Noriaki Matsubara

Tenascin-C is induced in cerebral vasospasm after subarachnoid hemorrhage in rats and humans: a pilot study

Abstract Objective: Cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) has been hypothesized to occur because of both inflammation-mediated sustained contraction of smooth muscle cells and vascular remodeling. As our recent study showed that tenascin-C (TN-C), an extracellular matrix glycoprotein which is up-regulated in inflammatory states and is associated with tissue remodeling, causes vasospasm-like changes in arterial walls, we examined whether TN-C might be induced in relation to the occurrence of cerebral vasospasm experimentally and clinically. Methods: First, rat models were produced by means of a single cisternal injection of either autologous arterial blood or saline. Immunostaining for TN-C was performed with basilar arteries obtained from non-operated rats (n = 3) and on days 1-4 in SAH (n = 18) or saline-injected (n = 12) rats. Second, levels of TN-C were prospectively measured in serum in 31 consecutive patients diagnosed with aneurysmal SAH on days 1-12 and compared between those with and without subsequent cerebral vasospasm. Results: In SAH rats, marked induction of TN-C immunoreactivity was shown throughout the vasospastic arterial wall, especially in the smooth muscle cell layers, in comparison with control rats. In a clinical study, serum TN-C levels increased transiently, the extent being significantly greater in patients with subsequent vasospasm; the peak occurred 2·4 days before an increase in the mean transcranial Doppler velocity to 120 cm/s and 3·6 days before the onset of symptomatic vasospasm (n = 14). Discussion: This is the first study suggesting TN-C increases with close linkage to the occurrence of vasospasm after SAH.

Mechanism of the formation of dural arteriovenous fistula: the role of the emissary vein.

Dural arteriovenous fistula (DAVF) can be separated into two types: DAVF which drains through an affected sinus (sinus type) and DAVF with direct reflux to the cortical vein (non-sinus type). The present report attempted to clarify the mechanism of formation and development of DAVF focusing on the emissary vein (EV) hypothesis. First, inflammation occurs at the penetrating point of the EV on the dura due to idiopathic or secondary causes. Local inflammatory reactions induce vessel dilatation and neovascularization, and subsequently create arteriovenous (AV) connections on the arteriole level. Although EV communicating with dural arteries might play a role as draining routes at first, they start to degrade due to compression of enlarged emissary arteries or to a hemodynamic shift to the drainage pathway of least resistance. Following the occlusion of drainage pathway through EV into the sinus or cortical veins may form, resulting in clinically detectable DAVF. The AV shunt then expands to the surrounding dura associated with recruitment of feeders from distant sites induced by expression of angiogenetic factors and a shift in the hemodynamic balance. In sinus type DAVF, the sinus is progressively compartmentalized and finally occludes due to thrombogenesis with activated coagulopathy or to hemodynamic hypertrophy of the sinus wall. This progression results in the mature, aggressive DAVF with drainage impairments. Previous mechanistic hypotheses focusing on sinus hypertension and sinus thromboses cannot explain the pathogenesis of non-sinus type of DAVF. Although the etiology of DAVF may be concerned by the thrombo-occlusive change of sinus, the unique theory presented in this report may enable an understanding of the common etiology of both types of DAVF.

Magnetic resonance fluid dynamics for intracranial aneurysms—comparison with computed fluid dynamics

BackgroundHemodynamics in intracranial aneurysms is thought to play an important role in their growth and rupture. Usual computed fluid dynamics (CFD) based on three-dimensional (3D) computed tomographic (CT) angiography requires a time-consuming process for analysis. Magnetic resonance fluid dynamics (MRFD) based on MR images is a new tool for analyzing flow dynamics and a promising method for obtaining such information more easily. We compared the data from MRFD and CFD and studied the clinical feasibility of MRFD.MethodsA total of 15 aneurysms, including two ruptured ones, in 15 patients were investigated with MR imaging and 3D-CT angiography. The flow data of MRFD and CFD, 3D stream lines, flow velocity profile and wall shear stress (WSS) were extracted from the image reconstruction and were compared each other.ResultsBoth flow dynamics images showed quite similar 3D flow pattern and WSS map. However, the calculated value of maximum WSS was quite different and there was no significant correlation. Further, in one ruptured case, CFD showed less visualization to evaluate the intra-aneurysmal flow. Interestingly, one delayed rupture case showed a particular flow pattern with abnormal secondary flow in the bottom of the aneurysm before rupture, which might suggest the specific finding of rupture risk.ConclusionMRFD is a valuable and less invasive tool to evaluate aneurysmal fluid dynamics. It can be obtained from the usual MRI examination without contrast medium and exposure to radiation. Although there is a problem of consistency of the absolute value of WSS between MRFD and conventional CFD, it may be useful to predict the risk of enlargement or rupture of aneurysms based on the information of the similar distribution of WSS and flow patterns. The quantifiable analysis and establishment of a meaningful threshold for high risk should be further studied.

Fenestration of a supraclinoid internal carotid artery associated with dual aneurysms: case report.

