Extracranial Internal Carotid Artery Research Articles

Role of transcranial Doppler ultrasonography in assessing stenosis after flow diversion

IntroductionPatients after implantation of flow diverters (FD) due to intracranial aneurysms require radiological and clinical follow-up in view of in-stent stenosis. The aim of the study was to evaluate transcranial Doppler ultrasonography (TCD) as an alternative to more invasive digital subtraction angiography in monitoring patients with FD. Patients and methodsTwenty-five patients after FD deployment due to internal carotid artery (ICA) aneurysms were reviewed. The degree stenosis found on TCD was compared with the results of catheter angiography. The TCD examinations were recorded from two sides at the extracranial ICA and the most proximal and distal segment of intracranial ICA. Analyzed TCD factors included: peak systolic blood flow velocity, end diastolic velocity, mean velocity, pulsatility index, and resistivity index. The side-to-side differences and ratios between particular TCD indices were calculated. ResultsThe cumulative frequency of angiographic in-stent stenosis was 5 of 25 (20 %). The analysis showed that pulsatility index measured on the most proximal intracranial segment of ICA is a predictor for angiographic instent stenosis (AUC = 0.854; p = 0.04; 95 % CI 0.59–1.00). The threshold of pulsatility index separating stenosis and non-stenosis groups was 1.05 with a sensitivity of 50 % and a specificity of 100 %. As the cut-off threshold of PI was set 0.75 the sensitivity and specificity was 100 % and 16.7 %, respectively. ConclusionsThe increased TCD-derived pulsatility index measured on the most proximal intracranial segment of ICA is associated with in-stent stenosis demonstrated on angiograms.

Sex differences in intracranial and extracranial atherosclerosis in patients with acute ischemic stroke.

Background and aimTo investigate sex differences with respect to presence and location of atherosclerosis in acute ischemic stroke patients.MethodsParticipants with acute ischemic stroke were included from the Dutch acute stroke trial, a large prospective multicenter cohort study performed between May 2009 and August 2013. All patients received computed tomography/computed tomography-angiography within 9 h of stroke onset. We assessed presence of atherosclerosis in the intra- and extracranial internal carotid and vertebrobasilar arteries. In addition, we determined the burden of intracranial atherosclerosis by quantifying internal carotid and vertebrobasilar artery calcifications, resulting in calcium volumes. Prevalence ratios between women and men were calculated with Poisson regression analysis and adjusted prevalence ratio for potential confounders (age, hypertension, hyperlipidemia, diabetes, smoking, and alcohol use).ResultsWe included 1397 patients with a mean age of 67 years, of whom 600 (43%) were women. Presence of atherosclerosis in intracranial vessel segments was found as frequently in women as in men (71% versus 72%, adjusted prevalence ratio 0.95; 95% CI 0.89–1.01). In addition, intracranial calcification volume did not differ between women and men in both intracranial internal carotid (large burden 35% versus 33%, adjusted prevalence ratio 0.93; 95% CI 0.73–1.19) and vertebrobasilar arteries (large burden 26% versus 40%, adjusted prevalence ratio 0.69; 95% CI 0.41–1.12). Extracranial atherosclerosis was less common in women than in men (74% versus 81%, adjusted prevalence ratio 0.86; 95% CI 0.81–0.92).ConclusionsIn patients with acute ischemic stroke the prevalence of intracranial atherosclerosis does not differ between women and men, while extracranial atherosclerosis is less often present in women compared with men.

Semi-automated measurement of vascular tortuosity and its implications for mechanical thrombectomy performance.

Few studies have examined the geometry of endovascular mechanical thrombectomy pathways. Here we examine the tortuosity and angulations of catheter pathways from the aortic arch to the termination of the internal carotid artery (ICA) and its association with thrombectomy performance. We included 100 consecutive anterior circulation large vessel occlusion thrombectomy patients over 12 months. Computed tomography angiograms (CTA) were used for 3D segmentation of catheter pathway from the aortic arch to ICA termination. Tortuosity index (TI) and angulations of the catheter pathway were measured in a semi-automated fashion. TI and angulation degree were compared between sides and correlated with age and procedural measures. We analyzed 188 catheter pathways in 100 patients. Severe angulation (≤ 30°) was present in 5.8% and 39.4% of common carotid artery (CCA) and extracranial ICA segments, respectively. Five pathways (2.6%) had 360° loop. CCA and extracranial ICA tortuosity had a weak but significant correlation with age (r = 0.17, 0.21, p value = 0.05, 0.02 respectively), time from groin puncture to the site of occlusion (r = 0.29, 0.25, p values = 0.008, 0.026 respectively), and fluoroscopy time (r = 0.022, 0.31, p values = 0.016, 0.001 respectively). There was a significant difference in the pattern of angulation (p value = 0.04) and tortuosity between right and left side in CCA segment (TI = 0.20 ± 0.086 vs. 0.15 ± 0.82, p value < 0.001). There was a significant difference in CCA angulation between right and left sides. TI of extracranial CCA and ICA correlated with age and influenced time from groin puncture to the occlusion site and total fluoroscopy time.

