Intracranial volumetric evaluation in postnatally repaired myelomeningocele infants.

INTRODUCTION: Most myelomeningocele (MMC) cases present with ventriculomegaly or hydrocephalus, yet a comprehensive volumetric assessment of MMC intracranial structures is lacking. This study aimed to provide baseline data on intracranial structural volumes immediately after birth in MMC infants who underwent repair surgeries after birth (postnatal repair). METHODS: In this retrospective single-center study, we analyzed 52 MMC infants undergoing postnatal repair, utilizing head computed tomography scans at birth for volumetric assessment. Intracranial volume (ICV), lateral ventricles volume (LVV), choroid plexus volume (CPV), and posterior cranial fossa volume (PCFV) were measured. Hydrocephalus was classified into no hydrocephalus, progressive hydrocephalus, and hydrocephalus at birth. Comparative analysis employed the Wilcoxon rank-sum test. Receiver operating characteristic (ROC) analysis discriminated cases with and without ventriculoperitoneal shunt (VPS). RESULTS: The median values were 407.50 mL for ICV, 33.18 mL for LVV, 0.67 mL for CPV, and 21.35 mL for PCFV. Thirty-seven cases (71.15%) underwent VPS. ROC analysis revealed an LVV cut-off value of 6.74 mL for discriminating cases with and without VPS. Progressive hydrocephalus showed no significant difference in ICV but significantly larger LVV compared to no hydrocephalus. Hydrocephalus at birth demonstrated statistically larger ICV and LVV compared to the other two types. CONCLUSION: Baseline volumetric data were provided, and volumetric analysis exhibited statistical differences among three hydrocephalus types. These findings enhance our understanding of intracranial volumetric changes in MMC, facilitating more objective assessments of MMC cases.

Growth patterns and ratios of posterior cranial fossa structures in the Japanese pediatric population: a study utilizing CT scans.

PURPOSE: The changes in the proportion of posterior cranial fossa structures during pediatric development remain unclear. This retrospective study aimed to investigate the growth patterns and ratios of these structures using CT scans. METHODS: Head CT scans of pediatric patients with minor head trauma from Osaka Women's and Children's Hospital between March 2006 and May 2023 were analyzed. The study segmented the intracranial volume (ICV), posterior cranial fossa volume (PCFV), cerebellum volume (CBMV), and brainstem volume (BSV). Correlation coefficients were calculated among the parameters. Patients aged 0 to 10 years were divided into 15 age-related clusters, and mean and standard deviation values were measured. Growth curves were created by plotting mean values sequentially. Ratios such as PCFV/ICV and (CBMV + BSV)/PCFV were examined. Statistical analyses, including unpaired t tests and logarithmic curve fitting, were performed. RESULTS: A total of 234 CT scans (97 from females, 115 from infants under 1 year of age) were analyzed. Positive correlations were observed among the parameters, with the strongest between PCFV and CBMV. The growth curves for ICV, PCFV, CBMV, and BSV exhibited a two-phase process, with rapid growth until approximately 4 years of age, followed by stabilization. The ratios PCFV/ICV and (CBMV + BSV)/PCFV showed increasing trends from birth onwards, stabilizing by 4 and 1 years of age, respectively. CONCLUSION: This study provides insights into the growth patterns and ratios of posterior cranial fossa structures in the pediatric population. The findings demonstrate a two-phase growth process and increasing trends in the examined ratios.

Normal growth curve of choroid plexus in children: implications for assessing hydrocephalus due to choroid plexus hyperplasia.

