Ryota Kurogi

Gene Expression Profiling and Bioinformatic Analysis of Rabbit Basilar Artery after Experimental Subarachnoid Hemorrhage

Objective: The molecular mechanisms which contribute to the development of vascular events including cerebral vasospasm after subarachnoid hemorrhage (SAH) in cerebral artery remain to be elucidated. In this study, we investigated the time course of changes in the gene expression of cerebral artery using rabbit SAH model and performed bioinformatic analysis of differentially expressed genes. Methods: Rabbit basilar arteries were harvested on days 3, 5, and 7 after initial hemorrhage. Changes in gene expression of the rabbit basilar artery were investigated by using Agilent rabbit oligo microarrays and analyzed the data by Ingenuity Pathway Analysis (IPA). Results: Among investigated 43,623 genes, 1,121 genes were differentially expressed at least 1 time point. We found that the number, magnitude of fold change, and gene expression pattern were most dynamically changed on day 3, whereas narrowing of the basilar artery became most severe on day 5. In microarray datasets analyzed by IPA revealed that 25 biological functions identified from differentially expressed genes were significantly upregulated. Conclusion: Our findings that were based on gene expression analysis followed by bioinformatic analysis may provide a simple basis to interlink the various presumed pathogenesis of vascular events including cerebral vasospasm after SAH.

Midline and off-midline infratentorial supracerebellar approaches to the pineal gland

OBJECTIVE A common approach to lesions of the pineal region is along the midline below the torcula. However, reports of how shifting the approach off midline affects the surgical exposure and relationships between the tributaries of the vein of Galen are limited. The purpose of this study is to examine the microsurgical and endoscopic anatomy of the pineal region as seen through the supracerebellar infratentorial approaches, including midline, paramedian, lateral, and far-lateral routes. METHODS The quadrigeminal cisterns of 8 formalin-fixed adult cadaveric heads were dissected and examined with the aid of a surgical microscope and straight endoscope. Twenty CT angiograms were examined to measure the depth of the pineal gland, slope of the tentorial surface of the cerebellum, and angle of approach to the pineal gland in each approach. RESULTS The midline supracerebellar route is the shortest and provides direct exposure of the pineal gland, although the culmen and inferior and superior vermian tributaries of the vein of Galen frequently block this exposure. The off-midline routes provide a surgical exposure that, although slightly deeper, may reduce the need for venous sacrifice at both the level of the veins from the superior cerebellar surface entering the tentorial sinuses and at the level of the tributaries of the vein of Galen in the quadrigeminal cistern, and require less cerebellar retraction. Shifting from midline to off-midline exposure also provides a better view of the cerebellomesencephalic fissure, collicular plate, and trochlear nerve than the midline approaches. Endoscopic assistance may aid exposure of the pineal gland while preserving the bridging veins. CONCLUSIONS Understanding the characteristics of different infratentorial routes to the pineal gland will aid in gaining a better view of the pineal gland and cerebellomesencephalic fissure and may reduce the need for venous sacrifice at the level of the tentorial sinuses draining the upper cerebellar surface and the tributaries of the vein of Galen.

Prehospital antiplatelet use and functional status on admission of patients with non-haemorrhagic moyamoya disease: a nationwide retrospective cohort study (J-ASPECT study).

Objectives To elucidate the association between antiplatelet use in patients with non-haemorrhagic moyamoya disease before hospital admission and good functional status on admission in Japan. Design Retrospective, multicentre, non-randomised, observational study. Setting Nationwide registry data in Japan. Participants A total of 1925 patients with non-haemorrhagic moyamoya disease admitted between 1 April 2012 and 31 March 2014 in Japan. Main outcome measure We performed propensity score-matched analysis to examine the association between prehospital antiplatelet use and no significant disability on hospital admission, as defined by a modified Rankin Scale score of 0 or 1. Results Propensity-matched patients who received prehospital antiplatelet drugs were associated with a good outcome on hospital admission (OR adjusted for all covariates, 3.82; 95% CI 1.22 to 11.99) compared with those who did not receive antiplatelet drugs prior to hospital admission. Conclusions Prehospital antiplatelet use was significantly associated with good functional status on hospital admission among patients with non-haemorrhagic moyamoya disease in Japan. Our results suggest that prehospital antiplatelet use should be considered when evaluating outcomes of patients with non-haemorrhagic moyamoya disease.

