[Usefulness of Preoperative Simulation: Skull Base Approach]

Preoperative simulation images creates an accurate visualization of a surgical field. The anatomical relationship of the cranial nerves, arteries, brainstem, and related bony protrusions is important in skull base surgery. However, an operator's intention is unclear for a less experienced neurosurgeon. Three-dimensional(3D)fusion images of computed tomography and magnetic resonance imaging created using a workstation aids precise surgical planning and safety management. Since the simulation images allows to perform virtual surgery, a déjà vu effect for the surgeon can be obtained. Additionally, since 3D surgical images can be used for preoperative consideration and postoperative verification, discussion among the team members is effective from the perspective of surgical education for residents and medical students. Significance of preoperative simulation images will increase eventually.

Combined endoscopic endonasal and transcranial approach for internal carotid artery aneurysms: usefulness and safety of endonasal proximal control

It is necessary to secure both the proximal and distal sides of the parent artery to prevent premature rupture when clipping cerebral aneurysms. Herein, we describe four cases in which the proximal internal carotid artery (ICA), affected by a paraclinoid aneurysm, was secured using an endoscopic endonasal approach. We used various tools, including a surgical video, cadaver dissection picture, artist's illustration, and intraoperative photographs, to elucidate the process. No patient experienced postoperative complications at our institution. Compared to the cervical or cavernous ICA, the ICA adjacent to the clivus (paraclival ICA) can be anatomically safely and easily exposed using an endoscopic endonasal approach because there is no need to consider cerebrospinal fluid leakage or hemorrhage from the cavernous sinus. Securing the proximal side of the parent artery using an endoscopic endonasal approach may be a viable method for clipping selected ICA aneurysms, such as paraclinoid aneurysms especially for upward or outward aneurysms of the C2 portion.

Dynamin-related protein 2 interacts with the membrane-associated methyltransferase domain of plantago asiatica mosaic virus replicase and promotes viral replication

Positive-strand RNA viruses replicate their RNA in the viral replication complex, a spherical structure formed by remodeling of host intracellular membranes. This process also requires the interaction between viral membrane-associated replication proteins and host factors. We previously identified the membrane-associated determinant of the replicase of plantago asiatica mosaic virus (PlAMV), a positive-strand RNA virus of the genus Potexvirus, in its methyltransferase (MET) domain, and suggested that its interaction with host factors is required to establish viral replication. Here we identified Nicotiana benthamiana dynamin-related protein 2 (NbDRP2) as an interactor of the MET domain of the PlAMV replicase by co-immunoprecipitation (Co-IP) and mass spectrometry analysis. NbDRP2 is closely related to the DRP2 subfamily proteins in Arabidopsis thaliana, AtDRP2A and AtDRP2B. Confocal microscopy observation and Co-IP confirmed the interaction between the MET domain and NbDRP2. Also, the expression of NbDRP2 was induced by PlAMV infection. PlAMV accumulation was reduced when the expression of NbDRP2 gene was suppressed by virus-induced gene silencing. In addition, PlAMV accumulation was reduced in protoplasts treated with dynamin inhibitor. These results indicate a proviral role of the interaction of NbDRP2 with the MET domain in PlAMV replication.

Computational Fluid Dynamics Analysis Features in Aneurysm Development in Rats

The investigation of how to control the development and growth of cerebral aneurysms is important for the prevention of subarachnoid hemorrhage. Although there have been several types of research studies on computational fluid dynamics (CFD) analysis of brain aneurysm development and growth, there has been no unified interpretation of the CFD analysis results. The purpose of this study is to clarify the characteristics of CFD analysis results related to the development of cerebral aneurysms using an animal model. Nineteen rat models of cerebral aneurysms were created, and the CFD analysis results between the cerebral aneurysm group [n = 10; the aneurysm was observed on magnetic resonance angiography (MRA) within 10 weeks after aneurysm induction surgery] and the nonaneurysm group (n = 9) were compared. All aneurysms were confirmed on the proximal segment of the left cerebral artery (P1), and the cross-sectional area and curvature of the left P1 were evaluated together. In the cerebral aneurysm group, there was a decrease in wall shear stress (WSS) that is consistent with the location of the aneurysm compared to the nonaneurysm group. The cross-sectional area of the left P1 gradually increased in the aneurysm group but not in the nonaneurysm group. The mean curvature in the entire left P1 was higher in the aneurysm group than in the nonaneurysm group. This study revealed that the development of cerebral aneurysms is due to changes in vascular morphology, namely, an increase in vessel diameter and a high curvature, and a decreased WSS consistent with the site of aneurysm development using this animal model.

Microbleeds Due to Reperfusion Enhance Early Seizures after Carotid Ligation in a Rat Ischemic Model

Impaired reperfusion in ischemic brain disease is a condition that we are increasingly confronted with owing to recent advances in reperfusion therapy. In the present study, rat models of reperfusion were investigated to determine the causes of acute seizures using magnetic resonance imaging (MRI) and histopathological specimens. Rat models of bilateral common carotid artery ligation followed by reperfusion and complete occlusion were created. We compared the incidence of seizures, mortality within 24 h, MRI, and magnetic resonance spectroscopy (MRS) to evaluate ischemic or hemorrhagic changes and metabolites in the brain parenchyma. In addition, the histopathological specimens were compared with those observed on MRI. In multivariate analysis, the predictive factors of mortality were seizure (odds ratios (OR), 106.572), reperfusion or occlusion (OR, 0.056), and the apparent diffusion coefficient value of the striatum (OR, 0.396). The predictive factors of a convulsive seizure were reperfusion or occlusion (OR, 0.007) and the number of round-shaped hyposignals (RHS) on susceptibility-weighted imaging (SWI) (OR, 2.072). The incidence of convulsive seizures was significantly correlated with the number of RHS in the reperfusion model. RHS on SWI was confirmed pathologically as microbleeds in the extravasation of the brain parenchyma and was distributed around the hippocampus and cingulum bundle. MRS analysis showed that the N-acetyl aspartate level was significantly lower in the reperfusion group than in the occlusion group. In the reperfusion model, RHS on SWI was a risk factor for convulsive seizures. The location of the RHS also influenced the incidence of convulsive seizures.

Transcranial electrical stimulation technique for induction of unilateral motor evoked potentials

OBJECTIVE

Transcranial electrical stimulation motor evoked potentials (TES-MEP) are widely used to monitor motor function; however, broad current spread and induced body movement are limitations of this technique. We herein report a localized stimulation technique for TES-MEP that induces unilateral MEP responses.

