Search

Endoscopic third ventriculostomy (ETV) has been accepted for obstructive hydrocephalus (OH). We herein present a case of OH and optic nerve sheath edema (ONSE). Although ETV was successful, ONSE worsened. Discussion is focused on the relationship among intracranial hypertension (IH), ETV, and ONSE. The patient was a 19-year-old woman with complaints of headache and emesis. Papilledema was prominent. Radiological examination showed OH as an aqueductal tumor. Endoscopic tumorectomy and ETV were accomplished. Although headache and emesis disappeared, papilledema persisted. On the 4th day, the patient lost light perception. On magnetic resonance imaging, the third ventricular stroma and aqueduct were patent. Nevertheless, ONSE was prominent. After lumbar drainage, her vision was restored. Finally, ventriculoperitoneal shunting was performed, following which ONSE disappeared. IH is not always accompanied by ONSE. However, once it occurs, it may act separately from IH, and ETV may even exacerbate ONSE due to alteration of cerebrospinal fluid (CSF) flow into the chiasmatic cistern. In the optic nerve sheath, CSF pressure is not easily transmitted across different areas; this should explain the dissociation between ONSE and other symptoms of IH. Furthermore, we suggest that ONSE and acute optic dysfunction should be considered an independent crisis as “hydronervus opticus.”

Tumor emboli due to a sarcoma are usually confirmed by an autopsy or operative findings. A sarcoma embolus in an acute stroke patient is rare. We herein report a 37-year-old man with acute stroke caused by internal carotid artery occlusion who underwent embolectomy. A histopathological analysis of an embolus obtained with a mechanical retriever device was diagnosed as undifferentiated sarcoma. This is the first case of extracardiac sarcoma extraction via mechanical retrieval performed during intervention for acute ischemic stroke. A histopathologic evaluation with embolectomy is important for diagnosing tumor emboli.

Background There are several complications associated with Stent-assisted Coil Embolization (SACE) in cerebral aneurysm treatments, due to damaging operations by surgeons and undesirable mechanical properties of stents. Therefore, it is necessary to develop an in vitro simulator that provides both training and research for evaluating the mechanical properties of stents. Methods A new in vitro simulator for three-dimensional digital subtraction angiography was constructed, followed by aneurysm models fabricated with new materials. Next, this platform was used to provide training and to conduct photoelastic stress analysis to evaluate the SACE technique. Results The average interaction stress increasingly varied for the two different stents. Improvements for the Maximum-Likelihood Expectation-Maximization method were developed to reconstruct cross-sections with both thickness and stress information. Conclusions The technique presented can improve a surgeon's skills and quantify the performance of stents to improve mechanical design and classification. This method can contribute to three-dimensional stress and volume variation evaluation and assess a surgeon's skills. Copyright © 2013 John Wiley & Sons, Ltd.

Background: Computer-based simulation is necessary to clarify the hemodynamics in brain aneurysm. Specifically for endovascular treatments, the effects of indwelling intravascular devices on blood stream need to be considered. The most recent technology used for cerebral aneurysm treatment is related to the use of flow diverters to reduce the amount of flow entering the aneurysm. To verify the differences of flow reduction, we analyzed multiple Enterprise stents and two kinds of flow diverters. Materials and Methods: In this research, we virtually modeled three kinds of commercial intracranial stents (Enterprise, Silk, and Pipeline) and mounted to fit into the vessel wall, and deployed across the neck of an IC-ophthalmic artery aneurysm. Also, we compared the differences among multiple Enterprise stents and two flow diverters in a standalone mode. Results: From the numerical results, the values of wall shear stress and pressure are reduced in proportion to the size of mesh, especially in the inflow area. However, the reduced velocity within the aneurysm sac by the multiple stents is not as significant as the flow diverters. Conclusions: This is the first study analyzing the flow alterations among multiple Enterprise stents and flow diverters. The placement of small meshed stents dramatically reduced the aneurysmal fluid movement. However, compared to the flow diverters, we did not observe the reduction of flow velocity within the aneurysm by the multiple stents.

Computer-based simulations are essential for clarifying the hemodynamics of brain aneurysms. Since cerebrovascular disease is often fatal, it is strongly desirable to predict its progression. While previous studies have clarified the initiation mechanism of aneurysms, their growth mechanism remains unclear. Consequently, it is difficult to develop a diagnostic system for predicting aneurysm rupture. This study seeks to clarify the mechanism of aneurysm growth by identifying significant hydrodynamic factors. We focus on a single ruptured aneurysm that was followed up for five years. Computer simulations and fluid dynamic experiments with silicone vessel models were performed. To confirm the reliability of data in the computer simulations, we conducted particle image velocimetry measurements in steady flow. We then performed computer simulations for pulsatile conditions to determine an effective index for aneurysm growth. We obtained good agreement between the trends in the obtained computer simulation and experimental data. Numerical simulations for pulsatile flow in three models revealed that aneurysms grew in regions having a low wall shear stress, a low aneurysm formation indicator, and a high oscillatory shear index.

