AB028. Precision neurosurgery for brain tumors using robotic navigation under exoscope.

BACKGROUND: Three-dimensional (3D) exoscope and navigation systems have recently become remarkably advanced in neurosurgery. Robotic navigation is being used in various facilities. Based on the created surgical plan, robotic navigation automatically determines the path to guide the instrument. It seamlessly integrates with continuous real-time navigation and robotic alignment functions to improve the efficiency of intraoperative workflow and support highly accurate positioning. We have achieved good results in surgeries utilizing robotic navigation at our institution, and we report on the results and prospects. METHODS: At our hospital, 15 patients underwent surgery using Stealth AutoguideTM (Medtronic) in conjunction with the StealthStation S8 (Medtronic). The mean age was 56.2 years; 10 were men, and five were women. We used the exoscopic systems with KINEVO 900 (Zeiss) or ORBEYE (Olympus). RESULTS: The cases comprised of 11 gliomas, two primary central nervous system lymphomas, one germ cell tumor, and one brain abscess. Seven biopsies (six burr holes, one craniotomy) and six fence posts were used for Stealth AutoguideTM, tubing in two cases. Biopsies were performed quickly and reliably. In the cases where fence posts were used, it was possible to position the post quickly on the target and place it accurately in the planned area to determine the extent of removal. In addition, using the 3D exoscope system allowed the surgeon to simultaneously view the operating field and navigation screen without moving the surgeon's line of sight, making the operation safer. CONCLUSIONS: Surgery using robotic navigation was performed safely and efficiently, and highly accurate positioning was achieved regardless of the surgical technique. This system is expected to continue improving the accuracy, safety, and reproducibility of surgery and reducing the burden on the patient.

Utility of catheter-shaping using mixed-reality devices in cerebral aneurysm coil embolization.

BACKGROUND: Catheter shaping is vital in cerebral aneurysm coil embolization; however, understanding three-dimensional (3D) vascular structures on two-dimensional screens is challenging. Although 3D-printed vascular models are helpful, they demand time, effort, and sterility. This study explores whether mixed-reality (MR) devices displaying 3D computer graphics (3D-CG) can address these issues. METHODS: This study focused on magnetic resonance imaging (MRI) of seven cases of cerebral aneurysms. Head-mounted display (HMD) and spatial reality display (SRD) MR devices were used, and applications for 3D-CG display at a 1:1 scale and a 3D-CG control panel were developed. Catheters shaped using a 3D printer, HMD, and SRD were inserted into hollow models to assess their accessibility and positioning. RESULTS: The concordance rate of the 3D printer and HMD groups in terms of accessibility to the aneurysm was 71.4 %, while that of the 3D printer and SRD group was 85.7 %, and that of the HMD and SRD group was 85.7 %. The concordance rates of positioning in the 3D printer and HMD groups, 3D printer and SRD groups, and HMD and SRD groups were 85.7 %, 85.7 %, and 100 %, respectively. CONCLUSIONS: MR devices facilitate catheter shaping in cerebral aneurysm coil embolization and offer a time-efficient, precise, and sterile alternative to traditional 3D printing methods.

Dolichoectasia of the ophthalmic artery: a case report on the treatment strategy in endovascular therapy and literature review.

BACKGROUND: Dolichoectasia is a rare arterial condition characterized by the dilatation, tortuosity, and elongation of cerebral blood vessels. The vertebrobasilar artery and internal carotid artery are the common sites of dolichoectasia. However, dolichoectasia of the branch arteries, such as the ophthalmic artery (OA), is extremely rare. To the best of our knowledge, this is the first case of ophthalmic dolichoectasia that was successfully treated with endovascular internal coil trapping. CASE PRESENTATION: A 54-year-old female patient presented with transient left ophthalmalgia and visual disturbance. Magnetic resonance imaging revealed a dilated and elongated left OA compressing the optic nerve at the entrance of the optic canal. However, a previous image that was taken 17 years back revealed that the OA was normal, which suggested the change in dolichoectasia was acquired. Cerebral angiography showed that the dilated and tortuous OA was running from the ophthalmic segment of the left internal carotid artery into the orbit. The symptoms could have been attributed to the direct compression of the dolichoectatic OA in the optic canal. A sufficient anastomosis between the central retinal artery and the middle meningeal artery was identified on external carotid angiography with balloon occlusion of the internal carotid artery. Endovascular treatment with internal trapping of the OA was performed due to ophthalmic symptom progression. Internal coil trapping of the OA was performed at the short segment between the OA bifurcation and the entrance of the optic canal. As expected, the central retinal artery was supplied via the middle meningeal artery after the treatment. The transient visual disturbance was immediately resolved. Ophthalmalgia worsened temporarily after the treatment. However, it completely resolved after several days of oral corticosteroid therapy. Postoperative angiography showed that the origin of the OA was occluded and that the OA in the optic canal was shrunk. The flow of the central retinal arteries via the middle meningeal artery was preserved. CONCLUSIONS: OA dolichoectasia is rare, and its pathogenesis and long-term visual prognosis are still unknown. However, endovascular therapy can improve symptom by releasing the pressure site in the optic canal.

