Masaki Ebara

Unruptured Intracranial Aneurysms Incidence of Rupture and Risk Factors

Backgrounds and Purpose— The authors evaluated the incidence of rupture of unruptured intracranial saccular aneurysm during observation. Methods— Between January 2003 and December 2006, a total of 419 patients with 529 unruptured intracranial saccular aneurysms were observed without treatment. The mean follow-up duration was 905.3 days. Aneurysm size was measured by 3-dimensional CT angiography. Clinical and 3-dimensional CT angiography follow-up were obtained every 6 months. Results— Nineteen aneurysms ruptured during observation resulting in a 1.4% rupture rate per year. A history of subarachnoid hemorrhage (hazard ratio, 7.3; 95% CI, 2.5 to 21.2), posterior circulation aneurysm (hazard ratio, 2.9; 95% CI, 1.1 to 8), and large size were significant independent predictors for aneurysm rupture. Conclusions— Size, history of subarachnoid hemorrhage, and posterior circulation aneurysms were significant risk factors for prediction of rupture of unruptured intracranial saccular aneurysms.

Risk Analysis of Unruptured Intracranial Aneurysms: Prospective 10-Year Cohort Study.

Background and Purpose— The natural history of unruptured intracranial aneurysms remains unclear, and management strategy is not well defined. Methods— From January 2003 to December 2012, we enrolled patients with aneurysm in our institution. In total, 2252 patients with 2897 aneurysms were eligible for analysis, and 1960 eligible aneurysms were conservatively managed. Precise 3-dimensional evaluation was conducted using computed tomography angiography, digital subtraction angiography, or magnetic resonance angiography. We then assessed the risk of aneurysm rupture, mortality, and morbidity associated with aneurysm characteristics, demographics, and known health/lifestyle risk factors. Results— The mean follow-up duration was 7388 aneurysm-years. During observation, 56 aneurysms ruptured, resulting in an overall rupture rate per year of 0.76% (95% confidence interval, 0.58–0.98). The mean initial visit to rupture interval was 547 days. Aneurysm size, location, daughter sac, and history of subarachnoid hemorrhage were significant independent predictors for aneurysm rupture. Aneurysms that were ≥5 mm were associated with a significantly increased risk of rupture when compared with 2- to 4-mm aneurysms (unadjusted hazard ratio, 12.24; 95% confidence interval, 7.15–20.93). Of 56 patients who experienced hemorrhage, 29 (52 %) died or were rendered severely disabled. Of the patients who had large or giant aneurysms, none recovered without deficits, and the mortality rate after rupture was 69%. For aneurysms sized <5 mm, the mortality rate was 18%. Conclusions— Larger aneurysms are at greater risk for rupture and poor outcome. Ethnic factors may play a role in the risk of rupture.

Robotic digital subtraction angiography systems within the hybrid operating room.

BACKGROUND:Fully equipped high-end digital subtraction angiography (DSA) within the operating room (OR) environment has emerged as a new trend in the fields of neurosurgery and vascular surgery. OBJECTIVE:To describe initial clinical experience with a robotic DSA system in the hybrid OR. METHODS:A newly designed robotic DSA system (Artis zeego; Siemens AG, Forchheim, Germany) was installed in the hybrid OR. The system consists of a multiaxis robotic C arm and surgical OR table. In addition to conventional neuroendovascular procedures, the system was used as an intraoperative imaging tool for various neurosurgical procedures such as aneurysm clipping and spine instrumentation. RESULTS:Five hundred one neurosurgical procedures were successfully conducted in the hybrid OR with the robotic DSA. During surgical procedures such as aneurysm clipping and arteriovenous fistula treatment, intraoperative 2-/3-dimensional angiography and C-arm-based computed tomographic images (DynaCT) were easily performed without moving the OR table. Newly developed virtual navigation software (syngo iGuide; Siemens AG) can be used in frameless navigation and in access to deep-seated intracranial lesions or needle placement. CONCLUSION:This newly developed robotic DSA system provides safe and precise treatment in the fields of endovascular treatment and neurosurgery.

Dynact soft-tissue visualization using an angiographic C-arm system: initial clinical experience in the operating room.

