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.

A Case of Perimesencephalic Subarachnoid Hemorrhage with Cerebral Venous Sinus Thrombosis due to Stenosis of the Junction of the Vein of Galen and Rectus Sinus.

Perimesencephalic subarachnoid hemorrhage (PMSAH) is a group of diseases characterized by bleeding around the brainstem. In recent years, it has been suggested that PMSAH is associated with the venous system. We report a case of PMSAH caused by stenosis of the junction of the vein of Galen (VG) and the rectus sinus (RS). A 39-year-old man presented with restlessness at work. He was administered diazepam, and a few minutes later, his consciousness became clear. Imaging showed subarachnoid hemorrhage (SAH) around the right midbrain, occlusion of the right sigmoid sinus and the right transverse sinus, stenosis of the junction of the VG and RS, T2 hyperintensity in the right middle temporal gyrus, and obstruction of the right vein of Labbe. The location of the SAH coincided with stenosis of the junction of the VG and RS. PMSAH was diagnosed due to the increase in intracranial venous pressure caused by the patient's sinus obstruction in addition to the stenosis of the junction of the VG and RS. It is necessary to pay attention to venous return when PMSAH is observed.

Preoperatively estimated graft flow rate contributes to the improvement of hemodynamics in revascularization for Moyamoya disease.

OBJECTIVES: Superficial temporal artery (STA)-middle cerebral artery (MCA) bypass operation is an effective treatment for patients with Moyamoya disease, and the hemodynamic parameters are reported to be improved after operation. However, there is no report concerning hemodynamic changes from the viewpoint of the preoperative anatomical structure of grafts. In this study, we evaluated the correlation between the preoperatively estimated blood flow of the graft obtained through image-based computational fluid dynamics (CFD) analysis and the hemodynamic changes in the acute phase after revascularization. MATERIALS AND METHODS: A total of 30 hemispheric sides of 23 patients were examined. The blood flow, that is, flow rate (FR) of the STA branches that were anastomosed to the MCA was evaluated using CFD analysis based on computed tomography (CT) angiography imaging data. The correlations between the FR and the hemodynamic changes in the acute phase after revascularization obtained through CT perfusion were assessed. RESULTS: The preoperatively estimated FR of the graft was moderately correlated with the changes in the mean transit time significantly and weakly correlated with those in the cerebral blood flow and cerebral blood volume. In addition, the FR was strongly correlated with age and the diameter of the STA from the origin to the bifurcation. CONCLUSION: The preoperatively estimated FR of the graft obtained through image-based CFD analysis contributed to the improvement of the mean transit time after revascularization. Because the FR of the graft was associated with the diameter of the STA, the size of the STA might be an important factor in postoperative hemodynamic changes. This might lead to the risk assessment of acute drastic hemodynamic changes as cerebral hyperperfusion, and consequently, better surgical outcomes might be expected.

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.

Association of a Subperiosteal Hematoma With Minor Injury.

An intraorbitalsubperiosteal hematoma is a rare clinical entity that is usually caused by head trauma. The authors experienced a patient involving an intraorbital hemorrhage that was associated with minor injury in the forehead and that required surgical decompression. The authors describe this rare case involving an intraorbitalsubperiosteal hematoma that occurred in a conscious young boy who had no remarkable head injury and who had sudden onset of proptosis. Three-dimensional computed tomography, which was conducted with a volume-rendering method, was very useful, and the transorbital approach that was used to remove the hematoma was very effective. The patient showed good recovery. The pathogenesis of the intraorbitalsubperiosteal hemorrhage could not be fully explained, and, thus, the authors suggest that a possible pathogenesis involved the migration of the hemorrhage from the forehead into the intraorbital region.

[Cerebral ischemia originating from rotational vertebral artery occlusion caused by C5/6 spondylotic changes: a case report].

A 68-year-old man presented with sudden onset of left hemiparesis, diplopia and numbness of the left side of the body and was admitted to our hospital. MRI of the brain revealed no abnormality. However, neurological examination on admission strongly suggested ischemia of the brainstem. Under anticoagulation therapy his symptoms gradually disappeared by the fourth hospital day. He had a past history of bouts of unconsciousness caused by right rotation of the head. Dynamic plain roentgenograms of the cervical spine showed spondylotic changes and lateral osteophyte formation at C5/6 without instability. Computed tomography (CT)-angiography demonstrated narrowing of the right vertebral artery due to compression of the lateral osteophyte at C5/6. Vertebral angiography revealed complete occlusion of the right vertebral artery induced by right rotation of the head. The artery-to-artery embolism caused by repeated occlusion of the right vertebral artery due to the neck motion was suggested as the mechanism of ischemic attack in this patient. Osteophytectomy at C5/6 via the anterior approach successfully treated dynamic occlusion of the right vertebral artery. Occlusion of the vertebral artery at C1/2 by the head rotation is well known as Bow-Hunter's syndrome. However, dynamic occlusion due to spondylotic changes at C5/6 is rare. In case of ischemic attack of the posterior circulation with lateral osteophyte formation of the cervical spine, dynamic occlusion mechanisms of the vertebral artery at the lower cervical level should be considered.

Neural differentiation potential of peripheral blood- and bone-marrow-derived precursor cells.

Transplantation of mesenchymal stem cells (MSCs) prepared from adult bone marrow (BMSCs) has been reported to ameliorate functional deficits in several CNS diseases in experimental animal models. Bone marrow was enriched in MSCs by selecting for plastic-adherent cells that were grown to confluency in appropriate culture conditions as flattened fibroblast-like cells. Despite the fact that the stem/precursor cells in peripheral blood are widely used for reconstruction in the hematopoietic system, it is not fully understood whether peripheral blood-derived plastic-adherent precursor/stem cells (PMSCs) can differentiate into a neural lineage. To compare the potential of PMSCs and BMSCs for neural differentiation in vitro, BMSCs and PMSCs were prepared from the adult rat and expanded in culture. Although the growth rate of PMSCs was less than BMSCs, immunocytochemical and RT-PCR analyses indicated that both MSC types were successfully induced to nestin-positive neurospheres in the presence of EGF and bFGF. After withdrawal of the mitogens, these cells could differentiate into neurofilament-positive neurons or GFAP-positive glia. Thus, our findings suggest the potential use of PMSCs for a cell therapy in CNS diseases.