Improving the Reachability of Contact Aspiration for Acute Ischemic Stroke Using a New Delivery Assist Catheter.

OBJECTIVE: This study aimed to improve the reachability of large lumen catheter for contact aspiration during acute ischemic stroke by a new delivery assist catheter. METHODS: This study included 58 patients with large-vessel stroke treated using endovascular procedures at our institution and affiliated hospitals between July 2021 and January 2023. Contact aspiration, especially contact aspiration using nonpenetrating of thrombus (CANP) technique, was adopted as first-line thrombectomy for localized internal carotid artery, middle cerebral artery proximal (M1 segment), and basilar artery without tandem occlusion in acute stroke. The new delivery assist catheter (AXS Offset catheter, Stryker, Fremont, CA, USA) was standardized after its release. Results of this improved contact aspiration technique using the new delivery assist catheter, including reachability, procedure time, and first-pass effect, were compared with conventional catheters. RESULTS: Of the 58 patients, 43 underwent only thrombectomy for acute embolic stroke. CANP technique was attempted on 25 patients (25/43, 58.1%). Of these, a normal inner catheter (inner diameter: 0.021 or 0.027 inches) and the new delivery assist catheter were used on 10 (10/25, 40%) and 15 (15/25, 60%) patients, respectively. An aspiration catheter reached the thrombus for 5 patients (5/10, 50%) and 14 patients (14/15 93.3%) in the normal and new delivery assist catheter groups, respectively (P = 0.023). There was no significant difference in the results of contact aspiration due to the delivery catheter. CONCLUSIONS: The new delivery assist catheter improved the reachability of the aspiration catheter to the thrombus and is an effective device for performing CANP technique.

Intraarterial urokinase for thrombus migration after mechanical thrombectomy for large vessel ischemic stroke.

BACKGROUND: Achieving rapid and complete reperfusion is the ultimate purpose for ischemic stroke with large vessel occlusion (LVO). Although mechanical thrombectomy (MT) had been a proverbially important procedure, medium vessel occlusion (MeVO) with thrombus migration can sporadically occur after MT. Moreover, the safe and effective approach for such had been unknown. We reported thrombolysis with intraarterial urokinase for MeVO with thrombus migration after MT. METHODS: We included 122 patients who were treated by MT with LVO stroke at our institution between April 2019 and March 2021. Of 26 patients (21.3%) who developed MeVO with thrombus migration after MT, 11 (9.0%) underwent additional MT (MT group) and 15 (12.3%) received intraarterial urokinase (UK group). The procedure time; angiographically modified Treatment in Cerebral Ischemia Scale (mTICI); functional independence, which was defined as modified Rankin Scale 0-2, on day 30 or upon discharge; and symptomatic and asymptomatic intracerebral hemorrhage (ICH) were compared between the UK and MT groups. RESULTS: The procedure time, mTICI, and asymptomatic ICH did not significantly differ between the groups. In the UK group, 8 of 15 (53.3%) patients obtained functional independence, and the functional independence rate was significantly higher in the UK group than in the MT group (p < 0.05). Symptomatic ICH did not occur in the UK group, and its incidence was significantly smaller than that in the MT group (p < 0.05). CONCLUSION: The results of this study suggest that intraarterial urokinase for MeVO with thrombus migration after MT may safely improve angiographic reperfusion.

De novo dural arteriovenous fistula after mechanical thrombectomy for cerebral venous thrombosis: A case report.