BACKGROUND AND IMPORTANCE:We present a rare case of fenestration of the left supraclinoid intracranial internal carotid artery with 2 associated aneurysms arising proximally and distally from the fenestration that were successfully treated with endovascular coil embolization. This is the first report of these types of aneurysms treated with coiling alone. CLINICAL PRESENTATION:A 47-year-old woman underwent a diagnostic workup; magnetic resonance angiography incidentally revealed 2 tandem aneurysms at the supraclinoid and paraclinoid portion of the left internal carotid artery. Angiography revealed fenestration of the left supraclinoid internal carotid artery with 2 aneurysms both proximal and distal to the fenestration. The patient underwent endovascular coil embolization of the aneurysms simultaneously. The smaller trunk was intentionally occluded to achieve complete packing of the proximal aneurysm. Both aneurysms were totally occluded, and no neurological deficits developed in the patient. CONCLUSION:Based on previous reports, fenestration has the potential to form an aneurysm, and there seemed to be a relatively high incidence of rupture if accompanied by aneurysm. Coiling is one good option to treat aneurysms and should be considered when multiple aneurysms exist because all aneurysms can be treated simultaneously. Proximal occlusion of the smaller trunk is acceptable because of a retrograde flow from the distal end, even if one exists.

The mechanism of catheter kickback in the final stage of coil embolization for aneurysms: the straightening phenomenon.

The catheter kickback phenomenon often occurs in the last stage of coil packing for cerebral aneurysms. This behavior is considered the result of either a lack of space in the sac or a stiff detaching zone. In order to clarify its mechanism, focused stretch-resistance (SR) coil simulation models were tested. Various commercially available SR coils were inserted into a cylinder or an aneurismal sac made from a silicone tube with a smaller than prescribed diameter. A magnified SR coil model (straight type) of fishing line was created for simulation. Numerical analysis for the changes in coil behavior were verified. All SR coils showed hardening and straightening at the last few millimeters, resulting in catheter kickback. In a magnified coil experiment, straightening was also realized when folding into a narrow cylinder. The SR line coursed in the canal of the first loops and shifted to the outside in the middle portion. Gaps among first coil pitches were enlarged on after insertion into the narrower space. Shortage of the SR line was calculated to reach a maximum of 32%. The straightening phenomenon is due to SR line shortening and subsequent condensation of pitches of the first loops at the coil end. Coil tail flexibility was lost, and the coil behaved as a stiff wire. Straightening is an important factor in the kickback phenomenon. Shorter final SR coils should be selected, and coil designs should be improved.

A novel pressure sensor with an optical system for coil embolization of intracranial aneurysms. Laboratory investigation.

OBJECT In endovascular coil embolization for an intracranial aneurysm, the excessive pressure created during coil insertion into an aneurysm can cause a catastrophic rupture or dislodge a microcatheter tip from the aneurysm dome, resulting in insufficient embolization. Such undue mechanical pressure can only be subjectively detected by the subtle tactile feedback the surgeon experiences. Therefore, the authors of this study developed a new sensor device to measure the coil insertion pressure via an optical system. METHODS This novel sensor system consists of a hemostatic valve connected to the proximal end of a microcatheter (Y-connector). The sensor principle is based on an optical system composed of a light-emitting diode (LED) and a line sensor. The latter measures how much the coil-delivery wire slightly bends in response to the insertion pressure by detecting the wire shadow. This information is translated into a given force level. Experimental aneurysm embolization was performed using this optical sensor. A silicone aneurysm model and an in vivo model (porcine aneurysm model) were used in this study. Several surgeons manually performed the coil insertions. The sensor continuously monitored the mechanical force during the insertions. RESULTS The sensor adequately recorded the coil insertion pressure during embolization. The presence of the sensor did not hinder the embolization procedure in any way. During embolization in the silicone aneurysm model, a sinusoid pattern of pressure occurred, reflecting actual clinical experience. Similar results were obtained in the in vivo study. CONCLUSIONS This new sensor device adequately measures coil insertion pressure. This system provides potentially safer and more reliable aneurysm embolizations.

Usefulness of three-dimensional digital subtraction angiography in endovascular treatment of a spinal dural arteriovenous fistula Report of 2 cases

The use of 3D digital subtraction (DS) angiography provides a better understanding of spinal vascular lesion architecture. The authors report on 2 cases involving a spinal dural arteriovenous fistula (DAVF) and demonstrate the usefulness of 3D DS angiography for endovascular treatment of these spinal DAVFs. In both cases, middle-aged male patients suffered from bilateral leg hypesthesia, gait disturbance, and urinary dysfunction several months before treatment. Spinal angiography revealed DAVFs that were fed by a radicular artery branching from the intercostal artery and draining veins proceeding superiorly along the perimedullary veins. Endovascular embolization was performed in both cases. Selective 3D DS angiography of the intercostal artery clearly demonstrated the tortuous course of the feeder and the relationship among the feeding artery, fistula point, and draining veins in each case. This information was very useful in selecting a working angle for manipulating the microcatheter and for glue injection. In addition, the maximum intensity projection image from rotational DS angiography data clearly showed the fistula point at the dural sleeve and feeder entering the spinal canal via the intervertebral foramen and the relationship with the bone structure. Successful obliteration of the fistulae was achieved in both cases. Selective spinal 3D DS angiography was very useful in understanding the complex spinal vascular architecture and in choosing the best working angle and therapeutic strategy for endovascular treatment of spinal DAVFs.