We describe a patient with subcutaneous hematoma associated with manual cervical massage during carotid artery stenting. A 73-year-old man with left cervical carotid artery stenosis presented with left amaurosis fugax. We performed carotid artery stenting using distal embolic protection with balloon occlusion. Dual antiplatelet therapy was maintained in the periprocedural period and an anticoagulant agent was administered during the procedure. Because the aspiration catheter became entrapped by the stent, it did not reach the distal side of the stenotic lesion, and manual compression of the cervical region was therefore performed. Immediately afterwards, a subcutaneous hemorrhage occurred in the cervical region. There was no postoperative dyspnea due to enlargement of the hematoma, which was absorbed spontaneously. Cervical subcutaneous hematoma can occur in the cervical region due to cervical massage in patients who are receiving adjuvant antiplatelet therapy and anticoagulation therapy.

Real-time and accurate stress calculation in walls of vasculature is a desired goal in order to provide feedback control for catheter insertion robots without changing catheter stiffness and lumen. This feedback source also has applications in endovascular surgery simulation. In order to address this need, we consider photoelastic effect, as birefringence produced by light retardation relates to the stress inside photoelastic materials. In this research, a polariscope was designed for urethane elastomer vasculature models, the photoelastic coefficient of urethane elastomer was measured, and a camera system was calibrated to quantify and reduce error in the measurement system. An average error of 3.9% was found in stress measurements for the pressure range of 60-189 mmHg inside the urethane elastomer model. This result was applied to correct stress distribution images, using the average stress value as a reference and preserving local maxima and minima of stress. This enabled us to accurately calculate stress in vasculature models during human blood pressure simulation (HBPS), and enables the comparison, in a closed loop, of stress produced by HBPS and by catheter motion when driven by a robot, as well as to measure the stress produced by medical tools on the vascular model wall.

●Abstract● Purpose: We report two cases of acute ischemic stroke patients treated by additional thrombectomy using a basket-shaped microsnare (Soutenir) after infusion of intravenous recombinant tissue plasminogen activator (rtPA). Successful recanalization and good prognosis were achieved in both cases. Case 1: A 67-year-old man presented with left hemiplegia and agnosia. After completion of the intravenous rtPA infusion, he continued to show severe neurological deficit. Angiography revealed occlusion of the posterior trunk and a branch of the anterior trunk of the right middle cerebral artery (MCA). The two occluded arteries were successfully recanalized by removing the clot with Soutenir, resulting in neurological improvement. Case 2: A 49-year-old man presented with right hemiplegia and aphasia. After completion of the intravenous rtPA infusion, he continued to show severe neurological deficit. Angiography revealed occlusion of the left MCA at the proximal M1 segment. The occluded artery was successfully recanalized by removing the clot in the manner described above, resulting in neurological improvement. Conclusion: To our knowledge, this is the first report describing patients treated by additional thrombectomy using a Soutenir after failed intravenous infusion of rtPA. This procedure is a therapeutic option for selected acute ischemic stroke patients who are unresponsive to intravenous rtPA.

Human blood pressure simulation is of particular interest for artificial blood vessel evaluation in regenerative medicine, and for endovascular surgery simulation to become more realistic. Conventional pumps do not offer a solution for the flow quality requirements; therefore we propose a hybrid pump that combines the best properties of lobe and piston pumps. Feedback control was applied to the hybrid pump, the system was tested using three different waveforms as reference. One of the waveforms is a polynomial approximation of pressure variation inside a coronary artery; when used a realistic human blood pressure simulation was produced. A scaffold for blood vessel regeneration was evaluated with the simulated human blood pressure.

Recent advances in devices and materials, and therapeutic technical improvements in interventional neuroradiology practice make it possible to use this therapeutic method for the treatment of neurovascular disease. In view of the spread of this treatment and increasing numbers of the procedures, there is a social demand to maintain a certain therapeutic quality. One of the methods used to present the therapeutic quality of doctors to the public is technical and knowledge authorization by an official organization or society. According to the ideas of the Japanese Society of Neuro-Endovascular Therapy (JSNET) “The basic therapeutic standard should be secured by the Society to avoid unnecessary complications which are caused by improper techniques and immature experiences.” JSNET start to develop a Specialist Qualification System in 1997, and the first examination was held in 2002. Details of the development of the system and the requirement of specialists have previously been reported1. It has been ten years since development of this system and we have had eight examinations since 2002. Following six years of experience and two years of examinations using an animal model, we would like to introduce the JSNET Specialist Qualification System.

Endovascular intervention using interventional radiology (IVR) is most commonly used in cerebralvascular treatment. Medical imaging such as digital subtraction angiography (DSA) and vascular mapping make vasculature and catheters easier to read from fluoroscopy during endovascular intervention. We propose simulating IVR using augmented reality, reproducing fluoroscopic images and a patient-specific blood vessel model without X-ray imaging. The advantages of the patient-specific vascular model reproducing the human vasculature lumen with 13 μm resolution include 1) a realistic “feel,” 2) excellent tool behavior simulation during intervention, and 3) surgical training alternative to physician training in-vitro. Simulated fluoroscopic images are created in two steps: First, the blood vessel model refraction index is matched to surrounding glycerin solution to conceal the vascular model, making the silicone vasculature appear human as seen in endovascular intervention. Second, an augmented reality (AR) environment is created using image subtraction and overlap, making model-based endovascular simulation more understandable for catheter use and fluoroscopy use and reading.