OBJECTIVE: Pediatric hydrocephalus requires evaluation while accounting for growth of the intracranial structures, but information on choroid plexus growth in children is lacking. This study aimed to create normal growth curves for intracranial volume, choroid plexus volume, and lateral ventricles volume. Additionally, the authors aimed to objectively assess the degree of hydrocephalus caused by choroid plexus hyperplasia (CPH) and to examine the impact of surgical procedures. METHODS: This retrospective study analyzed the head CT scans of pediatric patients with minor head trauma treated at Osaka Women's and Children's Hospital between March 2006 and May 2023. The study segmented and calculated intracranial, choroid plexus, and lateral ventricles volumes. The study also calculated the correlation coefficients among these 3 parameters. Patients aged 0 to 10 years were divided into 15 age-related clusters, and mean ± SD values were calculated for each cluster. Growth curves were created by plotting mean values sequentially. Volume obtained from patients with CPH were z-normalized using mean and SD values and compared. RESULTS: A total of 229 CT scans (94 from females) were analyzed, and positive correlations were observed among intracranial volume, choroid plexus volume, and lateral ventricles volume, with the strongest correlation between the choroid plexus and lateral ventricles volumes. The growth rate of intracranial volume was rapid until approximately 20 months of age, while those of choroid plexus volume and lateral ventricles volume increased rapidly until approximately 1 year of age. Subsequently, choroid plexus volume and lateral ventricles volume plateaued at 1.5 ml and 10 ml, respectively. Three patients with CPH were enrolled and quantitatively evaluated on the basis of the z-normalized volume. Notable abnormal volumes of the choroid plexus (range z-normalized values 24.11-51.17) and lateral ventricles (46.78-122.36) were observed. In 2 patients, improvements in the z-normalized values of intracranial volume and lateral ventricles volume were observed after surgical interventions. Additionally, in 1 patient, choroid plexus volume was reduced by approximately 24% (range z-normalized values 51.17-38.93) after bilateral endoscopic plexus coagulation. CONCLUSIONS: This study provides normal growth curves for intracranial volume, choroid plexus volume, and lateral ventricles volume. Knowledge of these normal values holds the potential for objective assessment of abnormal values associated with hydrocephalus and choroid plexus diseases such as CPH.

Burr hole locations are associated with recurrence in single burr hole drainage surgery for chronic subdural hematoma.

Background: Various factors have been reported as risk factors for chronic subdural hematomas (CSDH) recurrence. However, few studies have quantitatively evaluated the impact of CSDH locations and burr hole positions on recurrence. This study aimed to reveal the relation between CSDH recurrence and the locations of CSDH and burr holes. Methods: Initial single burr hole surgeries for CSDH with a drainage tube between April 2005 and October 2021 at Otemae Hospital were enrolled. Patients' medical records, CSDH volume, and CSDH computed tomography values (CTV) were evaluated. The locations of CSDH and burr holes were assessed using Montreal Neurological Institute coordinates. Results: A total of 223 patients were enrolled, including 34 patients with bilateral CSDH, resulting in 257 surgeries investigated. The rate of CSDH recurrence requiring reoperation (RrR) was 13.5%. The RrR rate was significantly higher in patients aged ≥76 years, those with bilateral CSDH, and those with postoperative hemiplegia. In RrR, the preoperative CSDH volume was significantly larger, and CTV was significantly smaller. The locations of CSDH had no influence on recurrence. However, in RrR, the locations of burr holes were found to be more lateral and more ventral. Multivariate Cox proportional hazards regression analysis showed that bilateral CSDH, more ventral burr hole positions, and postoperative hemiplegia were risk factors for recurrence. Conclusions: The locations of burr holes are associated with CSDH recurrence. In RrR, CSDH profiles tend to show a larger volume and reduced CTV. Hemiplegia after burr hole surgery serves as a warning sign for RrR.

Brain abscess in a patient with generalized dystonia after deep brain stimulation: illustrative case.

BACKGROUND: Infections related to deep brain stimulation (DBS) devices are not rare, but abscess formation in brain parenchyma is extremely rare. OBSERVATIONS: A 50-year-old man with generalized dystonia had undergone DBS of bilateral globus pallidus internus. The authors attempted to remove the bilateral DBS system due to repeated device infections caused by metal allergies. However, the intracranial lead had to be left in place, because the lead was strongly adherent to brain parenchyma. Five years later, magnetic resonance imaging showed ring-like enhancement localized around the tip of the intracranial lead, suggesting brain abscess. In response to the symptoms, the remaining left intracranial electrode was removed. Brain abscesses require several months of treatment with appropriate antibiotics, but good outcomes can be achieved with appropriate treatment. LESSONS: Brain abscess is a rare complication of DBS. In the present case, the infection spread from the subcutaneous infected foci to the intracranial area through the lead, resulting in the formation of a brain abscess. Removing as much of the device as possible from the body is therefore important, even if adhesions with brain parenchyma or other tissues are present, because of the risk of serious complications, as seen in this case.