Emergency endovascular treatment of cavernous internal carotid artery acute bleeding with flow diverter stent: a single-center experience

Background and objectiveTo describe our single-center experience in the treatment of cavernous internal carotid artery (ICA) acute bleeding with flow diverter stent (FDS), as a single endovascular procedure or combined with an endoscopic endonasal approach.MethodsWe analyze a case series of 5 patients with cavernous ICA acute bleeding, i.e., 3 iatrogenic, 1 post-traumatic, and 1 erosive neoplastic. After an immediate nasal packing to temporarily bleeding control, patients underwent digital subtraction angiography (DSA) to identify the site of the ICA injury. A concomitant balloon occlusion test (BOT) was performed, to exclude post-occlusive ischemic neurological damage. An FDS was placed with parallel intravenous infusion of abciximab in 3 cases and tirofiban in 2 cases. In two patients, an innovative “sandwich technique” combining the endovascular reconstruction with an extracranial intrasphenoidal cavernous ICA resurfacing with autologous flaps or grafts by endoscopic endonasal approach was performed.ResultsNo patient had periprocedural ischemic-hemorrhagic complications. All patients had a regular clinical evolution, without general complications or new onset of focal neurological deficits. No further bleeding occurred in 3 patients, while 2 cases experienced a mild rebleeding in a period ranging from 5 to 15 days after the endovascular procedure. In these two cases, we proceeded with an endoscopic endonasal procedure to resurface the exposed ICA wall in the sphenoid sinus.ConclusionsAlthough the treatment of choice for cavernous ICA acute bleeding remains the occlusion of the injured vessel, in cases of poor hemodynamic compensation at the BTO, the endovascular FDS emergency placement can be effective. A combined endoscopic endonasal technique to support the extracranial side of the vessel using autologous flaps or grafts can be performed to prevent the risk of rebleeding.

Computer Modeling of Clot Retrieval-Circle of Willis.

Endovascular clot retrieval, often referred to as mechanical thrombectomy, has transformed the treatment of patients with ischemic stroke based on an underlying large cerebral vessel occlusion, ranging from the extracranial internal carotid artery (ICA) to the M1 (proximal) segment of the middle cerebral artery (MCA). The aim of this study was to evaluate the effect of a progressive occlusion of the extracranial portion of the ICA on the cerebral blood flow either with a conventional guiding catheter or a balloon-guiding catheter, which enables the operator to completely occlude the parent artery by inflating the balloon around the tip of this type of guiding catheter. We evaluated the impact of flow reduction in the ICA in the setting of ipsilateral MCA occlusion given the different configurations of the circle of Willis (CoW). The computer model of cerebral arteries was based on anatomical works by Rhoton (1) and van der Eecken (2). The interactive experimental results are available on the web at https://gntem3.shinyapps.io/ecrsim. In the setting of left MCA occlusion, compensation from the anterior and posterior communicating artery preserved the flow in the left anterior cerebral artery (ACA) but not the left MCA branches. Under selected CoW configurations, such as classic, missing Acom, or missing A1 segment of the ACA and concurrent right ICA occlusion, there was a progressive decrease of flow in the left ACA to a minimum of 78% when the simulated catheter fully occluded the left ICA. Flow collapsed (<10%) in the left ACA and MCA branches under CoW configurations, such as bilateral fetal PCA. In summary, compensatory flow collapsed under certain clot retrieval scenarios and unusual configurations of CoW.