Magnetic motion capture sensors (MMCS) are not commonly used for robot control due to the need for complex, resource-consuming calibration to correct error introduced by the magnetic sensor. We propose avoiding such calibration using a rule-based controller that only uses spatial coordinates from the magnetic sensor. This controller uses a sparse look-up table of spatial coordinates and actions conducted by the robot and reacts to the presence of the sensor near reference points. The control method was applied to manipulate a robotic camera to track a catheter-shaped sensor inside vessels silicone models. A second evaluation was done guiding a mechanism to reconstruct catheter insertion in major silicone vasculature models. The robotic camera tracked the catheter by reacting to the sensor within 10 mm of each reference point. The catheter insertion mechanism reconstructed the catheter trajectory by reacting to the sensor within 6 mm of each reference point. We found that the proposed method allowed robot control in a bounded space without having to correct for the magnetic tracker output distortion.

Background To date, no quantitative analysis has been developed to evaluate catheter performance inside the vascular lumen. Methods An evaluation system for endovascular tools was built with a polyurethane elastomer vascular model inside a polariscope and a catheter driving system. This robotic system reproduced a catheter insertion trajectory inside the vascular model, using a surgical catheter and three catheter prototypes used for motion capture on endovascular surgery simulation. Birefringence is produced by photo-elastic characteristics of the polyurethane elastomer when the material is submitted external stress. The birefringence produced by the catheter on the vascular model wall was recorded and represented numerically by the correlation between consecutive frames of the registered video. Results Correlation values between frames showed that the performance of the prototypes was lower than that of the medical use catheter. The performance of prototypes was reduced by microcoils on their tips. Conclusions This methodology opens new options to evaluate medical catheters and physicians skills. Copyright © 2008 John Wiley & Sons, Ltd.

Several advanced multiple catheter techniques have been invented for endovascular treatment. Stent-supported coil embolization is one of the most useful methods for wide neck aneurysms. We report 13 vertebral artery aneurysms treated with this method and discuss its efficacy. Between April 1999 and March 2006, we treated 13 patients with wide neck vertebral aneurysms, comprising 9 males and 4 females aged 38 to 79 (mean 60.0 years old) and treated with stent-supported coil embolization. Stent for coronary intervention was used in all cases. Using our original method, the microcatheter was inserted into the aneurysmal sac in advance, followed by deployment of the stent at the orifice. In this method, the microcatheter is placed out of the stent, which is useful to stabilize the microcatheter and to prevent the kick-back of microcatheter into the parent artery. Further, we repeated the inflation of balloon catheter at the orifice to prevent the coil herniation whenever placing coils. Complete obliteration of the aneurysm was achieved in 9 patients and subtotal occlusion in 4 patients. Two stents were needed in 1 patient because of stent migration into the aneurysm. A stent slipped down during withdrawal of the balloon catheter in 1 case without coil herniation or vessel injury. In follow-ups of 3 months to 7 years, there was no recurrence except for 1 case whose aneurysm regrew resulting in trapping of VA. The only procedure-related symptomatic complication was 1 case with transient abducens nerve palsy. Stent supported coil embolization for wide-based vertebral aneurysms is a very useful and valuable technique. It permanenty prevents coil herniation and the rectification of parent artery flow. Although sufficient results were initially obtained, long term follow-up should be carried out.

We treated ruptured intracranial aneurysms with endosaccular embolization using Guglielmi Detachable Coils (GDC) in 192 patients treated in Nagoya University and affiliated hospitals over the past 7 years. Hunt & Kosnik grading was I in 18 patients, II in 78, III in 51, IV in 38, and V in 7, respectively. One hundred and seven aneurysms were located in the anterior circulation and 85 in the posterior circulation. Complete obliteration was obtained in 105 (55%), subtotal in 76 (40%), and partial in 11 (5%) aneurysms. We experienced 27 intraprocedural complications, including 11 intraoperative ruptures and 16 thromboembolisms. Permanent morbidity and mortality related to the procedure were 4.7% and 2.1%, respectively. An analysis of complication cases based on the aneurysmal configuration and location showed that tiny aneurysms and vertebral aneurysms (VA-PICA) should be carefully treated to avoid possible perioperative hemorrhagic complications. Due attention should also be paid to thromboembolic complications on the treatment of aneurysms located in middle cerebral, basilar-tip and posterior inferior cerebellar artery because of its branching in close relationship to the aneurismal neck.

Background When resecting at falcine or parasagittal portion of paramedian meningiomas, intraoperative hemostasis often is difficult despite effective management of ipsilateral meningeal arteries. We attribute such difficulties to meningeal artery blood supply from the contralateral side. We retrospectively studied feeding arteries from both sides in case of paramedian meningioma in terms of patient and tumor characteristics. Methods Forty-three patients with paramedian meningiomas underwent selective internal and external carotid angiography. We investigated how contralateral meningeal arterial feeders related to patient profiles and imaging, histopathologic, and immunohistochemical findings. Results Contralateral meningeal supply existed for 14 of 25 falcine meningiomas and 6 of 18 parasagittal meningiomas. Patients with contralateral feeders were 8.5 years younger than the others ( P = .027) and were more likely to have larger tumors ( P = .028). These were histopathologically malignant ( P = .048), while showing more proliferation followed by monoclonal antibody against the Ki-67 antigen index ( P = .012) and angiogenetic potential associated with vascular endothelial growth factor expression ( P = .0085). Conclusions Contralateral meningeal supply may reflect strong angiogenetic recruitment from rapid tumor growth followed by high expression of vascular endothelial growth factor. This angiographical feature may predict the aggressive growth of paramedian meningiomas.