Comparing intracerebral hemorrhages associated with direct oral anticoagulants or warfarin

Objectives This cross-sectional survey explored the characteristics and outcomes of direct oral anticoagulant (DOAC)–associated nontraumatic intracerebral hemorrhages (ICHs) by analyzing a large nationwide Japanese discharge database. Methods We analyzed data from 2,245 patients who experienced ICHs while taking anticoagulants (DOAC: 227; warfarin: 2,018) and were urgently hospitalized at 621 institutions in Japan between April 2010 and March 2015. We compared the DOAC- and warfarin-treated patients based on their backgrounds, ICH severities, antiplatelet therapies at admission, hematoma removal surgeries, reversal agents, mortality rates, and modified Rankin Scale scores at discharge. Results DOAC-associated ICHs were less likely to cause moderately or severely impaired consciousness (DOAC-associated ICHs: 31.3%; warfarin-associated ICHs: 39.4%; p = 0.002) or require surgical removal (DOAC-associated ICHs: 5.3%; warfarin-associated ICHs: 9.9%; p = 0.024) in the univariate analysis. Propensity score analysis revealed that patients with DOAC-associated ICHs also exhibited lower mortality rates within 1 day (odds ratio [OR] 4.96, p = 0.005), within 7 days (OR 2.29, p = 0.037), and during hospitalization (OR 1.96, p = 0.039). Conclusions This nationwide study revealed that DOAC-treated patients had less severe ICHs and lower mortality rates than did warfarin-treated patients, probably due to milder hemorrhages at admission and lower hematoma expansion frequencies.

Upregulation of tissue inhibitor of metalloproteinase-1 contributes to restoration of the extracellular matrix in the rabbit basilar artery during cerebral vasospasm after subarachnoid hemorrhage

Vascular remodeling caused by extracellular matrix (ECM) metabolism contributes to the development of cerebral vasospasm after subarachnoid hemorrhage (SAH). The balance between tissue inhibitor of metalloproteinases (TIMPs) and matrix metalloproteinases (MMPs) plays an important role in ECM remodeling. We investigated the mechanism of vascular remodeling following cerebral vasospasm in a rabbit double hemorrhage model. Rabbit basilar arteries were harvested on days 3, 5, and 7 after initial hemorrhage. TIMP-1, TIMP-2, MMP-2, and MMP-9 mRNA and protein expression were investigated with microarray analysis, quantitative real-time PCR, immunoblot analysis, and enzyme-linked immunosorbent assay (ELISA). The expression and localization of TIMP-1, TIMP-2, MMP-2, MMP-9, elastin, fibronectin, laminin, and collagens I, III, and IV were investigated with immuohistochemical staining. After SAH, TIMP-1 mRNA and protein expression were significantly increased on day 3 and then decreased to the control level on days 5 and 7. MMP-9 protein expression was significantly increased on day 7. TIMP-2 and MMP-2 mRNA and protein expression were significantly increased on day 7. Elastin, fibronectin, laminin, and collagens I, III, and IV protein expression was decreased on day 3 and then restored to control levels on day 7. Upregulation of TIMP-1 during the early phase of cerebral vasospasm may contribute to the recovery of the ECM during the late phase of cerebral vasospasm, resulting in a protective role of TIMP-1 from cerebral vasospasm. Moreover, the increase in arterial compliance by the decrease in ECM during the early phase of cerebral vasospasm may facilitate vasoconstriction of the cerebral artery.