INTRODUCTION DynaCT is a clinical application protocol to create computed tomographic (CT)-like images allowing soft-tissue visualization acquired from an angiography system. A cone beam three-dimensional CT reconstruction is produced from the acquisition of two-dimensional projection images by rotating the c-arm with x-ray source and image receptor around the patient. The purpose of this study is to evaluate the clinical efficacy of DynaCT in the operating room. METHODS DynaCT was performed in 100 patients undergoing cerebral or spinal interventional procedures in the new-concept operating room. Specially designed AXIOM Artis BA (conventional image intensifier system; 55 patients; Siemens Medical Solutions, Erlangen, Germany) and AXIOM Artis dBA (flat-panel detector; 45 patients; Siemens Medical Solutions) biplane neuroangiographic systems (Siemens Medical Solutions, Germany) were installed in the operating room. The volumetric data set from the AXIOM Artis systems were reconstructed immediately on the three-dimensional workstation in the operating room. We compared DynaCT images with the use of multidetector computed tomography. RESULTS DynaCT was performed successfully in all patients. High-contrast structures, such as bone, calcified lesions, and metallic materials, were visualized on DynaCT as well as in multidetector computed tomography for each group. Although contrast differentiation of soft tissue such as cerebral cortex, muscle, and hematoma on DynaCT were inferior to multidetector CT scans, the images were sufficiently used as intraoperative CT-like images. However, DynaCT images acquired from flat panel detector-based systems were found to be superior to those images acquired from image intensifier-based systems. Striking ring artifacts were exhibited and resulted in major limitations in the image intensifier group. CONCLUSION DynaCT has the potential to be used as a powerful tool for endovascular and neurosurgical procedures and will open new possibilities for neurosurgical management.

Neuroendoscopic placement of Ommaya reservoir into a cystic craniopharyngioma.

Abstract Introduction. Total removal of the tumor is the most acceptable therapeutic modality in the management of craniopharyngioma; however, there are innumerable factors that can upset treatment plans. Unresectable lesions are often treated with gamma knife surgery (GKS). Reduction of the cystic volume is necessary, to decrease the area to be treated with GKS. An Ommaya reservoir system is usually placed during open surgery or by stereotactic access. Materials and methods. The authors use a neuroendoscope for safer and less invasive placement of the Ommaya reservoir into deep-seated cystic lesions. The cystic component is aspirated, and the Ommaya reservoir tube is precisely guided and placed into the cyst cavity under neuroendoscopic control with a newly developed two-burr-hole technique. This neuroendoscopic procedure could make it easier to reduce cystic volume prior to GKS as the final procedure. This technique may also be used for instillation of chemotherapeutic agents and for repeat aspirations, making the achievement of cystic control more likely. This type of neuroendoscopic management is a safe and effective procedure and could be considered as an alternative management technique for some stubborn cystic craniopharyngiomas.

Combined surgical and endovascular treatment of complex cerebrovascular diseases in the hybrid operating room

Background Although most neurovascular diseases can be treated either by microsurgical or endovascular means, a subset of patients may require a combined approach. Patient transfer from the operating room (OR) to the angiosuite has been a fundamental drawback of this type of approach. Objective The purpose of this study is to report our clinical experience performing combined surgical and endovascular procedures for neurovascular diseases in the hybrid OR. Methods 29 patients with neurovascular diseases underwent combined endovascular and surgical procedures in a single session: 16 were scheduled combined treatment and 13 were emergency combined procedures. Of the emergency cases, three were rescue surgeries after endovascular complications. Three patients had ruptured intracranial aneurysms, eight had unruptured intracranial aneurysms, eight had arteriovenous malformations and eight had arteriovenous fistulae; two patients had either a spinal tumor or dural arteriovenous fistulae. Results All combined procedures were performed in a single session without changing the patients surgical position. In cases of ruptured arteriovenous malformations or aneurysms with hematoma, an emergency embolization was performed to assist the surgical procedure. Combined superficial temporal artery–middle cerebral artery (STA–MCA) bypass followed by endovascular parent artery trapping were successfully performed for complex large or giant aneurysms. There were two periprocedural ischemic complications. Of the three patients who underwent surgical rescue after endovascular complications, two remained intact and one died despite immediate surgical procedures. Conclusion A combined endovascular and surgical approach conducted in a hybrid OR provides a new strategy for the treatment of complex neurovascular diseases.

Endovascular treatment of experimental aneurysms using a combination of thermoreversible gelation polymer and protection devices: feasibility study.

OBJECTIVEWe developed a new liquid embolic agent, an aqueous solution of thermoreversible gelation polymer (TGP) for the treatment of cerebral aneurysms. This polymer solution has the unique characteristics that allow it to solidify at a specific temperature without solvent. We performed an experimental aneurysm embolization using this liquid embolic agent with and without different protective devices to evaluate its technical feasibility for the treatment of aneurysms. METHODSFourteen side-wall aneurysms were surgically constructed on 14 common carotid arteries of 7 swine. Embolizations were conducted in combination with balloon protection (balloon group, n = 4), microstent protection (stent group, n = 4), and microcoil and microstent protection (stent-coil group, n = 4). Two aneurysms were used as controls. One control aneurysm was not embolized, and the other received control stent placement only. Angiographic follow-up was performed on day 14 and was followed by histopathological evaluation. RESULTSSuccessful TGP solution delivery was conducted in all cases. Complete aneurysm occlusion was achieved in all cases without TGP migration. Follow-up angiograms demonstrated complete occlusion in the stent and stent-coil groups. A small recurrence was observed in the balloon group. Histopathological findings demonstrated neoendothelialization across the necks of the aneurysms. CONCLUSIONExperimental aneurysms were safely embolized using TGP. Further modifications related to mechanical stability and long-term safety evaluation results are necessary before clinical application.