METHODS

The stimulation of C1(+)-C4(-) or C2(+)-C3(-) was performed to induce right- or left-sided muscle contraction, respectively, in 70 patients. Electromyography was recorded by placing electrodes on the bilateral abductor pollicis brevis (APB) and abductor hallucis (AH) muscles. Stimulation conditions were regulated in the range to induce unilateral muscle contractions contralateral to the anodal stimulation. The thresholds and amplitudes of TES-MEP were retrospectively analyzed.

RESULTS

The thresholds of APB were lower than those of AH in 47 patients, AH thresholds were lower than those of APB in 6 patients, and both APB and AH started to respond at the same intensity in 15 patients. This technical stimulation induced contralateral limb contractions with a suprathreshold stimulation of 129.4 ± 35.6 mA (mean ± standard deviation) in 68 patients (97%). Amplitudes in the suprathreshold stimulation of APB and AH responses were 727.5 ± 695.7 and 403.3 ± 325.7 μV, respectively.

CONCLUSIONS

The C1(+)-C4/C2(+)-C3(-) stimulation in TES-MEP enables a localized stimulation to induce unilateral MEP responses.

SIGNIFICANCE

Our stimulation technique enables the stable and safe monitoring of unilateral limbs, and contributes to the reliable monitoring of motor function in neurosurgery.

A practical protocol for high-spatial-resolution magnetic resonance angiography for cerebral arteries in rats

BACKGROUND

Magnetic resonance angiography (MRA) is an important tool in rat models of cerebrovascular disease. Although MRA has long been used in rodents, the image quality is typically not as high as that observed in clinical practice. Moreover, studies on MRA image quality in rats are limited. This study aimed to develop a practical high-spatial-resolution MRA protocol for imaging cerebral arteries in rats.

NEW METHOD

We used the "half position method" regarding coil placement and modified the imaging parameters and image reconstruction method. We applied this new imaging method to measure maturation-related signal changes on rat MRAs.

RESULTS

The new practical high-spatial-resolution MRA imaging protocol obtained a signal intensity up to 3.5 times that obtained using a basic coil system, simply by modifying the coil placement method. This method allowed the detection of a gradual decrease in the signal in cerebral vessels with maturation.

COMPARISON WITH EXISTING METHODS

A high-spatial-resolution MRA for rats was obtained with an imaging time of approximately 100 min. Comparable resolution and image quality were obtained using the new protocol with an imaging time of 30 min CONCLUSIONS: The new practical high-spatial-resolution MRA protocol can be implemented simply and successfully to achieve high image quality with an imaging time of approximately 30 min. This protocol will benefit researchers performing MRA imaging in cerebral artery studies in rats.

Validity of preoperative screening before open-heart surgery in reduction of perioperative ischemic stroke

OBJECTIVES

Cerebrovascular event after open-heart surgery is a critical complication and contributes to poor prognosis, including increased mortality. The purpose of this study is to investigate the appropriate preoperative risk assessment and monitoring for reducing the risk of ischemic stroke after open-heart surgery.

MATERIALS AND METHODS

184 patients who underwent surgery for valvular heart disease were included in this study. Near-infrared oxygen saturation monitoring (INVOS system) was performed during open-heart surgery. For the purpose of perioperative stroke risk assessment, we evaluated the clinical and radiological factors of the group that underwent preoperative consultation and the group that did not, and of the patients with and without postoperative ischemic stroke.

RESULTS

Preoperative consultation was performed in 60 cases. Large vessel steno-occlusive disease was found in nine cases, of which three had undergone revascularization surgery. Cerebral infarction developed in four cases, all of which had no large vessel steno-occlusive disease. There was no significant association between the development of postoperative ischemic stroke and presence of large vessel steno-occlusive disease. Preoperative baseline INVOS value was significantly low in the ischemic stroke group (49.5 ± 12.5) compared to the non-ischemic stroke group (66.8 ± 10.0), (P = 0.012).

CONCLUSIONS

In open-heart surgery for valvular heart disease, low preoperative baseline INVOS values were associated with cerebral ischemic stroke after surgery. The combination of appropriate preoperative screening for large vessel steno-occlusive disease and measurement of INVOS could be used as a simple and useful method in screening for the risk of ischemic stroke after open-heart surgery.

Effect of Early Surgical Intervention for Brain Tumors Associated with Epilepsy on the Improvement in Memory Performance

We evaluated the effect of early surgical intervention on the change in memory performance of patients with low-grade brain tumors associated with epilepsy. Twenty-three adult patients with low-grade brain tumors and epilepsy who underwent surgery at our institution between 2010 and 2019 were included. The Wechsler Memory Scale-Revised (WMS-R) was used to assess cognitive memory performance. Memory performance before and after surgery was retrospectively evaluated. In addition, the relationships among preoperative memory function, postoperative seizure outcome, preoperative seizure control, temporal lobe lesion, and change in memory function were examined. There were statistically significant improvements from median preoperative to postoperative WMS-R subscale scores for verbal memory, general memory, and delayed recall (p<0.001, p<0.001, and p=0.0055, respectively) regardless of preoperative sores and tumor location. Good postsurgical seizure control was associated with significant improvements in postoperative WMS-R performance. Our results indicated that early surgical intervention might improve postoperative memory function in patients with low-grade brain tumors and epilepsy.

Macrohistory of Moyamoya Disease Analyzed Using Artificial Intelligence

INTRODUCTION

Moyamoya disease is characterized by progressive stenotic changes in the terminal segment of the internal carotid artery and the development of abnormal vascular networks called moyamoya vessels. The objective of this review was to provide a holistic view of the epidemiology, etiology, clinical findings, treatment, and pathogenesis of moyamoya disease. A literature search was performed in PubMed using the term "moyamoya disease," for articles published until 2021.

RESULTS

Artificial intelligence (AI) clustering was used to classify the articles into 5 clusters: (1) pathophysiology (23.5%); (2) clinical background (37.3%); (3) imaging (13.2%); (4) treatment (17.3%); and (5) genetics (8.7%). Many articles in the "clinical background" cluster were published from the 1970s. However, in the "treatment" and "genetics" clusters, the articles were published from the 2010s through 2021. In 2011, it was confirmed that a gene called Ringin protein 213 (RNF213) is a susceptibility gene for moyamoya disease. Since then, tremendous progress in genomic, transcriptomic, and epigenetic profiling (e.g., methylation profiling) has resulted in new concepts for classifying moyamoya disease. Our literature survey revealed that the pathogenesis involves aberrations of multiple signaling pathways through genetic mutations and altered gene expression.

CONCLUSION

We analyzed the content vectors in abstracts using AI, and reviewed the pathophysiology, clinical background, radiological features, treatments, and genetic peculiarity of moyamoya disease.