Background: Although the relationship between dural arteriovenous fistula (dAVF) and cerebral venous thrombosis (CVT) has been reported, the etiology has not been clarified. Here, we report a case of de novo dAVF after mechanical thrombectomy for CVT and discuss the underlying mechanism. Case Description: A 61-year-old woman presented with a gradually worsening headache and was diagnosed with severe CVT. Mechanical thrombectomy was performed for the CVT because of progressive neurological deterioration despite anticoagulation therapy. Two years after the initial treatment, angiography revealed a de novo dAVF with a direct shunt of the left convexity cortical vein. Transarterial embolization with Onyx was performed and the shunt was completely obliterated. Conclusion: In this report, we describe a case of de novo dAVF with CVT that was treated with mechanical thrombectomy. Even if CVT improves with mechanical thrombectomy, we must be aware of the occurrence of de novo dAVF.

Familiarization with Contact Aspiration using Non-Penetrating of the Thrombus (CANP) Technique as the Initial Procedure for Acute Ischemic Stroke.

OBJECTIVES: This study aimed to prove the safety and efficacy of the contact aspiration using non-penetrating of thrombus (CANP) technique for the initial procedure for acute ischemic stroke and to increase operator familiarization with the technical aspects of the CANP technique. MATERIALS AND METHODS: A total of 103 patients with large-vessel stroke who were treated using thrombectomy alone at our institution between April 2019 and March 2021 were included in this study. CANP technique was performed using a large lumen catheter (inner diameter, ≥0.060 in.) without penetrating a thrombus. Results of the CANP technique, including the procedure time; first-pass effect (FPE); angiographical recanalization; functional independence; thrombus migration; and intracerebral hemorrhage (ICH) were compared with combined technique. RESULTS: A total of 77 patients (74.8%) were scheduled to undergo the CANP technique for initial procedure, and 50 (64.9%) attempted the CANP technique. Of 50 patients with CANP technique, 33 (66.0%) achieved angiographically good recanalization using CANP technique alone. FPE was achieved in 31 patients (62.0%) in CANP technique group; the rate of FPE was significantly higher (p = 0.008). Asymptomatic ICH were significantly smaller in the CANP technique group (p = 0.008). The median interval of only the CANP technique was 20 (IQR, 16-29.5) min for groin puncture to final recanalization, and was significantly faster (p < 0.001). CONCLUSIONS: CANP technique was safe with low risk of hemorrhagic complication and effective for the initial procedure of acute ischemic stroke.

Use of flexible endoscopic aspiration for an intraventricular small floating clot with hemorrhage: a technical note.

BACKGROUND: Although flexible endoscopy is effective for intraventricular lesions, it is less frequently used for hemorrhagic cases. In some hemorrhagic strokes, blood clots may plunge into the cerebral aqueduct and cause acute obstructive hydrocephalus. A flexible endoscope can aspirate clots and prevent acute hydrocephalus. METHODS: Here, we report four cases of hemorrhage: one of intracerebral hemorrhage and three of subarachnoid hemorrhages. RESULTS: In all cases, acute hydrocephalus was not apparent upon admission. Sudden comatose occurred; computed tomography revealed acute obstructive hydrocephalus with a strangulated clot in the cerebral aqueduct. We performed aspiration of the strangulated clot using a flexible endoscope. Consciousness improved in all cases, and acute hydrocephalus was prevented in all cases. CONCLUSION: The use of simple flexible endoscopic aspiration for clots might be a beneficial and less-invasive procedure for acute obstructive hydrocephalus caused by a small clot with hemorrhagic stroke.

Optimal first coil selection to avoid aneurysmal recanalization in endovascular intracranial aneurysmal coiling.

BACKGROUND: Aneurysmal recanalization is a problem with endovascular coiling and one of its risk factors is the low volume embolization ratio (VER). The first coil VER (1st VER) is believed to be critical for obtaining a high VER. The main objective of this study was to evaluate factors potentially useful for selecting the optimal 1st VER for endovascular coiling. METHODS: 609 initial saccular aneurysmal treatments performed between January 2010 and December 2014 at our institution were included in this retrospective study. Attempted procedures, retreatment cases, intraoperative rupture cases, and stent-assisted coiling cases were excluded. Age, sex, aneurysm location, ruptured aneurysm, aneurysm shape, neck size, maximum aneurysm size, dome-to-neck ratio, aneurysm volume, procedure, immediate Raymond scale score, 1st VER, and VER between the recanalization groups and non-recanalization groups were compared. RESULTS: The factors related to recanalization were ruptured aneurysms, neck width, maximum aneurysm size, aneurysm volume, procedure, 1st VER, and VER. The cut-off values for aneurysm recanalization were a 1st VER of 10.0% and a VER of 33.0%. The maximum average VER of normal size aneurysms was found in the groups with a 1st VER of 17.5-20.0%. CONCLUSIONS: 1st VER was found to be a helpful index for estimating aneurysmal recanalization after coil embolization. The target 1st VER was 17.5-20.0% for obtaining a higher VER and avoiding recanalization.