Cross-wired metal stents for endoscopic bilateral stent-in-stent deployment in malignant hilar biliary obstruction: A multicenter, single-arm, prospective study.

Objectives: The endoscopic bilateral stent-in-stent (SIS) deployment is a challenging procedure. Such difficulty is mainly caused by sticking of the tip of the delivery sheath into the self-expandable metal stents (SEMSs) mesh, requiring an additional dilating procedure. Herein, we assessed the clinical results of using cross-wired metal stent for endoscopic bilateral SIS deployment (BONASTENT M-Hilar) in patients with malignant hilar biliary obstruction (MHBO) in both high-volume and non-high-volume centers. Methods: We prospectively enrolled consecutive patients with MHBO between February 2016 and December 2018 at eight centers. Results: Forty-six patients were enrolled during the study period. The proportions of technical success were 93.5% (43/46) and clinical success (CS) on intention-to-treat and per-protocol analyses were 91.3% (42/46) and 93.0% (40/43), respectively. The proportion of an additional dilating procedure during the primary procedure was 50.0% (23/46). Recurrent biliary obstruction (RBO) on intention-to-treat analysis occurred in 32.6% (15/46) of cases. Almost all of the events were caused by stent ingrowth (14/15). The median survival time and time to RBO were 255 and 349 days, respectively. The probability of stent patency at 3, 6, and 12 months was 86.5%, 63.9%, and 47.6%, respectively. Conclusions: The cross-wired metal stent had excellent technical and CS, although non-high-volume centers were included in this study (UMIN000021441).

Frequency band coupling with high-frequency activities in tonic-clonic seizures shifts from θ to δ band.

OBJECTIVE: To clarify variations in the relationship between high-frequency activities (HFAs) and low-frequency bands from the tonic to the clonic phase in focal to bilateral tonic-clonic seizures (FBTCS), using phase-amplitude coupling. METHODS: This retrospective study enrolled six patients with drug-resistant focal epilepsy who underwent intracranial electrode placement at Osaka University Hospital (July 2018-July 2019). We recorded 11 FBTCS. The synchronization index (SI) and receiver-operating characteristic (ROC) analysis were used to analyze the coupling between HFA amplitude (80-250 Hz) and lower frequencies phase. RESULTS: In the tonic phase, the θ (4-8 Hz)-HFA coupling peaked, and the HFA power occurred at baseline (0 µV) of θ oscillations. In contrast, in the clonic phase, the δ (2-4 Hz)-HFA coupling peaked, and the HFA power occurred at the trough of δ oscillations. ROC analysis indicated that the δ-HFA SI discriminated well the clonic from the tonic phase. CONCLUSIONS: The main low-frequency band modulating the HFA shifted from the θ band in the tonic phase to the δ band in the clonic phase. SIGNIFICANCE: Neurophysiological key frequency bands were implied to be the θ band and δ band in tonic and clonic seizures, respectively, which improves our understanding of FBTCS.

Masked diabetes insipidus in pituitary metastasis from breast cancer after thalamic biopsy: a case report.

BACKGROUND: Symptomatic pituitary metastasis is rare; furthermore, it can result in diabetes insipidus and panhypopituitarism. Since diabetes insipidus is masked by concurrent panhypopituitarism, it can impede the diagnosis of pituitary dysfunction. CASE PRESENTATION: A 68-year-old Japanese female suffering from pituitary and thalamic metastases caused by untreated breast cancer, underwent a biopsy targeting the thalamus, not the pituitary. She lacked prebiopsy pituitary dysfunction symptoms; however, these symptoms unexpectedly occurred after biopsy. Diabetes insipidus was masked by corticosteroid insufficiency, and she showed normal urinary output and plasma sodium levels. Upon commencement of glucocorticoid replacement therapy, the symptoms of diabetes insipidus appeared. CONCLUSIONS: In this case, thalamic biopsy, as opposed to pituitary biopsy, was performed to preserve pituitary function. However, pituitary dysfunction could not be avoided. Caution is necessary for asymptomatic patients with pituitary metastases as invasive interventions, such as surgery, may induce pituitary dysfunction. Moreover, with respect to masked diabetes insipidus, there is a need to carefully consider pituitary dysfunction to avoid misdiagnosis and delayed treatment.