Effects of polarity of bipolar sensorimotor direct cortical stimulation on intraoperative motor evoked potentials

OBJECTIVE

The present study investigated the effects of the stimulus polarity and location of motor evoked potential (MEP) to establish a stimulation protocol.

METHODS

Nineteen patients who intraoperatively underwent MEP in bipolar direct cortical stimulation were enrolled in the present study. Somatosensory evoked potentials (SEP) of the contralateral median nerve stimulation were recorded to determine stimulation sites. MEP was performed under two settings in all patients: 1. Anodal bipolar stimulation: an anode on the precentral gyrus and a cathode on the postcentral gyrus, 2. Cathodal bipolar stimulation: a cathode on the precentral gyrus and an anode on the postcentral gyrus. MEP amplitudes and the coefficient of variation (CV) at a stimulation intensity of 25 mA and the thresholds of induced MEP were compared between the two settings.

RESULTS

An electrical stimulation at 25 mA induced a significantly higher amplitude in cathodal bipolar stimulation than in anodal bipolar stimulation. Cathodal bipolar stimulation also showed significantly lower thresholds than anodal stimulation. CV did not significantly differ between the two groups.

CONCLUSIONS

These results indicate that cathodal bipolar stimulation is superior to anodal bipolar stimulation for intraoperative MEP monitoring.

SIGNIFICANCE

MEP in cathodal bipolar cortical stimulation may be used in a safe and useful evaluation method of motor fiber damage that combines sensitivity and specificity.

Additional Revascularization Using Multiple Burr Holes for PCA Involvement in Moyamoya Disease

In specific cases of moyamoya disease (MMD), posterior cerebral artery (PCA) stenosis can develop after treatment of the anterior circulation and require additional revascularization. Here, we report two cases that underwent additional posterior indirect revascularization with multiple burr holes for PCA involvement after bilateral revascularization treatment of the anterior circulation. They presented with transient ischemic attack even after bilateral superficial temporal artery-middle cerebral artery bypass, and magnetic resonance angiography (MRA) showed that PCA stenosis had worsened. Indirect revascularization with multiple burr holes using Benz-marked skin incisions was performed. After surgery, the symptoms improved without perioperative complications, and cerebral angiography showed collateral circulation via the burr hole. Indirect revascularization for MMD is often combined with direct revascularization, and there are only a few reports on the use of multiple burr hole surgery alone. In addition, there are few reports of posterior circulation, despite the emphasis on the importance of PCA involvement in MMD. Indirect revascularization with multiple burr holes alone can be performed in multiple areas and applied to patients who cannot undergo direct revascularization using the occipital artery. The procedure is simple and less invasive than traditional direct revascularization procedures. Therefore, it can be effective, especially in pediatric cases of MMD with PCA involvement.

Aging-associated inflammation and fibrosis in arachnoid membrane

Background

The physiological and pathological significance of the arachnoid membrane (AM) is still unknown. In this study, we investigated various characteristics of the AM, focusing on the influence of inflammation and fibrosis.

Methods

Small pieces of AM sample were obtained during neurosurgical procedures from 74 cases. The clinical and pathological characteristics of the hyperplastic AM group (≥ 50 μm) and the non-hyperplastic AM group (< 50 μm) were compared. Then, potential correlations between AM thickness and clinical characteristics were analyzed. Moreover, VEGFα, TGFβ, and TGFα levels were quantitated by real time PCR. Then, the potential correlations between AM thickness and these inflammatory or anti-inflammatory markers, and the influence of the original disease were calculated.

Results

The median age of the patients in hyperplastic AM group was significantly older than that of the non-hyperplastic AM group. Moreover, the number of fibroblasts, CD68⁺ cells, CD86⁺ cells, and CD206⁺ cells in the hyperplastic AM group was significantly higher than that in the non-hyperplastic AM group. The AM thickness was significantly correlated to age and number of fibroblasts, CD68⁺ cells, CD86⁺ cells, and CD206⁺ cells. The thickness of the AM was significantly correlated to the messenger RNA expression levels of VEGFα (ρ = 0.337), and the VEGFα expression levels were significantly correlated with TGFβ and TNFα.

Conclusions

The AM hyperplasia was influenced by aging and could be a result of inflammation and fibrosis through cytokine secretion from the inflammatory cells and fibroblasts in the AM.

COVID-19 infection in Hokkaido, Japan might depend on the viscosity of atmospheric air

BACKGROUND

The large number of people infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has plunged the world into fear in recent times. In Japan, 18,769 novel coronavirus disease 2019 (COVID-19) cases have been reported as of June 30, 2020. This study aimed to assess whether cluster infection prevention is possible by evaluating the association between viral transmission and meteorological factors.

METHODS

This study included 1263 people who were successively diagnosed with COVID-19 in Hokkaido, Japan between January 24, 2020 and June 30, 2020. After obtaining the values from the Japanese Meteorological Agency, the average scores of air temperature and humidity were calculated and compared with COVID-19 reproduction numbers, and the association between COVID-19 incidence or reproduction number and meteorological factors was assessed.

RESULTS

The COVID-19 reproduction number in Hokkaido had three peaks that came several days before the surge in COVID-19 cases. The peaks are indicative of cluster infections. There was a strong negative correlation between the kinematic viscosity of atmospheric air and the reproduction number.

DISCUSSION AND CONCLUSION

Analysis of the reproduction number is important for predicting or suppressing COVID-19 infection clusters. The authors found a strong association between meteorological factors, such as kinematic viscosity of atmospheric air and the incidence of COVID-19 infection. Meteorological forecasts could provide foreknowledge about COVID-19 infection clusters in the future.

Preoperative Prediction of Communication Difficulties during Awake Craniotomy in Glioma Patients: A Retrospective Evaluation of 136 Cases at a Single Institution

Awake craniotomy has been widely performed in patients with glioma in eloquent areas to minimize postoperative brain dysfunction. However, neurological examination in awake craniotomy is sometimes problematic due to communication difficulties during the intraoperative awake period. We evaluated preoperative predictors of these difficulties in awake craniotomy for patients with glioma. In all, 136 patients with glioma who underwent awake craniotomy at our institution between January 2012 and January 2020 were retrospectively evaluated. Patients were divided into two groups (appropriately awake group and inappropriately awake group) depending on their state during the intraoperative awake period, and the relationship between communication difficulties in awake craniotomy and both clinical and radiological characteristics were assessed. The appropriately awake group included 110 patients, and the inappropriately awake group included 26 patients. Reasons for inclusion in the inappropriately awake group were insufficient wakefulness in 15 patients, restless state in 6, and intraoperative seizures in 5. In multivariate analysis, the likelihood of being inappropriately awake was inversely correlated with preoperative seizures (odds ratio [OR], 0.23; 95% confidence interval [CI], 0.06–0.89; p = 0.033) and positively correlated with left-sided lesions (OR, 7.31; 95% CI, 1.54–34.62; p = 0.012). Both lack of preoperative seizures and left-sided lesions were identified as risk factors for intraoperative difficulties in awake craniotomy for patients with glioma. Understanding these risk factors may lead to more appropriate determination of eligibility for awake craniotomy.