We propose an in vitro patient-specific anatomical model of the human cerebral artery and its simulation of endovascular intervention, a potent treatment modality for cerebrovascular diseases. Our proposed model reproduces the 3-dimensional vasculature lumen, using computed tomography (CT) and magnetic resonance (MR) fluoroscopic information, within a thin artery-like membranous configuration having material properties close to arterial tissue. This cerebral arterial model reproduces an exceedingly realistic surgical feel, dynamic vascular deformation and, other important aspects involving endovascular intervention, realizing a highly realistic surgical simulation. We also propose another vasculature model that reproduces the subarachnoid space around the cerebral arteries. This version simulates endovascular intervention realistically. The model is compatible with current major imaging modalities such as CT, MR, and transcranial Doppler (TDC), and should provide effective platforms for applications, such as diagnosis, surgical planning, medical training, hemodynamic analysis and medical system development and evaluation, especially surgical robots.

We reviewed 84 AVMs embolized over 7 years and studied the significance of the embolization for associated aneurysms. Out of 84 AVMs, 14 were preoperatively embolized and 66 were followed by radiosurgery. Ten intranidal aneurysms were found in 9 cases, all of which ruptured. Although 8 aneurysms were completely embolized, using glue, 2 incompletely treated aneurysms rebled. Out of 6 proximal feeder aneurysms, 3 ruptured ones were treated with detachable coils and have shown no rebleeding. The other 3 aneurysms that increased in size during the follow-up after the embolization of AVM were embolized without complications. Two flow-related aneurysms remained, and an AVM nidus was primarily treated. Both aneurysms disappeared after the embolization of AVM. The ruptured proximal feeder aneurysms located far from the nidus, which require another approach for the removal of AVM, should be embolized with coils to reduce surgical invasiveness. Embolization of intranidal aneurysms is very useful for the prevention of rebleeding, particularly in cases followed by radiosurgery. Among the flow-related aneurysm treatments, AVM may be the treatment of choice. As for the treatment strategy of AVM, it is important to detect and identify the associated aneurysms and treat them appropriately.

We investigated the indications for endovascular treatment of unruptured cerebral aneurysms based on the natural history reported in ISUIA and our treatment results. At Nagoya University hospital and affiliated hospitals over 7 years we treated or attempted embolization for 383 unruptured aneurysms, including 301 asymptomatic and 82 symptomatic ones. Among them, 326 were treated with embolization and 57 were left untreated due to the high risks involved. Ruptures during the follow-up occurred in 2 symptomatic cases without treatment. We experienced 28 technical complications including 9 hemorrhagic, 14 ischemic and 4 others at the intra- and perioperative stage, in addition to 14 recanalizations at the delayed stage. The rate of morbidity associated with procedure was 4.0%. There was a high risk of hemorrhagic complications from a tiny anterior communicating artery aneurysm and ischemic complications in the middle cerebral, basilar-tip, and vertebral dissecting aneurysms with a hypoplastic posterior inferior cerebellar artery. As for the symptomatic aneurysms, although 72 patients had a good outcome, symptoms due to mass effects did not improve in 19 cases and worsened in 7. Particularly large paraclinoid aneurysms with visual symptoms showed a reduced possibility of symptom improvement. Although embolization has proved highly effective for the treatment of unruptured aneurysms, the treatment decision should take into account the relevant guidelines, including those for surgical option and observation. Abbreviations: ISUIA: International Study of Unruptured Intracranial Aneurysms

Despite recent technical advances in embolization of cerebral aneurysms with platinum coils, some aneurysms eventually resulted in incomplete packing with remnant neck or dome filling. Such a situation with a remaining inflow zone may pose a risk of rupture and subsequent regrowth. Metals characteristically generate heat under high-frequency alternating magnetic fields (AMF). We used this property to induce local hyperthermia and promote thrombogenesis in incompletely packed aneurysms. Glass model aneurysms packed with coils were subjected to AMF to investigate the correlation between weight of platinum and temperature elevation and the correlation between flow rates of water through the model and temperature elevation. Next, activated coagulation time (ACT) of blood obtained from dogs was studied at various temperatures. Finally, side-wall aneurysms created in the canine carotid artery using a venous patch were packed with platinum coils. Change in temperature and angiographic changes were investigated after AMF application. In the glass model, the weight of platinum was correlated with elevation of temperature, and a negative logarithmic correlation was evident between flow rate and elevation of temperature. Elevation of blood sample temperature tended to shorten ACT. In canine carotid aneurysms, elevation of intra-aneurysmal temperature was confirmed and sufficient elevation of temperature was found to promote angiographically evident thrombogenesis of the remnant space after AMF application. Local hyperthermia may be useful in completing luminal obliteration of aneurysms after coil embolization. It may particularly useful for ruptured aneurysms to prevent the early rerupture.