Natural Course of Dissecting Vertebrobasilar Artery Aneurysms without Stroke

More than 100 conservatively managed nonstroke dissecting vertebrobasilar artery aneurysms were followed on average for 3 years. Ninety-seven percent of patients remained clinically unchanged and the 3 patients who deteriorated clinically had aneurysm enlargement. The natural course of these lesions suggests that acute intervention is not always required and close follow-up without antithrombotic therapy is reasonable. Patients with symptoms due to mass effect or aneurysms of >10 mm may require treatment. BACKGROUND AND PURPOSE: The natural history and therapeutic management of dissecting vertebrobasilar aneurysms without ischemic or hemorrhagic stroke (nonstroke dissecting vertebrobasilar aneurysms) are not well-established. We conservatively followed patients with nonstroke dissecting vertebrobasilar aneurysms and evaluated the factors related to clinical and morphologic deterioration. MATERIALS AND METHODS: One hundred thirteen patients were enrolled and divided by clinical presentation at diagnosis: asymptomatic (group 1, n = 52), pain only (group 2, n = 56), and mass effect (group 3, n = 5). Patients were conservatively managed without intervention and antithrombotic therapy. Clinical outcomes and morphologic changes were analyzed. RESULTS: A total of 113 patients who were diagnosed with nonstroke dissecting vertebrobasilar aneurysm had a mean follow-up of 2.9 years (range, 27 days to 8 years). Throughout that period, 1 patient in group 1 (1.9%) and 1 patient in group 2 (1.8%) showed clinical deterioration due to mass effect, and 1 patient in group 3 (20%) developed ischemic stroke followed by subarachnoid hemorrhage. Most patients (97.3%) were clinically unchanged. Three patients who had clinical deterioration showed aneurysm enlargement (P < .001). Aneurysms remained morphologically unchanged in 91 patients (80.5%). Aneurysm enlargement was seen in 5 patients (4.4%); risk of enlargement was significantly associated with either maximum diameter (hazard ratio = 1.30; 95% CI, 1.11–11.52; P = .001) or aneurysm ≥10 mm (hazard ratio = 18.0; 95% CI, 1.95–167; P = .011). CONCLUSIONS: The natural course of these lesions suggests that acute intervention is not always required and close follow-up without antithrombotic therapy is reasonable. Patients with symptoms due to mass effect or aneurysms of >10 mm may require treatment.

Validation and Initial Application of a Semiautomatic Aneurysm Measurement Software: A Tool for Assessing Volumetric Packing Attenuation

BACKGROUND AND PURPOSE: Precise aneurysm measurements and volume embolization ratios are essential for long-term durability of endovascular coil embolization. We evaluated the accuracy of newly developed semiautomatic cerebral aneurysm measurement software, NeuroVision, and explored the value of volume embolization ratio in the prediction of re-treatment. MATERIALS AND METHODS: We compared software-derived volume measurements of 4 silicone aneurysm models with those calculated with an approximation formula and ground truth values (validation study). We used NeuroVision to retrospectively evaluate outcomes of 100 unruptured aneurysms (97 patients) treated with embolization (clinical study). Aneurysm size (height, width, and neck), volume, and volume embolization ratios were calculated for 3 groups (stable, recanalization, and re-treatment) and were compared. RESULTS: This validation study illustrated higher accuracy of NeuroVision in computing aneurysm volume compared with an approximation formula: percentage absolute errors were 4.50% ± 3.18% and 23.07% ± 17.60%, with maximal percentage absolute errors of 8.99% and 45.63%, respectively. Of 100 unruptured aneurysms, 20 recanalized and 12 were re-treated. Average volume embolization ratios of stable and re-treated aneurysms were 24.88% ± 5.91% and 20.50% ± 4.06%, respectively (P ≤ .01). The optimal volume embolization ratio cutoff point for re-treatment was < 19.15%, at which the Youden index was 0.50 (sensitivity, 58.33%; specificity, 87.50%; area under the receiver operating characteristic curve, 0.74). CONCLUSIONS: The NeuroVision software provided accurate aneurysm volume measurements and may be a useful standardized tool to measure aneurysm size and volume, especially for multicenter clinical studies. Volume embolization ratio may be a valuable predictor of aneurysm occlusion changes.

Delayed hydrocephalus after embolization of unruptured aneurysms using bare platinum coils: report of 2 cases.

SUMMARY: Postembolization hydrocephalus with bare platinum coils has not been reported, to our knowledge. We report 2 cases of unusual delayed hydrocephalus after treatment of unruptured intracranial aneurysms with bare platinum coils.