Recurrence Interval Within 1 Year Leads to Death in Patients with Grade 2 Meningioma

OBJECTIVE

Grade 2 meningioma is more likely to recur than grade 1 meningioma. Recurrence decreases overall survival in patients with grade 2 meningioma. However, the clinical course of grade 2 meningioma with several repeated recurrences is poorly understood. The purpose of this study was to clarify the clinical characteristics of grade 2 meningioma with repeated recurrences.

METHODS

This study included 28 patients with grade 2 meningioma treated at our institution from January 1994 to December 2017. The relationship between survival and factors including age, sex, number of recurrences, malignant transformation, radiation therapy, tumor location, MIB-1 labeling index, Simpson grade, Karnofsky Performance Status, and surgical interval were analyzed.

RESULTS

The average age at the initial operation was 53.4 years. The number of recurrences was 3.7 times on average during the follow-up of 113.9 months after the initial operation. An increasing number of recurrences resulted in shortening of the surgical interval, increase in the MIB-1 labeling index, and decrease in Karnofsky Performance Status. In fatal cases, the average surgical interval before death was approximately 1 year. Three factors were related to poor prognosis: number of recurrences (odds ratio, 1.620; P = 0.030), malignant transformation (odds ratio, 10.625; P = 0.019), and high MIB-1 labeling index (odds ratio, 1.089; P = 0.044).

CONCLUSIONS

Shortening of the surgical interval within 1 year because of multiple recurrences led to death in patients with grade 2 meningioma. Malignant transformation was the most potent among the poor prognostic factors.

Ischemic Tolerance Evaluated by Computed Tomography Perfusion during Balloon Test Occlusion

OBJECTIVES

Balloon test occlusion (BTO) is performed to evaluate ischemic tolerance for large and giant cerebral aneurysms and head and neck tumors that may require parent artery occlusion. However, ischemic tolerance for the temporary test occlusion does not always guarantee a tolerance for permanent occlusion. In this study, we evaluated the utility of computed tomography (CT) perfusion during BTO to quantify ischemic tolerance for detecting delayed ischemic stroke.

MATERIALS AND METHODS

Forty-one patients who underwent BTO for the internal carotid artery were included. The correlations between the parameters of CT perfusion and collateral angiographic appearance or stump pressure during BTO were evaluated. The cerebral blood flow (CBF), cerebral blood volume, mean transit time (MTT), and time to peak (TTP) were obtained through CT perfusion, and the asymmetry ratios were determined. Collateral angiographic appearances were categorized into 5 grades (0-4).

RESULTS

The collateral angiographic appearance showed moderate correlations with CBF, MTT, and TTP that was significant. Of these, the absolute value of the correlation coefficient was the highest for MTT. MTT also showed a moderate correlation with stump pressure. CBF and MTT were significantly different between the poor collateral group (grades 2 and 3) and the good collateral group (grade 4). Based on the MTT, the good collateral group was identified with high sensitivity (75.0%) and specificity (81.2%).

CONCLUSIONS

In BTO, the MTT obtained through CT perfusion showed a correlation with collateral angiographic appearance and stump pressure. Thus, the MTT might be useful to quantify ischemic tolerance for detecting delayed ischemic stroke.

Prevention of neointimal hyperplasia induced by an endovascular stent via intravenous infusion of mesenchymal stem cells

OBJECTIVE

In-stent restenosis after percutaneous transluminal angioplasty and stenting (PTAS) due to neointimal hyperplasia is a potential cause of clinical complications, including repeated revascularization and ischemic events. Neointimal hyperplasia induced by an inflammatory response to the stent strut may be a possible mechanism of in-stent restenosis. Intravenous infusion of bone marrow-derived mesenchymal stem cells (MSCs) has been reported to show therapeutic efficacy for cerebral stroke, presumably by an antiinflammatory effect. This study aimed to determine whether MSCs can reduce or prevent neointimal hyperplasia induced by an endovascular stent.

METHODS

In this study, two types of bare metal stents were deployed using a porcine (mini-pig) model. One stent was implanted in the common carotid artery (CCA), which is considered quite similar to the human CCA, and the other was inserted in the superficial cervical artery (SCA), which is similar in size to the human middle cerebral artery. Angiographic images, intravascular ultrasound (IVUS) imaging, and microscopic images were used for analysis.

RESULTS

Angiographic images and IVUS studies revealed that intravenous infusion of MSCs immediately after deployment of stents prevented in-stent stenosis of the CCA and SCA. Histological analysis also confirmed that inflammatory responses around the stent struts were reduced in both the stented CCA and SCA in the mini-pig.

CONCLUSIONS

Intravenous infusion of MSCs inhibited the inflammatory reaction to an implanted stent strut, and prevented progressive neointimal hyperplasia in the stented CCA and SCA in a porcine model. Thus, MSC treatment could attenuate the recurrence of cerebral ischemic events after stenting.

Rare Case of Concurrent Glossopharyngeal and Trigeminal Neuralgia, in Which Glossopharyngeal Neuralgia was Possibly Induced by Postoperative Changes Following Microvascular Decompression for Trigeminal Neuralgia

BACKGROUND

Glossopharyngeal neuralgia (GPN) and trigeminal neuralgia (TN) can result from mechanical stimulation of the glossopharyngeal nerve (GPNv) and trigeminal nerve (TNv) by blood vessels. TN can cause severe pain in the orofacial region, whereas GPN manifests as pain in the tongue, throat, tonsil, and ear. Although these 2 neuralgias can occur concurrently, concurrence of recurrent TN and GPN that develops postoperatively has not been previously described.

CASE DESCRIPTION

A 68-year-old male complained of right glossalgia and pain in the pharynx radiating to the right auricular area. The patient had previously undergone microvascular decompression (MVD) for right TN. Medication and intraoral xylocaine spray did not relieve the symptoms. An oral surgeon was unable to find any disease related to the glossalgia. The anesthesiologist pointed out that the symptoms could be from partial recurrence of the TN because the patient also complained of pain in the inferior alveolus. Magnetic resonance angiography indicated that the right GPNv seemed to be compressed by the right posterior inferior cerebellar artery (PICA); hence, MVD for both GPN and TN was performed. Intraoperatively, the right PICA was found to be adherent to the GPNv because of the thickened arachnoid membrane and was subsequently detached. The TNv was also examined, but only a Teflon ball was found, which was detached from the TNv. The GPN disappeared postoperatively, although TN persisted after the second operation.