[Usefulness of Bilateral rSO2 Monitoring for Predicting Cerebral Hyperperfusion Syndrome after Carotid Artery Stenting].

OBJECTIVE: Cerebral hyperperfusion syndrome(CHS)and cerebral hyperperfusion phenomenon(CHP)induce intracranial hemorrhage and can become critical complications after carotid artery stenting(CAS). The purpose of the present study was to predict and avoid CHS after CAS using bilateral rSO2 intraoperative monitoring. METHODS: We retrospectively analyzed 100 consecutive patients who underwent CAS between January 2012 and May 2014 in our institution. We performed continuous bilateral rSO2 monitoring from anesthetic induction to the day following CAS. CHS was defined as the deterioration of neurological conditions post-CAS, no ischemic changes on post-CAS head CT or brain MRI, an increase in cerebral blood flow(CBF)and cerebral blood volume(CBV), and shortening of the mean transit time(MTT)or time to peak(TTP)on CT perfusion. To compare the CHS/CHP group and non-CHS/CHP group, we defined four parameters:rSO2 difference(rSO2 at the endpoint of the procedure-baseline rSO2), ΔrSO2 difference(affected side rSO2 difference-unaffected side rSO2 difference), rSO2 ratio(rSO2 at the endpoint of the procedure/baseline rSO2), and ΔrSO2 ratio(affected side rSO2 ratio/unaffected side rSO2 ratio). RESULTS: There were 2 CHS cases(2.2%)and 3 CHP cases(3.3%). In the CHS/CHP group, the ΔrSO2 difference and ΔrSO2 ratio were significantly higher than those in the non-CHS/CHP group(p value<0.05);however, no significant differences were found in the affected side rSO2 difference(p value=0.063)and affected side rSO2 ratio(p value=0.054)between the groups. CONCLUSION: We could promptly detect CHS and CHP in all cases by using continuous bilateral rSO2 monitoring and analysis of the ΔrSO2 difference and ΔrSO2 ratio.

Altered Expression of MicroRNA-15a and Kruppel-Like Factor 4 in Cerebrospinal Fluid and Plasma After Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND: Cerebral vasospasm (CVS) is a major determinant of prognosis in patients with subarachnoid hemorrhage (SAH). Alteration in the vascular phenotype contributes to development of CVS. However, little is known about the role of microRNAs (miRNAs) in the phenotypic alteration after SAH. We investigated the expression profile of miRNAs and the chronologic changes in the expression of microRNA-15a (miR-15a) and Kruppel-like factor 4 (KLF4), a potent regulator of vascular phenotype modulation that modulates the expression of miR-15a, in the plasma and cerebrospinal fluid (CSF) of patients with SAH. METHODS: Peripheral blood and CSF samples were collected from 8 patients with aneurysmal SAH treated with endovascular obliteration. Samples obtained from 3 patients without SAH were used as controls in the analysis. Exosomal miRNAs were isolated and subjected to microarray analysis with the three-dimensional-gene miRNA microarray kit. The time course of the expression of miR-15a and KLF4 was analyzed using quantitative real-time polymerase chain reaction. RESULTS: Microarray analysis showed that 12 miRNAs including miR-15a were upregulated or downregulated both in the CSF and in plasma after SAH within 3 days. Quantitative real-time polymerase chain reaction showed that miR-15a expression was significantly increased in both the CSF and plasma, with a peak around 3-5 days after SAH, whereas the expression of KLF4 was significantly decreased around 1-3 days after SAH and remained lower than in controls. CONCLUSIONS: Our results suggest that an early and persistent decrease in KLF4 followed by an increase in miR-15a may contribute to the altered vascular phenotype, resulting in development of CVS.

