Objective: This study was designed to develop a new hemodynamic parameter on the computational fluid dynamics (CFD) analysis using porous media modeling to predict the angiographic occlusion status after coil embolization of unruptured cerebral aneurysms preoperatively.
Method: From September 2009 to June 2013, we treated 20 unruptured cerebral aneurysms with intra-aneurysm coil embolization. Aneurysms were classified into complete occlusion (n=11) or residual flow (n=9) groups based on the angiographic appearance performed at 6–12 months post-coiling. For each aneurysm, a preoperative patient-specific geometry was obtained after segmentation using the DICOM dataset of 3D rotation angiography or 3D CT angiography. With the assumption that coil fibers were randomly distributed in the dome, filtration of blood through a virtual coil-filled aneurysm was described by Darcy's law (porous media modeling), and a new hemodynamic parameter, residual flow volume (RFV), was calculated using CFD analyses. Other hemodynamic parameters such as wall shear stress (WSS) and inflow area (IFA) were also calculated by the CFD analysis. The CFD simulation was achieved using both pre-coiling aneurysm models and virtual coil-filled aneurysm models (porous media modeling). Morphological parameters, volume embolization ratio (VER), and hemodynamic parameters were compared between the complete occlusion and residual flow groups. The area under the receiver operating characteristic (ROC) curve (AUC) was used to examine the diagnostic accuracy to predict the 6–12-month post-coiling angiographic results of aneurysms.
Result: There were no significant differences in VER and WSS between the two groups. Among morphological parameters, neck diameter (P=0.020) and neck area (P=0.025) were significantly larger in the residual flow group. Among hemodynamic parameters, IFA in the pre-coiling aneurysm model (P=0.014) and RFV in the coil-filled aneurysm model (P=0.011) were significantly larger in the residual flow group. The ROC analyses showed that RFV with an average flow velocity of more than 1.0 cm/sec in the aneurysm dome (RFV_1.0) was useful to predict the post-coiling aneurysm occlusion status (AUC, 0.84 [95% confidence interval, 0.64–1.00]; cut-off value, 10.6 mm³; sensitivity, 100%; and specificity, 63.6%).
Conclusion: CFD analysis using porous media simulation may be useful to predict the post-coiling aneurysm-occlusion status. This study proposed a new hemodynamic parameter, RFV_1.0, on the CFD analysis, which potentially affects the treatment strategy because the parameter can be simulated before coiling of aneurysms.

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Objective: We report a case of dural arteriovenous fistula (DAVF) of the sinus confluence treated with surgical transvenous embolization by direct puncture of the superior sagittal sinus (SSS).
Case presentation: A 34-year-old man complained of tinnitus and diplopia. Cerebral angiography showed aggressive DAVF involving the bilateral transverse-sigmoid sinus, the SSS, and the sinus confluence with severe cortical and deep venous reflux. We performed transarterial and transvenous embolization for the transverse-sigmoid sinus lesions at first. The feeding posterior meningeal arteries were collected into the sinus pouch of the confluence with the strong upward blood flow to the SSS in a retrograde fashion. A catheter from the femoral vein never got into the sinus pouch. Therefore we performed a small craniotomy on the frontal midline and the distal SSS was directly punctured to navigate a microcatheter to the pouch, which was obliterated completely with coils. Thus the shunt flow was significantly decreased.
Conclusion: This surgical transvenous approach with a direct puncture of the SSS was a unique and an effective way for the treatment of DAVF of the confluence.

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Objective: Traumatic arteriovenous fistula (AVF) concomitant with pesudoaneurysm involving the middle meningeal artery is uncommon. Traumatic AVF is also known to occasionally show spontaneous closure. We report a rare case of traumatic pseudoaneurysm of the middle meningeal artery identified after spontaneous closure of a traumatic AVF.
Case presentation: A 36-year-old right-handed man suffered a head injury after falling from a step at home, and was brought to our institute. The patient showed no neurological deficits. Computed tomography (CT) showed no intracranial hemorrhage and he was discharged to home. Six days later, he consulted our outpatient clinic because of dizziness and pulsatile tinnitus on the right side. Fracture in the right temporal bone was found on review of the initial CT. Magnetic resonance (MR) imaging showed cerebral contusion in the left temporal lobe and MR angiography demonstrated AVF involving the middle meningeal artery. Angiography revealed direct AVF supplied by the dilated right middle meningeal artery and draining into the cavernous sinus with no cortical venous reflux. Transarterial embolization was attempted 56 days after head injury. Right external carotid artery angiography revealed spontaneous obstruction of the AVF. Selective middle meningeal artery angiography disclosed a small aneurysm, which was embolized completely by coils and glue material.
Conclusion: It may be sometimes difficult to detect a traumatic pseudoaneurysm associated with a traumatic arteriovenous fistula of the middle meningeal artery. Close radiographical follow-up is necessary in this lesion.