CONCLUSIONS

GPN can result from adhesions between the GPNv and arachnoid membrane following previous MVD.

Influence of Inflammatory Disease on the Pathophysiology of Moyamoya Disease and Quasi-moyamoya Disease

Moyamoya disease is a unique cerebrovascular disease that is characterized by progressive bilateral stenotic alteration at the terminal portion of the internal carotid arteries. These changes induce the formation of an abnormal vascular network composed of collateral pathways known as moyamoya vessels. In quasi-moyamoya disease, a similar stenotic vascular abnormality is associated with an underlying disease, which is sometimes an inflammatory disease. Recent advances in moyamoya disease research implicate genetic background and immunological mediators, and postulate an association with inflammatory disease as a cause of, or progressive factor in, quasi-moyamoya disease. Although this disease has well-defined clinical and radiological characteristics, the role of inflammation has not been rigorously explored. Herein, we focused on reviewing two main themes: (1) molecular biology of inflammation in moyamoya disease, and (2) clinical significance of inflammation in quasi-moyamoya disease. We have summarized the findings of the former theme according to the following topics: (1) inflammatory biomarkers, (2) genetic background of inflammatory response, (3) endothelial progenitor cells, and (4) noncoding ribonucleic acids. Under the latter theme, we summarized the findings according to the following topics: (1) influence of inflammatory disease, (2) vascular remodeling, and (3) mechanisms gleaned from clinical cases. This review includes articles published up to February 2019 and provides novel insights for the treatment of the moyamoya disease and quasi-moyamoya disease.

[Possible Segmental Arterial Mediolysis Associated with Intraperitoneal Hemorrhage in the Acute Stage of Subarachnoid Hemorrhage:A Case Report]

Segmental arterial mediolysis(SAM)is a rare non-inflammatory and non-atherosclerotic arteriopathy associated with the occurrence of multiple aneurysms such as intracranial and intraperitoneal aneurysms. We report a case of intraperitoneal hemorrhage that occurred during the acute stage of subarachnoid hemorrhage(SAH). An 82-year-old woman presented with a sudden onset of loss of consciousness with a diagnosis of SAH. Digital subtraction angiography demonstrated two consecutive vertebral artery-posterior inferior cerebellar artery aneurysms. The larger aneurysm, which seemed to be ruptured, was successfully treated by coil embolization. On the 9th day after the onset of SAH, she developed aphasia secondary to the cerebral vasospasm. After selective intra-arterial infusion of fasudil hydrochloride, she was observed to maintain elevated systolic blood pressure. Her aphasia improved; however, on the 14th day, she suddenly developed hemorrhagic shock. An abdominal computed tomography scan demonstrated intraperitoneal hemorrhage secondary to a ruptured fusiform aneurysm of the right gastroepiploic artery. The lesion was successfully treated by coil embolization, although she became bedridden. Although a histopathological examination was not performed, her clinical, radiological, and serological presentation met the criteria of the clinical diagnosis of SAM. Elevated systolic blood pressure and excessive release of catecholamines in the acute stage of SAH might have caused the intraperitoneal hemorrhage. Non-saccular ruptured intracranial aneurysms should be considered among the differential diagnoses of SAM. In such cases, identifying and monitoring intraperitoneal aneurysms might be useful for earlier diagnosis and treatment of SAM, especially in the acute stage after SAH.

Ruptured intranidal aneurysm of an arteriovenous malformation diagnosed by delay alternating with nutation for tailored excitation (DANTE)-prepared contrast-enhanced magnetic resonance imaging

This case report describes the usefulness of delay alternating with nutation for tailored excitation (DANTE)-prepared, contrast-enhanced magnetic resonance imaging (CE-MRI) for detecting the rupture site of an arteriovenous malformation (AVM). A ruptured intranidal aneurysm was confirmed histopathologically. Accurate non-invasive information about the possible rupture site of an AVM is critical for optimal treatment and evaluation. Vessel wall enhancement visualized by DANTE-prepared CE-MRI may be a useful tool for providing information about changes in inflammatory status and vulnerability to further developments.

Effectiveness of intraoperative visual evoked potential in avoiding visual deterioration during endonasal transsphenoidal surgery for pituitary tumors

Postoperative visual function is a major concern in transsphenoidal surgery (TSS). Although several reports have demonstrated the importance of visual evoked potential (VEP) monitoring during TSS, the usefulness of VEP monitoring have been controversial because of its reproducibility. Efficacy of VEP was analyzed in 20 consecutive cases of patients who underwent endoscopic endonasal TSS surgery. We adapted a high-power light-emitting diode stimulator with electroretinography using venous anesthesia. In addition, we used black shield patch and braided codes to obtain reproducible VEP amplitudes. Stable and reproducible VEP waveforms were obtained in 38 of 39 eyes (97.4%) before surgery. Fifteen eyes had deteriorated VEP amplitude during operation, and nine eyes had improved VEP amplitude at the end of surgery, and six eyes had not improved VEP amplitude. But no postoperative visual impairment was observed in all cases by temporary halting the surgical manipulation when the VEP was deteriorated. In conclusion, VEP monitoring could be a warning sign to avoid postoperative visual dysfunction. We recommend VEP as a routine monitoring in TSS.

Utility of state-level influenza disease burden and severity estimates to investigate an apparent increase in reported severe cases of influenza A(H1N1) pdm09 - Arizona, 2015-2016

The Arizona Department of Health Services identified unusually high levels of influenza activity and severe complications during the 2015-2016 influenza season leading to concerns about potential increased disease severity compared with prior seasons. We estimated state-level burden and severity to compare across three seasons using multiple data sources for community-level illness, hospitalisation and death. Severity ratios were calculated as the number of hospitalisations or deaths per community case. Community influenza-like illness rates, hospitalisation rates and mortality rates in 2015-2016 were higher than the previous two seasons. However, ratios of severe disease to community illness were similar. Arizona experienced overall increased disease burden in 2015-2016, but not increased severity compared with prior seasons. Timely estimates of state-specific burden and severity are potentially feasible and may provide important information during seemingly unusual influenza seasons or pandemic situations.