Altered Expression of MicroRNA-15a and Kruppel-Like Factor 4 in Cerebrospinal Fluid and Plasma After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND Cerebral vasospasm (CVS) is a major determinant of prognosis in patients with subarachnoid hemorrhage (SAH). Alteration in the vascular phenotype contributes to development of CVS. However, little is known about the role of microRNAs (miRNAs) in the phenotypic alteration after SAH. We investigated the expression profile of miRNAs and the chronologic changes in the expression of microRNA-15a (miR-15a) and Kruppel-like factor 4 (KLF4), a potent regulator of vascular phenotype modulation that modulates the expression of miR-15a, in the plasma and cerebrospinal fluid (CSF) of patients with SAH. METHODS Peripheral blood and CSF samples were collected from 8 patients with aneurysmal SAH treated with endovascular obliteration. Samples obtained from 3 patients without SAH were used as controls in the analysis. Exosomal miRNAs were isolated and subjected to microarray analysis with the three-dimensional-gene miRNA microarray kit. The time course of the expression of miR-15a and KLF4 was analyzed using quantitative real-time polymerase chain reaction. RESULTS Microarray analysis showed that 12 miRNAs including miR-15a were upregulated or downregulated both in the CSF and in plasma after SAH within 3 days. Quantitative real-time polymerase chain reaction showed that miR-15a expression was significantly increased in both the CSF and plasma, with a peak around 3-5 days after SAH, whereas the expression of KLF4 was significantly decreased around 1-3 days after SAH and remained lower than in controls. CONCLUSIONS Our results suggest that an early and persistent decrease in KLF4 followed by an increase in miR-15a may contribute to the altered vascular phenotype, resulting in development of CVS.

Upregulation of relaxin after experimental subarachnoid hemorrhage in rabbits.

Background. Although relaxin causes vasodilatation in systemic arteries, little is known about its role in cerebral arteries. We investigated the expression and role of relaxin in basilar arteries after subarachnoid hemorrhage (SAH) in rabbits. Methods. Microarray analysis with rabbit basilar artery RNA was performed. Messenger RNA expression of relaxin-1 and relaxin/insulin-like family peptide receptor 1 (RXFP1) was investigated with quantitative RT-PCR. RXFP1 expression in the basilar artery was investigated with immunohistochemistry. Relaxin concentrations in cerebrospinal fluid (CSF) and serum were investigated with an enzyme-linked immunosorbent assay. Using human brain vascular smooth muscle cells (HBVSMC) preincubated with relaxin, myosin light chain phosphorylation (MLC) was investigated with immunoblotting after endothelin-1 stimulation. Results. After SAH, RXFP1 mRNA and protein were significantly downregulated on day 3, whereas relaxin-1 mRNA was significantly upregulated on day 7. The relaxin concentration in CSF was significantly elevated on days 5 and 7. Pretreatment with relaxin reduced sustained MLC phosphorylation induced by endothelin-1 in HBVSMC. Conclusion. Upregulation of relaxin and downregulation of RXFP1 after SAH may participate in development of cerebral vasospasm. Downregulation of RXFP1 may induce a functional decrease in relaxin activity during vasospasm. Understanding the role of relaxin may provide further insight into the mechanisms of cerebral vasospasm.

Relationship Between the Horizontal Part of the Sigmoid Sinus and the Line Through the Digastric Point and Posterior Edge of the Condyle: An Anatomic and Radiologic Study

