Methods We retrospectively analyzed our experience in the treatment of complex neurovascular lesions in a hybrid OR. Results Three patients with distal middle cerebral artery (MCA) aneurysms underwent a proximal clip occlusion or endovascular trapping with a superficial temporal artery–MCA bypass after correct localization of the recipient branch distal to the aneurysm using superselective intra-arterial infusion of indocyanine green under an operating microscope. Two patients with innominate artery stenosis were treated with retrograde stenting from the common carotid artery (CCA) with distal protection of the internal carotid artery (ICA) alone, and with antegrade stenting with dual protection of the ipsilateral ICA and the vertebral artery. Two patients with tandem stenosis of the proximal CCA and carotid bifurcation underwent 1-stage retrograde stenting combined with a carotid endarterectomy. A patient with the innominate artery and the proximal CCA stenosis underwent staged percutaneous antegrade angioplasty of the innominate artery followed by retrograde stenting of both lesions. A patient with tandem stenosis of the subclavian and innominate arteries underwent 1-stage retrograde stenting. In 2 patients with carotid stenosis that was difficult to access via the endovascular route, carotid stenting was performed by direct puncture of the proximal CCA. No patients suffered from new postoperative neurologic deficits. Conclusions The integration of a high-end hybrid OR enables combined endovascular and surgical procedures for complex neurovascular and brachiocephalic lesions in a 1-stage treatment.

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 (

Cortico-cortical evoked potential (CCEP) has been widely used to probe brain network. Typically CCEP waveform consists of two negative potentials, N1 (peak: 10–50 ms) and N2 (peak: 100–500 ms). We, however, occasionally encounter atypical responses, such as those with prolonged N1 peak latency. We attempt to classify these atypical patterns and clarify their anatomical distribution. We retrospectively reviewed CCEP responses in two patients with intractable focal epilepsy, in whom CCEPs were obtained bystimulating all the implanted subdural electrodes (IRB#443). We classified CCEP into 6 groups based upon the N1 and N2 peak latencies; IA: N1 (10–50 ms), N2 (100–500 ms), IB: N1 (10–50 ms), N2: (50–100 ms), IIA: N1 (50–100 ms), N2: (100–500 ms), IIB: N1 (50–100 ms) without definite N2, III: mirror CCEP response with positive peaks, IV: N1 (100–500 ms) without definite N2. Atypical CCEP responses (IIA, IIB, III, IV) accounted for 16.0% among all the recording. They mostly distributed in the temporal lobe. There was a tendency of preferred locations for each pattern; IIB in the lateral temporal region and frontal operculum, III in the superior temporal gyrus and mesial temporal region, IV in the temporal pole. Further case accumulation is warranted to verify the results, which helps understand the significance of CCEP for presurgical evaluation.

The superior parietal lobule (SPL) and the medial parietal cortex are associated with integration of various kinds of information. Little is known about connections from the superior and medial parietal cortices in humans. Our objective is to delineate their connectivity by means of cortico-cortical evoked potential (CCEP). Subjects were eight patients who underwent chronic subdural electrode placement covering the dorso-lateral (SPL) or medial parietal cortices. Single-pulse electrical stimuli were delivered and CCEPs were obtained from the frontal and parietal areas by averaging electrocorticograms time-locked to stimuli. SPL stimulation elicited 75 CCEPs at the precuneus, precentral gyrus, the dorsal premotor area (dorsal PM). The precuneus elicited 66 CCEPs in the inferior parietal lobule (IPL), dorsal premotor area (PM) and SPL. The posterior cingulate cortex elicited 36 CCEPs at the middle cingulate cortex, SPL and the precuneus. This study demonstrated reciprocal connections between the superior and medial parietal cortices. While the precuneus tends to connect with the lateral frontal area, posterior cingulate cortex with medial frontal area. These findings would account for functional differentiation between these areas, and may help us understand seizure propagation in patients with parietal lobe epilepsy.

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.