Pressure-induced stacking disorder in boehmite

The structure of an aluminum layered hydroxide, boehmite (γ-AlOOH), as a function of pressure was studied by using in situ synchrotron X-ray and neutron diffraction. Peak broadening, which is only found for hkl (h ≠ 0) peaks in the X-ray diffraction patterns, is explained by stacking disorder accompanying a continuously increasing displacement of the AlO6 octahedral layer along the a-axis. This finding could be the first experimental result for pressure-induced stacking disorder driven by continuous layer displacement. The magnitude of the layer displacement was estimated from the X-ray scattering profile calculation based on the stacking disordered structure model. Hydrogen bond geometries of boehmite, obtained by structure refinements of the observed neutron diffraction patterns for the deuterated sample up to 10 GPa, show linearly approaching O-D covalent and DO hydrogen bond distances and they merge below 26 GPa. Pressure-induced stacking disorder makes the electrostatic potential of hydrogen bonds asymmetric, yielding less chance for proton-tunnelling.

Interdisciplinary Prevention and Management of Wound-Related Complications in Extracranial-to-Intracranial Bypass Surgery

Extracranial-to-intracranial (EC-IC) bypass surgery may be necessary in patients with moyamoya disease and other ischemic conditions. However, there is a potential risk of wound-related complications in some cases. In this study, we report our approach to the prevention of wound-related complications in EC-IC bypass. Technical considerations and pitfalls of surgery are also discussed. This study included 89 patients with ischemic-onset moyamoya disease and atherosclerotic disease who underwent 108 superficial temporal artery (STA)-to-middle cerebral artery bypass procedures. Our study emphasized 3 major features. First, 3-dimensional simulation imaging was used to confirm STA anatomy. Second, the STA was meticulously dissected on the epigaleal layer to protect the galeal layer. Third, scalp skin ischemia was taken into consideration at each step until skin closure. There was no neurologic morbidity or mortality in this series. There were 2 cases of major wound-related complications requiring plastic surgical intervention, and 4 cases of minor complications that were treated conservatively. In major complication cases, the scalp defect was treated with pedicle flap reconstruction. In EC-IC bypass surgery, interdisciplinary management involving neurosurgery, plastic surgery, and radiology should reduce wound-related complications and achieve safe surgery.

Development of moyamoya disease after non-herpetic acute limbic encephalitis: A case report

We report a case of moyamoya disease (MMD), which developed after non-herpetic acute limbic encephalitis (NHALE) associated with anti-leucine-rich glioma-inactivated 1 (LGI1) antibody. The patient's mother had a history of MMD. No vascular lesions were identified at the time of the NHALE. Nine years later, the patient visited our hospital due to memory disturbances and repeated transient ischemic attacks affecting the right limb. Diffusion-weighted magnetic resonance imaging revealed scattered areas of signal hyperintensity, and the patient was ultimately diagnosed with MMD based on angiography. Revascularization surgery was performed on the left side, where cerebral blood flow was impaired on ¹²³I-N-isopropyl-p-iodoamphetamine single photon emission computed tomography. Postoperatively, the patient was discharged with a normal neurological examination. NHALE associated with LGI1 antibodies is an autoimmune disease. Although autoimmune disease is the most frequent finding other than atherosclerosis in quasi-MMD, this is the first report of NHALE associated with anti-LGI1 antibodies mimicking quasi-MMD. Inflammation and angiogenesis may contribute to the development of MMD, in addition to genetic background.

Frequency-Domain Multiplexing Readout with a Self-Trigger System for Pulse Signals from Kinetic Inductance Detectors

We present the development of a frequency-domain multiplexing readout of kinetic inductance detectors (KIDs) for pulse signals with a self-trigger system. The KIDs consist of an array of superconducting resonators that have different resonant frequencies individually, allowing us to read out multiple channels in the frequency domain with a single wire using a microwave-frequency comb. The energy deposited to the resonators break Cooper pairs, changing the kinetic inductance and, hence, the amplitude and the phase of the probing microwaves. For some applications such as X-ray detections, the deposited energy is detected as a pulse signal shaped by the time constants of the quasiparticle lifetime, the resonator quality factor, and the ballistic phonon lifetime in the substrate, ranging from microseconds to milliseconds. A readout system commonly used converts the frequency-domain data to the time-domain data. For the short pulse signals, the data rate may exceed the data transfer bandwidth, as the short time constant pulses require us to have a high sampling rate. In order to overcome this circumstance, we have developed a KID readout system that contains a self-trigger system to extract relevant signal data and reduces the total data rate with a commercial off-the-shelf FPGA board. We have demonstrated that the system can read out pulse signals of 15 resonators simultaneously with about 10 Hz event rate by irradiating α particles from 241 Am to the silicon substrate on whose surface aluminum KID resonators are formed.

Abstract P2-01-08: Enumeration of heterogeneous circulating tumor cells (CTCs) using size-based method in early, and metastatic, breast cancer patients

Background

The detection of circulating tumor cells (CTCs) in peripheral blood is an independent predictor of the efficacy of systemic therapy, and also a prognostic marker for patients with metastatic breast cancer. One of the main methods to detect CTCs is CellSearch system, which uses immune-magnetic separation followed by immunocytochemistry. A microdevice (CTChip from ClearCell system) can capture and enumerate CTCs based on distinctive physiological differences (size and deformability) between cancer cells and blood cells. CTChip thus obtains a larger CTC yield than affinity-based separation, which enriches a particular subgroup of cells expressing EpCAM. In this study, we enumerate CTCs in peripheral blood from early and metastatic breast cancer patients using a size-based method.

Patients and methods

We examined blood samples from a total of 18 early and metastatic breast cancer patients, after obtaining written informed consent. Blood samples were taken in sodium EDTA tubes after discarding the first 1ml of blood from the syringe. Two ml blood samples were applied to CTChip (ClearCell system), and CTCs were eventually trapped in the microwells of the CTChip. Trapped cells were analyzed by immunocytochemistry with monoclonal antibodies specific for leukocytes (CD45) and epithelial cells (CK8/18), along with 4',6-diamidino-2-phenylindole (DAPI) for nuclei: CK8/18-positive, DAPI-positive and CD45-negative cells more than 10 μm in diameter were defined as CTCs. Eight patients were examined using both the CTChip and CellSearch system to compare the yield of CTCs.