The authors carried out a retrospective review of the records of 12 patients with aneurysms of the posterior cerebral artery (PCA). Four were asymptomatic, 1 presented with a mass effect, and 7 with a subarachnoid haemorrhage (SAH). Of the 7 ruptured aneurysms, 3 were embolized and 2 were clipped. However, 2 patients died from rebleeding before any treatment. Of the 5 unruptured aneurysms, 1 was embolized with coils but the remaining 4 have been conservatively observed. No aneurysms have ruptured during the follow-up period, and 3 have thrombosed spontaneously. According to our results, the PCA aneurysms should be treated aggressively in the early phase. Although the preservation of the anatomical integrity of the PCA should naturally be one of the prime objectives, PCA occlusion may sometimes be inevitable when treating large or fusiform aneurysms. On the other hand, conservative therapy is one of the options for the treatment of incidentally encountered unruptured ones, because these have the possibility of spontaneous thrombosis.

As the embolization of AVMs is often an adjuvant therapy combined with surgical extirpation or radiosurgery, the goal is to optimize the outcome of the following procedure. As the natural history of AVMs predicts a relatively low rate of neurological injury, the combined therapeutic modalities should have a low complication rate. We report the perisurgical complications of 66 AVMs and discuss techniques to avoid complications. Of the 66 patients treated with endovascular embolization, 14 subsequently underwent surgical resection and 43 had radiosurgery. Four patients obtained total occlusion of their AVM by embolization alone and required no further treatment. In 48 patients, more than 70% of the nidus was occluded with embolization. We observed 3 permanent and 9 temporary complications. Four complications occurred immediately after embolization, due to overembolization or thromboembolism. Seven delayed complications occurred, possibly due to retrograde thrombosis or a chemical reaction to the glue. In 4 of the 14 cases without AVM obliteration following embolization and radiosurgery, meningeal feeders developed or recanalized after the treatment with absorbable particles. We recommend embolization prior to radiosurgery to treat all fistulous and meningeal feeders and packing of the nidus with non-absorbable embolic materials. In 10 cases, repeat embolization achieved further nidus reduction prior ro repeat radiosurgery. Intranidal aneurysms that pose a high risk of bleeding were also embolized. To avoid complications with embolization, the AVM angioarchitecture, hemodynamics and functional location should be well recognized. Complications can be reduced with preoperative functional imaging, superselective angiograms, appropriate selection of embolic materials, and appropriate selection of embolization targets. The priority of vessels to be embolized is dictated by the subsequent treatment. Agressive embolization of high-risk vessels or those that will cause abrupt hemodynamic changes should be avoided.

We investigated the methods for treating arteriovenous malformations (AVMs) based on the clinical data and questionnaires sent to affiliated hospitals over 9 years. In 27 institutes, there were twice as many embolizations in the second half (5 years) than in the first half, and the overall clinical results improved especially in the latter half. Responses to a questionnaire on treatment strategy for 62 patterns of virtual AVMs simulating various types and situations were obtained from 17 institutes. There were three general strategies showing more than 70% consensus: 1) radiosurgery for small AVMs without bleeding; 2) embolization plus radiosurgery for large AVMs with ischemic events, and for large, eloquent ones and deep-seated ones with minor hemorrhage; 3) surgical removal for small, middle-sized AVMs with large hematoma except for middle-sized eloquent and deep-seated ones. The strategy used for high-grade AVMs with large hematoma was very different among the institutes. Generally, there is less aggressive surgical extirpation for difficult AVMs, and the dependence on radiosurgery with or without embolization seem to have become greater. The significance of embolization is that it makes the following treatments easier and more effective. Although the indication of radiosurgery is expanding based on its excellent results, embolization still plays a role to reduce the size and hemorrhagic risks and to eliminate factors unfavorable for radiosurgery.

For neck protection technique to prevent migration or protrusion of GDCs, non detachable balloons or microcatheters/wires are used. Non detachable balloon has good protective effect with great effect to the flow in the parent artery which is risky for safe procedure. Microcatheter has little effect to the parent flow and poor protective effect. We have developed retrievable microbasket for neck protective technique which can be delivered and retrieved through standard 18 catheters. These baskets have good protective effect in aneurysm model.

This study investigated the angiographic changes in embolised arteriovenous malformations (AVMs) pre- and post-embolisation and preradiosurgery to clarify the usefulness of embolisation as a pretreatment for radiosurgery and the strategy of embolisation for the radiosurgical success. A total of 37 patients with cerebral AVMs treated over a period of 4 years was investigated. All the AVMs were embolised with N-butyl cyanoacrylate and 2 months later they were treated by radiosurgery. The size of AVM nidus reduced just following the embolisation (mean 21.9 ml to 3.9 ml). The angiogram taken in preparation for radiosurgery showed a further size reduction in the nidus of 16 AVMs, no change in 10 and regrowth in 11. In all the cases where size was reduced, the nidus was densely packed, while all the regrown AVMs were of the diffuse type. Five AVMs disappeared following radiosurgery, all of which were size-reduction or no-change cases. In conclusion, to achieve success in subsequent radiosurgery, nidus embolisation and the occlusion of fistulous and meningeal feeders are mandatory. Imprudent proximal feeder occlusion and the use of embolic materials with a risk of recanalisation should be avoided to prevent regrowth of the nidus, which may lead to errors in planning the radiosurgery to follow.