OBJECTIVE This study aims to determine whether the line between the digastric point and posterior edge of the occipital condyle (DC line) could be a new surface landmark for the posterior margin of the horizontal part of the sigmoid sinus. METHODS Cadaveric specimens were used to show the relationship between the DC line and retrosigmoid craniotomy. Three-dimensional computed tomography angiography images of adult heads (56 sides) were analyzed to measure the distance between the DC line and the horizontal part of the sigmoid sinus at the digastric point, posterior edge of the condyle, and midpoint of the line. RESULTS The DC line was roughly parallel and posterior to the posterior margin of the sigmoid sinus. The distance between the DC line and the posterior edge of the sigmoid sinus at the digastric point, condyle, and midpoint of the line measured 4.7 ± 3.3 mm, 5.9 ± 2.6 mm, and 1.3 ± 2.2 mm, respectively. All sigmoid sinuses coursed anterior to the digastric point and condyle but in 17.9% (10/56 sides) the posterior edge of the sigmoid sinus extended a maximum of 4.1 mm posterior to the midpoint of the DC line. CONCLUSIONS The DC line can be used as a new surface landmark for estimating the position of the horizontal part of the sigmoid sinus. The posterior edge of the sinus may extend posterior to the line at the midpoint; thus, care should be taken to prevent sinus injury when drilling around the midpoint of the line.

Surgical Anatomy of the Eustachian Tube for Endoscopic Transnasal Skull Base Surgery: A Cadaveric and Radiologic Study

OBJECTIVE The endoscopic endonasal approach to the anatomically complex lateral skull base presents technical challenges. The use of the eustachian tube as a landmark to identify the petrous internal carotid artery has recently been reported, and this study aims to define the anatomic relationship between the eustachian tube and its surrounding structures using cadaveric dissection and radiologic analysis. METHODS To clarify the relationship of the eustachian tube with its surrounding structures, we performed endoscopic and microscopic dissection of 4 adult cadaveric heads and analyzed computed topography scans from 20 patients. RESULTS The eustachian tube is divided into the osseous and cartilaginous parts. The cartilaginous part can be further subdivided into the posterolateral, middle, and anteromedial parts, based on its relationship to the skull base. The eustachian tube is closely related to the pterygoid process of the sphenoid bone, the foramen lacerum, and the petrosal apex and is directed away from the oblique sagittal plane almost parallel to the vidian canal at 12.2° ± 6.2° (mean ± standard deviation). The relationship between the course of the vidian canal and the eustachian tube can aid the estimation of the anatomic course of the horizontal segment of the petrous carotid artery. CONCLUSIONS The eustachian tube is a useful landmark for predicting the course of the internal carotid artery when accessing the lateral skull base regions via an endonasal route. A profound understanding of the relationship between the eustachian tube and the surrounding skull base structures is important for endoscopic endonasal skull base surgeries.

Microsurgical Anatomy of the Jugular Process as an Anatomical Landmark to Access the Jugular Foramen: A Cadaveric and Radiological Study

BACKGROUND The jugular process forms the posteroinferior surface of the jugular foramen and is an important structure for surgical approaches to the foramen. However, its morphological features have not been well described in modern texts. OBJECTIVE To elucidate the microsurgical anatomy of the jugular process and examine its morphological features. METHODS Five adult cadaveric specimens were dissected in a cadaveric study, and computed tomography data from 31 heads (62 sides) were examined using OsiriX (Pixmeo SARL, Bernex, Switzerland) to elucidate the morphological features of the jugular process. RESULTS The cadaveric study showed that it has a close relationship with the sigmoid sinus, jugular bulb, rectus capitis lateralis, lateral atlanto-occipital ligament, and lateral and posterior condylar veins. The radiographic study showed that 9/62 sigmoid sinuses protruded inferiorly into the jugular process and that in 5/62 sides, this process was pneumatized. At the entry of the jugular foramen, if the temporal bone has a bulb-type jugular bulb, and if surgery concerns the right side of the head, the superior surface of the jugular process is more likely to be steep. CONCLUSION The jugular process forms the posteroinferior border of the jugular foramen. Resection of the jugular process is a critical step for opening the jugular foramen from the posterior and lateral aspects. Understanding the morphological features of the jugular process, and preoperative and radiographical examination of this process thus help skull base surgeons to access the jugular foramen.