Results

Of 18 patients, 6 were de novo stage IV, 6 were recurrent and 6 were early stage breast cancer patients. Of primary tumors, 8 were HER2- and ER and/or PR +, 6 were HER2-and ER- and PR-, 3 were HER2+ and ER and/or PR +, and one was HER2+ and ER- and PR-. Using CTChip, detected CTCs ranged from 3 - 107 cells/2 ml in all cases: 3 - 83 for early stage, 19 - 156 for stage IV and 21 - 146 for recurrent. The number of CTCs found in recurrent patients tended to be higher than in early stage patients. Size-based method using CTChip clearly showed high sensitivity compared with the CellSearch system, which detected CTCs in only 2 cases out of 8. In analysis by immunochemistry, we found CK-negative, CD45-negative and DAPI positive cells with larger diameter (&gt;16 μm) than CK-positive CTCs in most patients, and the numbers were higher in stage IV (8.5 cells of median value) and recurrent (13 cells) patients than in early stage patients (1.5 cells). Our study suggested that CK-negative large cells might be CTCs with epithelial–mesenchymal transition (EMT).

Conclusion

This size-based technology enables us to capture CTCs regardless of EpCAM expression. Enumerated CTCs varied in size and positivity of CK8/18, suggesting the heterogeneity of CTCs. Further research, especially focusing on EMT will be crucial to understand the key mechanism of metastasis and drug resistance.

Citation Format: Tozuka K, Nagai SE, Kubo K, Komatsu K, Takai K, Inoue K, Matsumoto H, Hayashi Y, Tsuboi M, Yamada Y, Wang X, Suganuma M. Enumeration of heterogeneous circulating tumor cells (CTCs) using size-based method in early, and metastatic, breast cancer patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-01-08.

Digital Polymerase Chain Reaction Quantification of SERPINA1 Predicts Prognosis in High-Grade Glioma

BACKGROUND

SERPINA1 plays an anti-inflammatory role in protecting tissues from proteolytic mechanisms. SERPINA1 is positive in gliomas by immunohistochemical analysis; however, the role of SERPINA1, including the relationship with prognosis, has been uncertain. In recent years, digital polymerase chain reaction (PCR) has provided ultra-sensitive assessment of messenger RNA expression from formalin-fixed paraffin-embedded (FFPE) tissues.

OBJECTIVE

In this study, we quantitatively determined the expression of SERPINA1 in high-grade gliomas (HGGs) using digital PCR, and we analyzed its relationship with prognosis.

METHODS

Twenty-nine FFPE surgical samples from patients with HGGs (7 of World Health Organization [WHO] grade III and 22 of WHO grade IV), and human glioblastoma cell lines, U87 and U118, were used for analysis. A qualitative assessment using immunostaining and quantitative assessment using digital PCR were performed to assess the expression of SERPINA1.

RESULTS

The expression of SERPINA1 was demonstrated in glioma tissues and glioblastoma multiforme cell lines by immunostaining. Digital PCR analysis showed that SERPINA1 was expressed in 14.3% and 63.6% of the tissues from patients with grade III and grade IV HGG, respectively (P = 0.035). The median overall survival of 38.8 months in the low SERPINA1 expression group was longer than that of 15.3 months in the high expression group (P = 0.030).

CONCLUSIONS

The frequency and the amount of SERPINA1 expression were higher in grade IV than in grade III HGGs. The high expression of SERPINA1 indicates a poor prognosis of HGGs.

Effectiveness of the 3D Monitor System for Medical Education During Neurosurgical Operation

BACKGROUND

Three-dimensional (3D) graphics are used in the medical field, especially during surgery. Although 3D monitoring is useful for medical education, its effectiveness needs to be objectively evaluated. The aim of this study was to investigate the efficacy of 3D monitoring in the surgical education of medical students.

METHODS

A questionnaire on high-definition 3D monitoring was given to fifth-year medical students in a 6-year program. Sixty-four students wore polarized glasses and observed a microsurgical operation through a 3D monitor. The questionnaire contained questions on stereopsis, neurosurgical interest, visual impact, comprehension of surgical anatomy and procedures, optical sharpness, active learning enhancement, and eye exhaustion. These parameters were evaluated on a 5-point scale that spanned negative and positive scores.

RESULTS

The average score of each parameter ranged from 3.13 to 3.78, except for eye exhaustion, which was 0.88. The items for which the students reported positive perceptions (scores of 4 or 5) were stereopsis (67.2% of students), neurosurgical interest (62.5%), visual impact and optical sharpness (60.9% for both), active learning enhancement (57.8%), and comprehension of surgical anatomy (50.0%) and procedures (42.2%). By contrast, only eye exhaustion was evaluated negatively (26.6%).

CONCLUSION

The use of 3D monitoring systems in medical education offers the advantage of stereopsis and contributes to surgical training. However, improvements are required to decrease eye exhaustion.

Prevalence of and risk factors for enlarged perivascular spaces in adult patients with moyamoya disease

Background

Enlarged perivascular spaces (EPVS) are often observed with magnetic resonance imaging in patients with small vessel disease. However, the risk factors, radiological features, and clinical relevance of EPVS in patients with moyamoya disease are poorly understood. The purpose of this study was to evaluate EPVS, the risk factors of many EPVS, and the pathophysiology of EPVS in adult patients with moyamoya disease.

Methods

One hundred cerebral hemispheres of 50 adult patients with moyamoya disease were examined. The control group consisted of 50 age/sex-matched patients without ischemic disease. The numbers of EPVS at the level of the centrum semiovale per hemisphere were compared between the moyamoya disease and control groups. In each hemisphere, the total numbers of EPVS were categorized into five grades (0–4), and the clinical and radiological characteristics of the predictive factors in patients in the high EPVS grade group (EPVS grade = 4) were assessed.

Results

The EPVS counts and grades were significantly higher in the moyamoya disease group. Analyses of the background characteristics of the patients with moyamoya disease revealed that significantly higher prevalence of high EPVS grades were associated with the female sex, hypertension, high magnetic resonance angiography scores, high numbers of flow voids in the basal ganglia, high brain atrophy scores, ivy signs, and white matter lesions. A logistic multivariate analysis of the patients with high EPVS grades revealed significant associations with the female sex, hypertension, and flow voids in the basal ganglia.

Conclusions

Increased EPVS were confirmed in adult patients with moyamoya disease, and the associated clinical and radiological factors were identified. The presence of hypertension, the female sex, and flow voids in the basal ganglia were important for predicting high EPVS grades in patients with moyamoya disease. Reductions in arterial pulsations with steno-occlusive changes can inhibit the flow of interstitial fluid, which can increase the number of EPVS in patients with moyamoya disease. Other clinical factors, such as the female sex and hypertension, may promote secondary brain damage in patients with moyamoya disease. Further evaluations of EPVS in patients with moyamoya disease are needed to better understand their pathophysiological importance.