Evaluation of the characteristics of various types of coils for the embolization of intracranial aneurysms with an optical pressure sensor system

IntroductionIn coil embolization for an intracranial aneurysm, it is important to appropriately choose the coil most suitable for coping with various unforeseen situations. Additionally, because dense coil packing of the aneurysm sac is the most important factor to avoid a recurrence, properly selecting the coil is essential. In this article, the authors measured the coil insertion pressure of various types of coils with a newly developed sensor system, and coil characteristics were investigated.MethodsThe sensor consists of a hemostatic valve connected to the proximal end of a microcatheter. The sensor principle is based on an optical system. Using this, an experimental silicone aneurysm embolization was performed automatically at constant speed. The pattern of the insertion pressure and the maximum insertion pressure (MIP) were analyzed for the various types of coils. The sensor continuously monitored the mechanical force during the insertions.ResultsThe sensor adequately recorded the coil insertion pressure during embolization in each coil. MIP was generally ranked in order of the coil type. The soft type coils required relatively less insertion pressure than standard/helical and 3D type. As for the patterns of coil insertion pressure, each coil presented a saw-like pressure pattern, though we observed some slight differences. 3D type coils showed peak pressure at the moment of “painting”. Coil loop diameters barely affected MIP. However, as to the patterns of pressure, larger size coils more often presented the peak.ConclusionsCoil characteristics were well evaluated. The results obtained here reflected some actual clinical experience. Furthermore, collecting the in vivo study is mandatory, which may provide clinically useful data.

Relationship between low response to clopidogrel and periprocedural ischemic events with coil embolization for intracranial aneurysms

Objectives Low response to antiplatelet drugs is one of the risk factors for ischemic events. We examined the influence of low response to clopidogrel on symptomatic ischemic events and new ischemic MRI lesions with endovascular intracranial aneurysmal coil embolization. Materials and methods Between August 2010 and July 2013, 189 procedures in 181 consecutive patients who underwent endovascular coiling and received clopidogrel before treatment were investigated retrospectively. Platelet aggregation activity was examined by VerifyNow analysis. Low response to clopidogrel was defined as P2Y12 reaction units ≥230 in this study. Symptomatic ischemic complications within 30 days and postoperative new ischemic lesions on MRI–diffusion weighted imaging were evaluated. Results 66 of 189 (34.9%) cases were low responders to clopidogrel. Ischemic complications occurred in 2 of 66 (3.0%) low responders compared with 6 of 123 (4.9%) responders (p=0.72). A new high intensity spot larger than 5 mm was significantly more frequent in low responders (26 of 66; 39.4%) than in responders (26 of 121; 21.2%; p=0.01). On multivariate analysis, independent risk factors for larger new ischemic lesions were low response to clopidogrel, smokers, posterior location, and aneurysms with a larger neck. Conclusions Low response to clopidogrel had little effect on clinical outcome although it increased asymptomatic large ischemic lesions in this cohort.

Results and Current Trends of Multimodality Treatment for Infectious Intracranial Aneurysms

The authors retrospectively reviewed their cases of infectious intracranial aneurysms and discuss results and trends of current treatment modalities including medical, neurosurgical, and endovascular. Twenty patients (10 males and 10 females; mean age 46 years) with 23 infectious aneurysms were treated by various treatment modalities during a 15-year period. Fifteen cases (75.0%) were caused by infective endocarditis. Eleven aneurysms (47.8%) were ruptured. Two aneurysms (8.7%) presented a mass effect and 7 (30.4%) were unruptured and asymptomatic. The average aneurysm size was 6.5 ± 4.8 mm (range 1–22 mm). The aneurysms were located in proximal cerebral circulation in 7 (30.4%) and distal in 16 (69.6%). Six (26.1%) aneurysms were treated surgically (5: trapping, 1: neck clipping), 10 (43.5%) endovascularly (7: trapping, 2: proximal occlusion, 1: saccular coiling), and the remaining 7 (30.4%) medically. Endovascular treatment was gradually increased with time. Medical and surgical treatments were continuously performed during the study period. Surgery was preferred for the patient with intraparenchymal hematoma or treated by bypass surgery. Three periprocedural minor complications occurred in endovascular treatment. There was one postoperative infarction with permanent deficit developed from surgical treatment. During the follow-up period (mean 28.8 months), none of the aneurysms presented a recurrence or rebleeding. Thirteen patients (65.0%) had favorable clinical outcomes (modified Rankin Scale: 0–2), although four (20.0%) had poor outcomes (modified Rankin Score: 5–6). A multimodal approach for the management of infectious aneurysms achieved satisfactory results. Endovascular intervention is a feasible and efficacious treatment option and surgical intervention is still an indispensable procedure.