Near-infrared spectroscopy was used to measure the relative concentration changes of oxygenated hemoglobin (HbO(2)), deoxygenated hemoglobin (HbR), and total hemoglobin (t-Hb) before, during, and after hyperventilation in eight patients with childhood moyamoya disease who underwent surgery. The patients were divided into the following two groups: those with and those without re-build-up phenomenon on electroencephalography. All patients except one exhibited decreased concentrations of HbO(2) and t-Hb during hyperventilation and decreased concentrations of HbO(2) and increased concentrations of HbR after hyperventilation. The difference between the hemoglobin concentration during and after hyperventilation was significantly greater in the group with the re-build-up phenomenon than the group without it (P0.03, Mann-Whitney U test). The patients with the re-build-up phenomenon had lower HbO(2) and higher HbR concentrations after hyperventilation. The concentrations of HbO(2) and HbR reflect an alteration in the oxygenated blood supply and/or oxygen use. Thus, it is strongly suggested that regional cerebral hypoxia and metabolic oxygen disturbances play an important role in the occurrence of the re-build-up phenomenon. Near-infrared spectroscopy is a useful noninvasive method to evaluate the efficacy of surgical treatment in childhood moyamoya disease.

In this paper, we focus on the problem of safety and operability which is involved in a teleoperation system (master slave system) for medical application, and propose a new control strategy to improve performance of safety and operability by two force display methods. One is a multiple sensor information display method which display several force information that are measured by several force sensors on one master device. The another one is a variable impedance characterization of master device which changes the impedance parameter of the master device according to the situation of the medical operation. We also apply this method to the neurosurgical telemedicine system, and perform an experiment to evaluate our method.

The treatment selection for cerebral arteriovenous malformation (AVM) still is in controversy. In order to find out the best way to treat AVM, we summarized the treatment result of AVM patients in our hospital. Sixty-three AVM patients who had been treated at Nagoya University Hospital since 1988 to 1997 were studied. The patient characteristics were nearly the same as other reported series. The treatment modalities include surgery, embolization and radiosurgery. Rate of nidus disappearance was assessed in each treatment. Highest rate was observed in surgery or surgery with embolization. But new neurological deficits were seen in 37% of the patients of same group. Nidus occlusion rate was not high in radiosurgery with embolization, but low in complication rate. The result showed the importance of embolization procedure in the treatment selection of AVM. The value of functional MRI as pre-therapeutic study is high in those patients whose AVM adjacent to eloquent area.

We treated 13 experimental wide-necked aneurysms of lateral type produced in dog carotid arteries with a vein-loaded stent system consisting of an autologous vein graft, a vein-carrier stent, and two other self-expanding Z-shaped stents. The vein-loaded stent, made by connecting the autologous vein graft to the vein-carrier stent, was implanted in the common carotid artery to seal the aneurysm's orifice, after which two booster stents were deployed. The distal stent was placed to fix the distal end of the vein graft, and the proximal stent was placed at the proximal venous portion of the vein-loaded stent to reinforce its proximal end. In this manner an intra-arterial bypass was established across the aneurysm. Of 13 aneurysms seven were completely occluded, preserving the parent artery. The remaining six procedures resulted in parent artery occlusion because of failures in stent deployment. Angiograms performed in within 1 week six successfully treated dogs revealed the parent artery to be patent in four but thrombosed in two. Histological study of successful cases showed as smooth intima with slight endothelial hypertrophy and partially organised thrombus. The intraluminal features were also observed with a vascular endoscope at the time of treatment in four dogs and at the time of follow-up angiography in two. The appearances corresponded well to the macroscopic findings in the specimens. Our vein-loaded stent system offers complete closure of the orifice, which does not occur with conventional stent placement. The method is believed to show clinical promise for treating wide-necked aneurysms not curable by embolisation of the sac.

We devised a vein-loaded stent system to immediately close the aneurysmal orifice without interrupting the parent arterial flow. Ten experimental wide-necked aneurysms located on canine common carotid arteries were treated with the implantation of a newly modified vein-loaded stent system. After deploying the stent, half of them were managed under administration of 50 mg of ticlopidine hydrochloride per day and the other half followed up without any anticoagulation therapy. Immediately after the stent placement, all aneurysms were completely obliterated with patency of the parent artery in the successfully implanted vessels in both groups. Follow-up angiography one week later disclosed complete occlusion of the aneurysm with patency of the parent artery in 67% (2/3) of the group with ticlopidine, while none of the group without drugs showed patency of the parent artery. The rate of patency of the parent artery was found to be improved by administration of ticlopidine, but was still lower than that of a conventional stent. Further modifications will be needed before clinical use.