Functional cortical localization of tongue movements using corticokinematic coherence with a deep learning-assisted motion capture system.

Corticokinematic coherence (CKC) between magnetoencephalographic and movement signals using an accelerometer is useful for the functional localization of the primary sensorimotor cortex (SM1). However, it is difficult to determine the tongue CKC because an accelerometer yields excessive magnetic artifacts. Here, we introduce a novel approach for measuring the tongue CKC using a deep learning-assisted motion capture system with videography, and compare it with an accelerometer in a control task measuring finger movement. Twelve healthy volunteers performed rhythmical side-to-side tongue movements in the whole-head magnetoencephalographic system, which were simultaneously recorded using a video camera and examined using a deep learning-assisted motion capture system. In the control task, right finger CKC measurements were simultaneously evaluated via motion capture and an accelerometer. The right finger CKC with motion capture was significant at the movement frequency peaks or its harmonics over the contralateral hemisphere; the motion-captured CKC was 84.9% similar to that with the accelerometer. The tongue CKC was significant at the movement frequency peaks or its harmonics over both hemispheres. The CKC sources of the tongue were considerably lateral and inferior to those of the finger. Thus, the CKC with deep learning-assisted motion capture can evaluate the functional localization of the tongue SM1.

Phase-amplitude coupling between infraslow and high-frequency activities well discriminates between the preictal and interictal states.

Infraslow activity (ISA) and high-frequency activity (HFA) are key biomarkers for studying epileptic seizures. We aimed to elucidate the relationship between ISA and HFA around seizure onset. We enrolled seven patients with drug-resistant focal epilepsy who underwent intracranial electrode placement. We comparatively analyzed the ISA, HFA, and ISA-HFA phase-amplitude coupling (PAC) in the seizure onset zone (SOZ) or non-SOZ (nSOZ) in the interictal, preictal, and ictal states. We recorded 15 seizures. HFA and ISA were larger in the ictal states than in the interictal or preictal state. During seizures, the HFA and ISA of the SOZ were larger and occurred earlier than those of nSOZ. In the preictal state, the ISA-HFA PAC of the SOZ was larger than that of the interictal state, and it began increasing at approximately 87 s before the seizure onset. The receiver-operating characteristic curve revealed that the ISA-HFA PAC of the SOZ showed the highest discrimination performance in the preictal and interictal states, with an area under the curve of 0.926. This study demonstrated the novel insight that ISA-HFA PAC increases before the onset of seizures. Our findings indicate that ISA-HFA PAC could be a useful biomarker for discriminating between the preictal and interictal states.

Motor and sensory cortical processing of neural oscillatory activities revealed by human swallowing using intracranial electrodes.

Swallowing is attributed to the orchestration of motor output and sensory input. We hypothesized that swallowing can illustrate differences between motor and sensory neural processing. Eight epileptic participants fitted with intracranial electrodes over the orofacial cortex were asked to swallow a water bolus. Mouth opening and swallowing were treated as motor tasks, whereas water injection was treated as a sensory task. Phase-amplitude coupling between lower-frequency and high γ (HG) bands (75-150 Hz) was investigated. An α (10-16 Hz)-HG coupling appeared before motor-related HG power increases (burst), and a θ (5-9 Hz)-HG coupling appeared during sensory-related HG bursts. The peaks of motor-related coupling were 0.6-0.7 s earlier than that of HG power. The motor-related HG was modulated at the trough of the α oscillation, and the sensory-related HG amplitude was modulated at the peak of the θ oscillation. These contrasting results can help to elucidate the brain's sensory motor functions.