Erdheim-Chester Disease Involving the Central Nervous System with the Unique Appearance of a Coated Vertebral Artery

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis. It is characterized by multiple xanthogranulomatous masses throughout the body, predominantly in the tibia. One of the characteristic radiological findings of the lesions associated with ECD is a “coated artery,” which is often observed in the aorta. Although approximately one-fourth of ECD cases involve the central nervous system (CNS), an intracranial-coated artery has only been reported in four cases. We report a case of ECD that involves the CNS and has the unique appearance of a coated vertebral artery (VA). These tumors entirely encase the bilateral VAs without stenosis and are attached to the dura. Cranial magnetic resonance imaging also showed multiple extra-axial tumors in the cavernous sinus, the frontal convexity, and the orbital cavity. Further investigation revealed additional extracranial lesions around the cervical carotid artery, at the bilateral tibia, and at the elbow joint. A biopsy of the cervical and tibial lesions confirmed ECD. Steroid therapy resulted in a month-long improvement of preoperative symptoms. However, the patient’s condition gradually progressed and he died of pneumonia 1 year after ECD diagnosis. The encasement of the intracranial artery by the tumor without stenosis and the dural attachment suggest ECD, which requires whole body investigation.

Electrophysiological influence of temporal occlusion of the parent artery during aneurysm surgery

Intraoperative monitoring of the motor evoked potential (MEP) during cerebral aneurysm surgery has been widely used to confirm surgical safety. In this study, we retrospectively analyzed the influence of the MEP amplitude resulting from temporal occlusion of the parent artery, and appropriate judgement in the surgery was discussed. Ten patients underwent temporal occlusion of the parent artery during aneurysm surgery, and five of these patients showed a decrease in the MEP amplitude following temporal arterial occlusion. Clinical factors in patients with and without MEP decrease were compared. The time gap between the surgical procedure and the MEP change and recovery was then investigated. A decrease in the MEP amplitude caused by temporal occlusion had a significantly higher occurrence compared with permanent clip failure. The time from the release procedure to MEP amplitude recovery was relatively longer than the time from the occlusion procedure to the decrease in MEP amplitude. The time from release procedure to MEP amplitude recovery showed a weak correlation with the parent artery occlusion time. There is a time gap between releasing the temporal arterial occlusion and MEP recovery that is similar to temporal parent arterial occlusion and the MEP decrease. The cause of MEP amplitude should be judged carefully, and influence of parent artery temporal occlusion should be taken into consideration during aneurysm clipping.

Intraoperative Mapping and Monitoring of the Pyramidal Tract Using Endoscopic Depth Electrodes

OBJECTIVE

To evaluate motor function during neuroendoscopic resectioning of deep-seated brain tumors using endoscopically guided depth electrodes.

METHODS

For 12 cases of thalamic tumors, including high-grade gliomas, germinomas, and malignant lymphomas, depth electrodes were inserted using endoscopic guides between the tumor and the pyramidal tract in the thalamus. Motor-evoked potentials (MEPs) were continuously recorded during neuroendoscopic resectioning of the tumors.

RESULTS

Monitoring of MEP responses using depth electrodes in all 12 cases was successful. The minimum stimulus intensity threshold required to induce MEP responses was 3 mA. Gross total or subtotal resections were successful with this technique for all patients with glioma. No additional neurologic impairments were found after surgery in any of the cases.

CONCLUSIONS

Continuous MEP measurement using depth electrodes can serve as a new monitoring technique for endoscopic resectioning of deep-seated brain tumors.

Complementary Relation Between Direct and Indirect Bypass in Progress of Collateral Circulation in Moyamoya Disease

BACKGROUND

One of the important aims of surgery for moyamoya disease is to establish indirect revascularization. The purpose of this study was to assess the progress of the middle meningeal artery (MMA) after our novel preservation method and to evaluate the relation between direct and indirect bypass in the chronic stage.

METHODS

A total of 24 hemispheric sides of 19 patients with moyamoya disease were included in this study. Craniotomy was performed with preservation of the MMA during the procedure, then direct bypass was carried out. The relationship between anatomic variations of the MMA and success rate of preserving the MMA during craniotomy was noted. The alteration of the MMA and superficial temporal artery (STA) diameters was then evaluated using magnetic resonance imaging, and the correlation between the MMA and the STA in the chronic stage was examined.

RESULTS

In total, the MMA was preserved during craniotomy in 20 hemispheric sides (83.3%). During the 3-year follow-up period, the MMA and STA diameters were significantly increased. At 3 years after surgery, the alteration of the MMA diameter was significantly more marked in pediatric cases than in adult cases, and MMA diameter was moderately but significantly negatively correlated with STA diameter.

CONCLUSIONS

In moyamoya disease, the MMA could be developed as a pathway for indirect revascularization even after simple preservation, especially in pediatric patients. The progress of the MMA and the STA occurs through their synergistic interaction, and the balance might be decided based on their complementary relations in the chronic stage.

Pathophysiological consideration of medullary streaks on FLAIR imaging in pediatric moyamoya disease

OBJECTIVE Medullary streaks detected on fluid-attenuated inversion recovery (FLAIR) imaging have been considered to be reflected ischemic regions in pediatric moyamoya disease. The purpose of this study was to evaluate these medullary streaks both clinically and radiologically and to discuss associated pathophysiological concerns. METHODS The authors retrospectively reviewed data from 14 consecutive pediatric patients with moyamoya disease treated between April 2009 and June 2016. Clinical and radiological features and postoperative imaging changes were analyzed. In 4 patients, hyperintense medullary streaks on FLAIR imaging (HMSF) at the level of the centrum semiovale were detected. RESULTS The HMSF were coincident with hyperintense medullary streaks on a T2-weighted image, though they were not completely coincident with the vasculature on either a T2*-weighted image or contrast-enhanced CT. Analysis revealed significantly higher values in terms of MR angiography scores, number of flow voids of the basal ganglia, and the presence of the medullary artery in the group with HMSF than in those without. In contrast, the presence of white matter damage was significantly less frequent in the HMSF group. All HMSF disappeared after surgery, and the mean apparent diffusion coefficient at the same level was significantly reduced postoperatively. CONCLUSIONS Although HMSF should be associated with collateral circulation in moyamoya disease, other factors may be involved, including stagnated cerebrospinal fluid or vasogenic edema that is relevant to the impaired state of the white matter. Findings in this study provide insight into the pathophysiological basis of the perivascular space in moyamoya disease.

Note: Development of a new Bridgman-type high pressure cell for accurate dielectric measurements

We developed a new high pressure cell which allows us to perform accurate dielectric measurements above 3 GPa. The developed cell is based on Bridgman type opposed anvil cells with electrodes immersed into holes in the anvils in order to make the electrode area constant under compression. As a feasibility experiment, dielectric measurements for H₂O were conducted up to 6.6 GPa and obtained dielectric constants are well consistent with previous studies.