Right persistent trigeminal artery variant (PTAV) and tiny left PTA associated with bilateral ophthalmic arteries arising from the cavernous segments of the internal carotid arteries.

Persistent trigeminal artery (PTA) and its variant (PTAV) are the most prevalent types of carotid-vertebrobasilar anastomosis, but bilateral anastomoses are exceedingly rare. We report a case of a right PTAV and tiny left lateral-type PTA from which the cerebellar artery (presumed anterior inferior cerebellar artery) arose. And also, bilateral ophthalmic arteries arose from the cavernous segments of the internal carotid arteries and entered the orbits via the superior orbital fissures. Selective cerebral angiography, especially 3-dimensional angiography, is superior to magnetic resonance (MR) angiography to identify rare variations of the cerebral arteries. Careful observation of MR angiographic source images is important for identifying unique arterial coursing.

Duplicate origin and extremely long P1 segment of the posterior cerebral artery diagnosed by MR angiography.

We present what we believe is the first report of a patient with an anomalous artery arising from the distal basilar artery and fusing with the mid-portion of an extremely long P1 segment of the left posterior cerebral artery that was diagnosed on magnetic resonance (MR) angiography. Careful review of MR angiographic images is important to detect rare arterial variations, and partial maximum-intensity-projection images aid their identification on MR angiography.

Flow changes in the posterior communicating artery related to flow-diverter stents in carotid siphon aneurysms.

BACKGROUND: Flow-diverter stent (FDS) placement for treatment of intracranial aneurysms can cause flow changes in the covered branches. OBJECTIVE: To assess the impact of the treatment of carotid siphon aneurysms with FDS on the posterior communicating artery (PComA) flow. MATERIALS AND METHODS: Between February 2011 and January 2015, 125 carotid siphon aneurysms were treated with FDS. We retrospectively analyzed all cases with PComA ostial coverage. The circle of Willis anatomy was also studied as the flow changes in PComA postoperatively and during angiographic follow-up. Data from neurological examination were also collected. RESULTS: Eighteen aneurysms of the carotid siphon in 17 patients were treated with FDS covering the ostium of the PComA. Based on the initial angiography, patients were divided into two groups: the first with a P1/PComA size ratio >1 (10 cases) and the second with a ratio ≤1 (8 cases). Follow-up angiography (mean time of 10 months) showed 90% of PComA flow changes in group 1 but only 12.5% in group 2. There was a significant difference between the two groups (p=0.002). Nevertheless, no patient had new symptoms related to these flow changes during the follow-up period. CONCLUSIONS: In our experience, covering the PComA by FDS when treating carotid siphon aneurysms appeared safe and the P1/PComA ratio is a good predictor of flow changes in PComA.

Carotid Artery Stenting for Acute Ischemic Stroke Patients after Intravenous Recombinant Tissue Plasminogen Activator Treatment.

We herein report three ischemic stroke patients who underwent emergency carotid artery stenting after receiving intravenous tissue plasminogen activator (t-PA) treatment. All patients received antiplatelet medications immediately before stent placement for loading as well as dual antiplatelet therapy after stenting. Under high-dose and dual antiplatelet therapy, none of the three patients showed symptomatic intracranial hemorrhaging. However, one case showed reocclusion of the placed stent after acute thrombosis. As a result, new treatment strategies for the use of antiplatelet agents during emergency stent placement must be developed, particularly for patients who have received intravenous t-PA therapy.

True fenestration of the anterior communicating artery diagnosed by magnetic resonance angiography.

Variations of the anterior cerebral artery-anterior communicating artery (ACoA) complex are common. Most are duplicated or partially duplicated ACoAs that are confused with fenestration of the ACoA. We report here an extremely rare case of true fenestration of the ACoA diagnosed by magnetic resonance angiography. Tiny true fenestrations of the ACoA may be overlooked easily by MR angiography. Partial maximum-intensity-projection image and volume-rendering image are useful in identifying true fenestration of the ACoA.

The safety and efficacy of preoperative embolization of meningioma with N-butyl cyanoacrylate.