Swallowing-related neural oscillation: an intracranial EEG study.

OBJECTIVE: Swallowing is a unique movement due to the indispensable orchestration of voluntary and involuntary movements. The transition from voluntary to involuntary swallowing is executed within milliseconds. We hypothesized that the underlying neural mechanism of swallowing would be revealed by high-frequency cortical activities. METHODS: Eight epileptic participants fitted with intracranial electrodes over the orofacial cortex were asked to swallow a water bolus and cortical oscillatory changes, including the high γ band (75-150 Hz) and ß band (13-30 Hz), were investigated at the time of mouth opening, water injection, and swallowing. RESULTS: Increases in high γ power associated with mouth opening were observed in the ventrolateral prefrontal cortex (VLPFC) with water injection in the lateral central sulcus and with swallowing in the region along the Sylvian fissure. Mouth opening induced a decrease in ß power, which continued until the completion of swallowing. The high γ burst of activity was focal and specific to swallowing; however, the ß activities were extensive and not specific to swallowing. In the interim between voluntary and involuntary swallowing, swallowing-related high γ power achieved its peak, and subsequently, the power decreased. INTERPRETATION: We demonstrated three distinct activities related to mouth opening, water injection, and swallowing induced at different timings using high γ activities. The peak of high γ power related to swallowing suggests that during voluntary swallowing phases, the cortex is the main driving force for swallowing as opposed to the brain stem.

Phase-amplitude coupling of ripple activities during seizure evolution with theta phase.

OBJECTIVE: High-frequency activities (HFAs) and phase-amplitude coupling (PAC) are key neurophysiological biomarkers for studying human epilepsy. We aimed to clarify and visualize how HFAs are modulated by the phase of low-frequency bands during seizures. METHODS: We used intracranial electrodes to record seizures of focal epilepsy (12 focal-to-bilateral tonic-clonic seizures and three focal-aware seizures in seven patients). The synchronization index, representing PAC, was used to analyze the coupling between the amplitude of ripples (80-250 Hz) and the phase of lower frequencies. We created a video in which the intracranial electrode contacts were scaled linearly to the power changes of ripple. RESULTS: The main low frequency band modulating ictal-ripple activities was the θ band (4-8 Hz), and after completion of ictal-ripple burst, δ (1-4 Hz)-ripple PAC occurred. The ripple power increased simultaneously with rhythmic fluctuations from the seizure onset zone, and spread to other regions. CONCLUSIONS: Ripple activities during seizure evolution were modulated by the θ phase. The PAC phenomenon was visualized as rhythmic fluctuations. SIGNIFICANCE: Ripple power associated with seizure evolution increased and spread with fluctuations. The θ oscillations related to the fluctuations might represent the common neurophysiological processing involved in seizure generation.

A Swallowing Decoder Based on Deep Transfer Learning: AlexNet Classification of the Intracranial Electrocorticogram.

To realize a brain-machine interface to assist swallowing, neural signal decoding is indispensable. Eight participants with temporal-lobe intracranial electrode implants for epilepsy were asked to swallow during electrocorticogram (ECoG) recording. Raw ECoG signals or certain frequency bands of the ECoG power were converted into images whose vertical axis was electrode number and whose horizontal axis was time in milliseconds, which were used as training data. These data were classified with four labels (Rest, Mouth open, Water injection, and Swallowing). Deep transfer learning was carried out using AlexNet, and power in the high-[Formula: see text] band (75-150[Formula: see text]Hz) was the training set. Accuracy reached 74.01%, sensitivity reached 82.51%, and specificity reached 95.38%. However, using the raw ECoG signals, the accuracy obtained was 76.95%, comparable to that of the high-[Formula: see text] power. We demonstrated that a version of AlexNet pre-trained with visually meaningful images can be used for transfer learning of visually meaningless images made up of ECoG signals. Moreover, we could achieve high decoding accuracy using the raw ECoG signals, allowing us to dispense with the conventional extraction of high-[Formula: see text] power. Thus, the images derived from the raw ECoG signals were equivalent to those derived from the high-[Formula: see text] band for transfer deep learning.