We have treated 142 aneurysms with intrasaccular or parent artery occlusions. Selective intrasaccular occlusions were attempted on 109 cases. Total or subtotal saccular occlusion was achieved in 93 of 96 cases. Intrasaccular occlusion could not be achieved in 13 cases because of various reasons such as wide neck, branching from aneurysmal dome, difficult to catheterize, and aneurysm too small. Parent artery occlusion was attempted on 33 cases. Twenty-five patients had giant aneurysms of the internal carotid artery (ICA) at the cavernous portion. The rest of this group had dissecting or fusiform aneurysms of the vertebral artery. Parent artery occlusion was achieved in 30 cases with six ischemic symptoms. High percentage of occlusion rate and low morbidity and mortality for metallic coil embolization prove the efficacy of this endovascular treatment.

We aimed to identify anatomic factors favoring intra-aneurysmal clot embolization complicating coil embolization of basilar tip aneurysms. Thirty basilar tip aneurysm cases were classified angiographically into three types according to branching pattern of the superior cerebellar artery (SCA) and coil embolization complications were analyzed. The SCA may arise from the basilar artery (BA) just proximal to the origin of the posterior cerebral artery (PCA), initially coursing at an angle (more than 60°) relative to the BA, (type A). Alternatively the SCA may originate directly from the PCA at a sharp angle less than 30° relative to the BA (type C). Type B includes patterns intermediate between types A and C. Behavior of particles chosen to simulate intra-aneurysmal clots was also observed in a plastic tube model with pulsatile water flow simulating configurations A and C. Type C branching was seen in 35% (21/60) of SCA, being dominant on the left side and associated with large aneurysms and broad necks. All 3 of 24 coil embolization patients with ischemic complications in the SCA territory had large aneurysms and type C SCA branching, 2 aneurysms having broad necks. In the plastic model embolized “clots” more frequently lodged in type C than in type A SCA. “Clots” close to the orifice migrated more easily than those in the dome of the plastic aneurysm. Large basilar tip aneurysms with broad necks carry a risk of intra-aneurysmal clot migration into the SCA, during and after the embolization, especially in type C configurations, because pulsatile blood flow in the basilar artery may disperse clots between the coils and carry them into the sharply angulated SCA. Avoiding this complication requires meticulous coil packing to interrupt inflow into the aneurysm as well as appropriate anti-coagulation therapy.

We report a new treatment for excessive spasticity using an endovascular technique. A 52-year-old woman with intractable spasticity of the hip joints and abdominal muscles was treated with an injection of 70% alcohol into Adamkiewicz's artery, which destroyed the spinal cord fed by Adamkiewicz's artery and cut the reflex arcs of excessive spasticity. Immediately after the treatment a significant change was noticed in muscle tonicity of the lower extremities, and intractable spasticity disappeared. Skin necrosis and muscle damage occurred because of the alcohol that leaked into the muscle branch of the subcostal artery. However, these complications could be treated by simple necrotomy. No recurrence was observed during the follow-up period. We believe this endovascular treatment will become a new strategy for excessive spasticity arising from spinal cord injury.

In the wake of the SAPPHIRE trial1 and subsequent approval of carotid stenting (CAS) devices by the Food and Drug Administration (FDA) in the United States, CAS is poised to explode in the frequency of its application in North America. Although the results of the Carotid Revascularization Stenting versus Endarterectomy Trial (CREST), the largest randomized controlled trial comparing carotid endarterectomy to CAS, are years away, many practitioners in multiple disciplines have already entered the competition for patients and remuneration. Despite the absence of evidence to support CAS over carotid endarterectomy2,3 and the need to continue recruiting patients to CREST,4 cardiologists, vascular surgeons, neurologists, neurosurgeons, general interventional and neurointerventional radiologists are all vying to treat carotid stenoses, many of which are

An image guide for aneurysm embolization based on three dimensional CT angiography is reported. Multiplanner reformation (MPR) can measure the neck and dome of the aneurysm accurately enough to select the first coils for aneurysms. For neck evaluation, cut model and virtual endoscope are helpful because we can observe the neck from inside of dome or parent artery. Proximal arteries are visualized by 3D images and MPR if needed. Using laser lithography, we can get a real model of aneurysm and parent artery through which we can insert microcatheters and coils. 3D CTA is a dependable modality for embolization of cerebral aneurysms.

To prevent coil protrusion into the parent artery, the fluoroscopic view during coil packing is quite important. However it is not always easy to find out the optimal fluoroscopic view. We applied a rotation DSA to predict the optimal fluoroscopic view for the endovascular treatment of 4 cases with a cerebral aneurysm. Since the trajectory of the C-arm is restricted within 60 degrees only around the patient's head and the number of DSA shots are limited rather than conventional DSA, we employed three dimensional CT angiography (3D-CT angiography) to focus the range of C-arm rotation. Rotation DSA proved quite useful to determine the optimal fluoroscopic view, when combined with pre-estimation by 3D-CT angiography.