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Objective: The inferior petrosal sinus (IPS) provides the best access route to the cavernous sinus in transvenous embolization (TVE) of cavernous sinus dural arteriovenous fistula (CS-dAVF). However, some cases require other access routes. We describe a case of CS-dAVF successfully treated with TVE via the superficial temporal vein (STV) from the common femoral vein.
Case presentation: The patient was an 82-year-old woman with conjunctival hyperemia and exophthalmos of the left eye due to a left CS-dAVF. A cerebral angiogram showed that the IPS had occluded and the superior ophthalmic vein, middle temporal vein (MTV), and STV had dilated as the main drainer. We had planned to reach the CS via the IPS but were forced to abandon that route because it was not possible to guide the microcatheter into the CS. We therefore attempted to use the STV for access. On the first attempt, we had difficulty in inserting the microcatheter through the tortuous section between the MTV and STV. We were able to achieve passage with manual progress by epidermal compression. Finally, we successfully guided the microcatheter to the shunted pouch and targeted embolization was performed.
Conclusion: Accessing the CS via the STV can be an option when TVE via the IPS is not possible in a patient with CS-dAVF.

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Objective: Contrast agent neurotoxicity is a rare complication of neurovascular intervention. Here we report two cases of symptomatic contrast-induced encephalopathy after coil embolization for unruptured cerebral aneurysms.
Case presentation: A 75-year-old man with right unruptured anterior cerebral artery aneurysm and a 65-year-old woman with left unruptured internal carotid artery aneurysm underwent endovascular coil embolization. Immediately after the procedure, the male patient showed left hemiparesis, and the female patient showed right hemiparesis and aphasia. Non-contrast computed tomography (CT) showed cortical enhancement in the affected cerebral hemisphere immediately after the procedure and complete resolution of the abnormal findings the next day. Magnetic resonance imaging revealed a few small infarctions that were not considered responsible for the neurological symptoms. Clinical symptoms resolved completely within 3 days after procedures using only conservative therapy. Therefore, both patients were diagnosed with contrast-induced encephalopathy.
Conclusion: Although the precise mechanisms underlying contrast-induced encephalopathy remain unclear, one possible reason for this complication is osmotic disruption of the blood-brain barrier. Endovascular neurosurgeons should be aware of this rare complication during and after endovascular treatment.

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Objective: We report a case of hemorrhagic vertebral artery dissecting aneurysm (VADA) treated with sole stenting technique.
Case presentation: A 39-year-old man developed severe headache and alteration of consciousness due to thick subarachnoid hemorrhage. Computed tomographic angiography (CTA) demonstrated right hemorrhagic VADA. Poor collateral flow under balloon occlusion in the right vertebral artery (VA) was also detected. We used the sole stenting technique for right hemorrhagic VADA both to prevent aneurysmal rebleeding and to avoid parent artery occlusion. Flow stagnation was achieved within the aneurysmal sac by using two balloon expandable coronary stents (stent-in-stent). No ischemic or hemorrhagic complications were observed. The patient was transferred to rehabilitation hospital. Angiography after 10 months showed complete obliteration of aneurysm and no recurrence was achieved for 3 years.
Conclusion: The sole stenting technique could effectively treat hemorrhagic VADA.

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Objective: Proximal balloon protection (PBP) in carotid artery stenting via the transbrachial carotid artery stenting (TB-CAS) approach has not been feasible because a large-sized sheath introducer is required. We report a novel technique of TB-CAS using sheathless balloon guiding catheter navigation.
Case presentation: A 76-year-old male presented with a symptomatic left internal carotid artery stenosis. Transfemoral approach was difficult because of severe arteriosclerosis obliterans. A 9Fr Optimo 90 cm was inserted into the right brachial artery over a 6Fr long dilator 108 cm by the coaxial method without sheath introducer, and it was advanced into the right subclavian artery. A long dilator was exchanged with an inner catheter and a 9Fr Optimo was navigated into the common carotid artery by using the telescoping technique. Further procedures were successfully performed by PBP using a 9Fr Optimo. The patient's postoperative course was uneventful, and follow-up head MRI did not reveal any distal embolization.
Conclusion: This technique is useful in high-risk patients of distal thromboembolic complication in CAS with difficult femoral access, because it enables PBP by TB-CAS.

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Objective: We describe two cases of left carotid artery stenting (CAS) via transbrachial artery approach by using coaxial system with an ASAHI FUBUKI Dilator 6Fr and an ENVOY Simmons 6Fr.
Case presentation: Two patients with symptomatic left carotid stenosis were treated with CAS via the transbrachial artery approach. By using coaxial system with an ASAHI FUBUKI Dilator 6Fr 80 cm and an ENVOY Simmons 6Fr 100 cm, an ENVOY Simmons 6Fr was placed into the left common carotid artery (CCA). Next, after a 0.035-inch halfstiff type guidewire was navigated into external carotid artery, an ASAHI FUBUKI Dilator 6Fr alone was advanced into the left CCA. CAS was performed by using distal filter protection method. There was no residual stenosis of the lesion after CAS.
Conclusion: A navigation of guiding sheath by using coaxial system with an ASAHI FUBUKI Dilator 6Fr and an ENVOY Simmons 6Fr was effective in left CAS via transbrachial artery approach.

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