Coupling between infraslow activities and high-frequency oscillations precedes seizure onset.

Infraslow activities and high-frequency oscillations (HFOs) are observed in seizure-onset zones. However, the relation between them remains unclear. In this study, we investigated phase-amplitude coupling between infraslow phase (0.016-1 Hz) and HFOs' amplitude of focal impaired awareness seizures followed by focal to bilateral tonic-clonic seizures, in a 28-year-old right-handed man with a dysembryoplastic neuroepithelial tumor. We recorded five habitual seizures. After the time of seizure onset, a significant increase in the power of HFOs was observed, and the power was significantly coupled with θ (4-8 Hz) phase. In contrast, coupling of infraslow activities and HFOs surged a few minutes before the seizure-onset time, and ictal HFOs discharged after that. Collectively, our results show that coupling of infraslow activities and HFOs precedes the seizure-onset time. We infer that such coupling may be a potential biomarker for seizure prediction.

Utility and Safety of a Novel Fully Covered Metal Stent in Unresectable Distal Malignant Biliary Obstruction.

BACKGROUND: Self-expandable metal stents (SEMSs) are widely used in patients with distal malignant biliary obstruction. A SEMS that can avoid occlusion as much as possible is desirable. AIMS: The aim of this multicenter single-arm prospective study was to assess the clinical effectiveness and safety of a novel fully covered braided SEMS. METHODS: We enrolled consecutive patients with distal malignant biliary obstruction between February 2016 and November 2017 at ten tertiary-care medical centers. RESULTS: We included 79 patients with a median age of 76 years; 47 (59.5%) patients were men. The technical and clinical success rate was 98.7% and 93.6%, respectively. Recurrent biliary obstruction occurred in 14 patients (17.9%); stent ingrowth, overgrowth, migration, and other occurred in five (6.4%), four (5.1%), four (5.1%), and one (1.3%) patients, respectively. All reinterventions in patients with recurrent biliary obstruction were successful via the transpapillary approach. Adverse events occurred in 15 patients (19.2%); cholangitis, pancreatitis, and others occurred in ten (12.8%), three (3.8%), and two (2.6%) patients, respectively. The stent patency probability at 6 months was 48.5%. Median time to stent patency was 171 days, median time to recurrent biliary obstruction was 536 days, and median survival time was 195 days. CONCLUSIONS: We confirmed the utility and safety of a novel fully covered braided SEMS with low axial force and high radial force in patients with malignance biliary obstruction. This novel SEMS is recommended in patients with distal malignant biliary obstruction.

Comparison of the efficacy and safety of endoscopic ultrasound-guided choledochoduodenostomy and hepaticogastrostomy for malignant distal biliary obstruction: Multicenter, randomized, clinical trial.

BACKGROUND AND AIM: Endoscopic ultrasound-guided biliary drainage (EUS-BD) can be carried out by two different approaches: choledochoduodenostomy (CDS) and hepaticogastrostomy (HGS). We compared the efficacy and safety of these approaches in malignant distal biliary obstruction (MDBO) patients using a prospective, randomized clinical trial. METHODS: Patients with malignant distal biliary obstruction after failed endoscopic retrograde cholangiopancreatography were randomly selected for either CDS or HGS. The procedures were carried out at nine tertiary centers from September 2013 to March 2016. Primary endpoint was technical success rate, and the noninferiority of HGS to CDS was examined with a one-sided significance level of 5%, where the noninferiority margin was set at 15%. Secondary endpoints were clinical success, adverse events (AE), stent patency, survival time, and overall technical success including alternative EUS-BD procedures. RESULTS: Forty-seven patients (HGS, 24; CDS, 23) were enrolled. Technical success rates were 87.5% and 82.6% in the HGS and CDS groups, respectively, where the lower limit of the 90% confidence interval of the risk difference was -12.2% (P = 0.0278). Clinical success rates were 100% and 94.7% in the HGS and CDS groups, respectively (P = 0.475). Overall AE rate, stent patency, and survival time did not differ between the groups. Overall technical success rates were 100% and 95.7% in the HGS and CDS groups, respectively (P = 0.983). CONCLUSIONS: This study suggests that HGS is not inferior to CDS in terms of technical success. When one procedure is particularly challenging, readily switching to the other could increase technical success.