OBJECTIVE: Preoperative embolization of meningioma is commonly performed; however, there is no consensus on the best embolic material to reduce intraoperative blood loss and surgery time. METHOD: We retrospectively assessed the safety and efficacy of 56 cases of preoperative embolization of the middle meningeal artery with N-butyl cyanoacrylate (NBCA) in 105 cases of surgery for meningioma. We also defined a blood loss to tumor volume ratio to compensate for bias caused by tumor volume, and analyzed limited cases (the embolized group n = 52, the non-embolized group n = 21) of the convexity, the parasagittal region, the falx, and the sphenoidal ridge. RESULT: The blood loss to tumor volume ratio was significantly less in the embolized group (p < 0.007). Preoperative embolization could be useful for cases with the external carotid artery as the dominant feeder vessel (p < 0.02); however, the efficacy decreased for cases with an internal carotid artery feeder. Transient complications occurred in four cases (hemiparesis secondary to edema: two cases; intratumoral bleeding: one case; trigeminal nerve disorder: one case). The cases that showed a postoperative increase in edema or intratumoral bleeding were large tumors with the early filling of veins. For such cases, surgeons should pay close attention to slow injection speed and higher NBCA viscosity, not to cause the occlusion of draining vessels. CONCLUSION: Tumor embolization with NBCA can be safely performed, and the procedure significantly reduces intraoperative blood loss.

Patency of the anterior choroidal artery covered with a flow-diverter stent.

OBJECT: The concept of the flow-diverter stent (FDS) is to induce aneurysmal thrombosis while preserving the patency of the parent vessel and any covered branches. In some circumstances, it is impossible to avoid dangerously covering small branches, such as the anterior choroidal artery (AChA), with the stent. In this paper, the authors describe the clinical and angiographic effects of covering the AChA with an FDS. METHODS: Between April 2011 and July 2013, 92 patients with intracranial aneurysms were treated with the use of FDSs in the authors' institution. For 20 consecutive patients (21.7%) retrospectively included in this study, this involved the unavoidable covering of the AChA with a single FDS during endovascular therapy. AChAs feeding the choroid plexus were classified as the long-course group (14 cases), and those not feeding the choroid plexus were classified as the short-course group (6 cases). Clinical symptoms and the angiographic aspect of the AChA were evaluated immediately after stent delivery and during follow-up. Neurological examinations were performed to rule out hemiparesis, hemihypesthesia, hemianopsia, and other cortical signs. RESULTS: FDS placement had no immediate effect on AChA blood flow. Data were obtained from 1-month clinical follow-up in all patients and from midterm angiographic follow-up in 17 patients (85.0%), with a mean length of 9.8 ± 5.4 months. No patient in either group complained of transient or permanent symptoms related to an AChA occlusion. In all cases, the AChA remained patent without any flow changes. CONCLUSIONS: The results of this study suggest that when impossible to avoid, the AChA may be safely covered with a single FDS during intracranial aneurysm treatment, irrespective of anatomy and anastomoses.

Risk factors for coil protrusion into the parent artery and associated thrombo-embolic events following unruptured cerebral aneurysm embolization.

OBJECTIVE: Advances in vascular reconstruction devices and coil technologies have made coil embolization a popular and effective strategy for treatment of relatively wide-neck cerebral aneurysms. However, coil protrusion occurs occasionally, and little is known about the frequency, the risk factors and the risk of thrombo-embolic complications. METHOD: We assessed the frequency and the risk factors for coil protrusion in 330 unruptured aneurysm embolization cases, and examined the occurrence of cerebral infarction by diffusion-weighted magnetic resonance imaging (DW-MRI). RESULT: Forty-four instances of coil protrusion were encountered during coil embolization (13.3% of cases), but incidence was reduced to 33 (10% of cases) by balloon press or insertion of the next coil. Coil protrusion occurred more frequently during the last phase of the procedure, and both a wide neck (large fundus to neck ratio) (OR = 1.84, P = 0.03) and an inadequately stable neck frame (OR = 5.49, P = 0.0007) increased protrusion risk. Coil protrusions did not increase the incidence of high-intensity lesions (infarcts) on DW-MRI (33.3% vs 29% of cases with no coil protrusion). However, longer operation time did increase infarct risk (P = 0.0003). Thus, tail or loop type coil protrusion did not increase the risk of thrombo-embolic complications, if adequate blood flow was maintained. CONCLUSION: Coil protrusion tended to occur more frequently in cases of wide-neck aneurysms with loose neck framing. Moderate and less coil protrusion carries no additional thrombo-embolic risk, if blood flow is maintained, which can be aided by additional post-operative antiplatelet therapy.