Hemodynamic factors are thought to play important role in the initiation, growth, and rupture of cerebral aneurysms. However, hemodynamic features in the residual neck of incompletely occluded aneurysms and their influences on recanalization are rarely reported. This study characterized the hemodynamics of incompletely occluded aneurysms that had been confirmed to undergo recanalization during long-term follow-up using computational fluid dynamic analysis. A ruptured left basilar-SCA aneurysm was incompletely occluded and showed recanalization during 11 years follow-up period. We retrospectively characterized on three-dimensional MR angiography. After subtotal occlusion, the flow pattern, wall shear stress (WSS), and velocity at the remnant neck changed during long-term follow-up period. Specifically, high WSS region and high blood flow velocity were found near the neck. Interestingly, these area of the remnant neck coincided with the location of aneurysm recanalization. High WSS and blood flow velocity were consistently observed near the remnant neck of incompletely occluded aneurysm, prone to future recanalization. It will suggest that hemodynamic factors may play important roles in aneurismal recurrence after endovascular treatment.

Measurement of cerebral blood flow in cerebral endovascular procedures is useful for the assessment of treatment effects. We used transcranial Doppler sonography (TCD) and Doppler guide wires (SmartWire®, Cardiometrics Co.) in intravascular treatment. The cases were 6 brain arteriovenous malformations (AVM), 2 carotid cavernous fistulas (CCF), 2 facial angiomas, and 2 carotid stenoses. Intravascular cerebral blood flow measurements with the SmartWire were performed during the endovascular procedure. TCD was used pre- and post-endovascular treatment, and velocity, pulsatility index (PI) and resistance index (RI) were compared with the SmartWire. For both TCD and SmartWire, blood velocity of the main artery decreased, and PI and RI were improved after embolisation of AVM. In angioplasty cases, post stenotic flow velocity, as measured by SmartWire, was improved, and the flow of MCA measured with TCD was also improved after treatment. The SmartWire is useful to assess cerebral blood flow changes during the neuroendovascular procedure. Combined with repeated follow up with TCD, Doppler flow measurements are useful to assess the effect of endovascular treatment.

Recently, the catheter has been down-sized and has become functional, and it has begun to be used for practical medical operations. Nowadays intravascular neurosurgery using the catheter is carried out for an aneurysm or cerebral thrombosis. However, it is quite difficult to select the direction at a divergence point because brain blood vessels are narrow and complex. For this reason, an active catheter whose tip can be actuated by a microactuator is studied and developed. Even if the active catheter is realized, its control is very difficult. Therefore we investigate an assistance system for the doctor operating the active catheter. In this paper, we propose the concept of an intelligent medical assistance system for operation of the active catheter. To realize this medical assistance system, we built a prototype of a virtual simulator system consisting of an active joystick, which has force feedback capability, and a 3D-computer graphics display. Using this simulator system, we evaluated the effectiveness of the proposed visual and operation assistance methods through extensive experiments.

For the development of artificial intelligent diagnosis for cerebrovascular intervention, it is desirable to forecast the growth of cerebral aneurysms. In order to achieve such purpose, it is needed to evaluate wall shear stress, strain, pressure, deformation and flow velocity in the aneurysm region. In this research, we focus on in-vitro strain and deformation measurements of cerebral aneurysm models, and propose a cyber-physical system, in which a scaled-up membranous silicone model of cerebral aneurysm was built and integrated with a specialized pump for the pulsatile blood flow simulation, and a vision system was constructed to measure the strain on different regions on the model with pulsatile blood flow circulated inside. Experimental results show that both distance and area strain maxima were larger for the aneurysm neck (0.042 and 0.052), followed by the aneurysm dome (0.023 and 0.04) and then by the main blood vessel section (0.01 and 0.014), which were complemented with computer fluid dynamics simulation for the inclusion of wall shear stress, oscillatory shear index and aneurysm formation index. Medical imaging data of the cerebral aneurysm in 2008 and 2011 was obtained. Diagnosis results have concordance with the aneurysm growth in 2011. The presented measurement method offers an option for measuring strain and deformation to be complementary with computer fluid dynamics and photoelastic stress analysis for advanced diagnostic in the endovascular surgery.

Quantification of human skills is a challenge for simulator based medical training, particularly for endovascular intervention. For that purpose it is needed to measure different biometric parameters from the user and additionally measure the interaction between endovascular instruments and vasculature models membrane. For that purpose in this research we present an optical sensor for encoding linear and rotational motion of the catheter through the insertion port. Additionally we present two studies for measuring tissue integrity, time to complete a task, reaction time, and wasting motion using two populations of expert and beginner. The optical encoder showed an average error of 0.39mm and 10.78deg. In both studies the presented cyber-physical system is useful to identify the users with qualities closer to the expert among users with low performance.

Computer based simulation is important for clarifying the hemodynamics in brain aneurysm. Specifically, for endovascular treatments, the effect of indwelling intravascular devices on blood stream needs to be considered. Most recent technology for cerebral aneurysm treatment is related with the use of flow diverters to reduce the amount of flow entering to the aneurysms. In this research, we present a new method for design of flow diverters and fitting them to patient specific vasculature models. This methodology enables to change porosity of the flow diverters as well as their location in the blood vessel. One coiling assist stent and two flow diverters were compared to estimate the effect of flow alteration in aneurysm for treatment of a cerebral aneurysm. From the numerical result, we can conclude that pore density and size of mesh affect the hemodynamics in aneurysm and high density and small size of pore produce reduction effect of pressure and wall shear stress on an aneurysm.