Non-invasive quantification of human swallowing using a simple motion tracking system.

The number of patients with dysphagia is rapidly increasing due to the ageing of the population. Therefore, the importance of objectively assessing swallowing function has received increasing attention. Videofluoroscopy and videoendoscopy are the standard clinical examinations for dysphagia, but these techniques are not suitable for daily use because of their invasiveness. Here, we aimed to develop a novel, non-invasive method for measuring swallowing function using a motion tracking system, the Kinect v2 sensor. Five males and five females with normal swallowing function participated in this study. We defined three mouth-related parameters and two larynx-related parameters and recorded data from 2.5 seconds before to 2.5 seconds after swallowing onset. Changes in mouth-related parameters were observed before swallowing and reached peak values at the time of swallowing. In contrast, larynx-related parameters showed little change before swallowing and reached peak values immediately after swallowing. This simple swallow tracking system (SSTS) successfully quantified the swallowing process from the oral phase to the laryngeal phase. This SSTS is non-invasive, wireless, easy to set up, and simultaneously measures the dynamics of swallowing from the mouth to the larynx. We propose the SSTS for use as a novel and non-invasive swallowing assessment tool in the clinic.

Non-invasive detection of language-related prefrontal high gamma band activity with beamforming MEG.

High gamma band (>50 Hz) activity is a key oscillatory phenomenon of brain activation. However, there has not been a non-invasive method established to detect language-related high gamma band activity. We used a 160-channel whole-head magnetoencephalography (MEG) system equipped with superconducting quantum interference device (SQUID) gradiometers to non-invasively investigate neuromagnetic activities during silent reading and verb generation tasks in 15 healthy participants. Individual data were divided into alpha (8-13 Hz), beta (13-25 Hz), low gamma (25-50 Hz), and high gamma (50-100 Hz) bands and analysed with the beamformer method. The time window was consecutively moved. Group analysis was performed to delineate common areas of brain activation. In the verb generation task, transient power increases in the high gamma band appeared in the left middle frontal gyrus (MFG) at the 550-750 ms post-stimulus window. We set a virtual sensor on the left MFG for time-frequency analysis, and high gamma event-related synchronization (ERS) induced by a verb generation task was demonstrated at 650 ms. In contrast, ERS in the high gamma band was not detected in the silent reading task. Thus, our study successfully non-invasively measured language-related prefrontal high gamma band activity.

In-Line Reactions and Ionizations of Vaporized Diphenylchloroarsine and Diphenylcyanoarsine in Atmospheric Pressure Chemical Ionization Mass Spectrometry.

We propose detecting a fragment ion (Ph2As(+)) using counter-flow introduction atmospheric pressure chemical ionization ion trap mass spectrometry for sensitive air monitoring of chemical warfare vomiting agents diphenylchloroarsine (DA) and diphenylcyanoarsine (DC). The liquid sample containing of DA, DC, and bis(diphenylarsine)oxide (BDPAO) was heated in a dry air line, and the generated vapor was mixed into the humidified air flowing through the sampling line of a mass spectrometer. Humidity effect on the air monitoring was investigated by varying the humidity of the analyzed air sample. Evidence of the in-line conversion of DA and DC to diphenylarsine hydroxide (DPAH) and then BDPAO was obtained by comparing the chronograms of various ions from the beginning of heating. Multiple-stage mass spectrometry revealed that the protonated molecule (MH(+)) of DA, DC, DPAH, and BDPAO could produce Ph2As(+) through their in-source fragmentation. Among the signals of the ions that were investigated, the Ph2As(+) signal was the most intense and increased to reach a plateau with the increased air humidity, whereas the MH(+) signal of DA decreased. It was suggested that DA and DC were converted in-line into BDPAO, which was a major source of Ph2As(+). Graphical Abstract ᅟ.