Bilateral carotid artery dissection due to Eagle syndrome in a patient with vascular Ehlers-Danlos syndrome: a case report

BackgroundPatients with vascular Ehlers-Danlos syndrome (EDS) occasionally suffer from arterial dissection. Eagle syndrome, which is caused by an elongated styloid process and also causes arterial dissection, is difficult to diagnose and could sometimes be overlooked. Little is known of the coexistence of these two diseases, and treatment strategy is not established. Here, we present a case of bilateral internal carotid artery (ICA) dissection due to Eagle syndrome in a patient with vascular EDS.Case presentationA 30-year-old man was admitted to our hospital because of sudden onset of mild sensory disturbance in his left limbs. He had a history of Ehlers-Danlos syndrome (EDS) and also had left cervical internal carotid artery (ICA) dissection 3 years before. Diffusion-weighted imaging showed acute cerebral infarcts in the right hemisphere. Cervical computed tomography angiography (CTA) revealed the right ICA narrowing at the cervical portion in addition to the previous left cervical ICA dissection. Cervical magnetic resonance imaging (MRI) revealed double-lumen and intramural hematoma at the narrowing portion of the right cervical ICA, which indicates arterial dissection. CT also revealed bilateral elongated styloid processes which are close to each side of cervical ICA. We diagnosed him as bilateral ICA dissection due to bilateral Eagle syndrome. Considering vascular complications due to vascular EDS, we performed closer follow-up with transoral carotid ultrasonography (TOCU). In 4 months, his right ICA dissection gradually improved without stroke recurrence or deterioration of dissection.ConclusionsSince patients with vascular EDS easily develop arterial dissection, Eagle syndrome may be overlooked. Clinicians should consider Eagle syndrome in the case of vascular EDS with extracranial ICA dissection and close follow-up should be prioritized in cases of Eagle syndrome with vascular EDS.

Eptifibatide use following emergent carotid stenting in acute anterior circulation ischemic stroke with tandem occlusion

BackgroundEarly revascularization of the extracranial internal carotid artery in acute anterior circulation ischemic stroke (ACIS) is feasible and may improve clinical outcome. When a stent is deployed, antithrombotic agents should be administered peri-procedurally to ensure stent patency. Our institution implemented a protocol for the use of eptifibatide as a means of maintaining stent patency in the treatment of ACIS associated with cervical internal carotid artery occlusion. MethodsOur internal database was queried for patients who received emergent endovascular therapy (ET) for ACIS with stent placement and eptifibatide administration between July 2016 and 2019. ResultsTwenty nine patients met the study criteria. The etiology was large artery atherosclerosis in 26 cases. Two patients had a dissection (7%), and one had a carotid occlusion related to a recent carotid endarterectomy. Mean NIHSS was 14. Sixteen patients received IVrtPA. Extracranial-intracranial tandem occlusion (TO) was present in 21 of cases. All patients received an eptifibatide bolus followed by an infusion for approximately 24 hours post stent deployment. Head CT was obtained prior to initiation of oral dual antiplatelet therapy with aspirin and clopidogrel. Successful recanalization was achieved in all patients with no evidence of downstream embolization. Symptomatic intracerebral hemorrhage occurred in one patient. Stent occlusion occurred in two patients, only one of which was symptomatic. Favorable clinical outcome with mRS ≤ 2 at 3 months was achieved in seventeen patients. ConclusionsThe use of eptifibatide post procedure was associated with low risk of symptomatic intracranial hemorrhage, including in patients treated with rtPA.

Long-Term Mortality After Carotid Stenting

Carotid artery stenting (CAS) is an established procedure for the treatment of atherosclerotic disease affecting the extracranial internal carotid artery. Recent population-based studies have suggested that long-term survival after CAS may be limited, thereby questioning its efficacy in a real-world scenario. We retrospectively reviewed outcomes of patients undergoing CAS for asymptomatic or symptomatic carotid stenosis by a neurosurgeon or interventional neuroradiologist at our institution between 2008 and 2018. Patient and disease characteristics were recorded, as was the incidence of periprocedural and overall ischemia and mortality after CAS. Risk factors for recurrent ischemia and mortality were identified using a Cox proportional hazards model. There were 238 patients who met inclusion criteria. Mean age was 69.7 years and most patients were male (69.7%); 62.2% underwent CAS for symptomatic carotid stenosis. The use of CAS for treatment of asymptomatic stenosis declined over the study period (P= 0.006). Fourteen patients (5.9%) experienced new or recurrent ipsilateral ischemia during follow-up, with 8 (3.4%) experiencing a stroke with permanent neurologic deficit. Fifty-nine patients (24.8%) died during follow-up, with a median time to death of 111.3 months (95% confidence interval [CI], 95.1-133.6) on Kaplan-Meier analysis. Increasing age at time of CAS (unit risk ratio, 1.05; 95% CI, 1.01-1.10; P= 0.011) and comorbid congestive heart failure (risk ratio, 2.40; 95% CI, 1.39-4.13; P= 0.002) were independent risk factors for mortality during follow-up. Unlike population-based studies, our results indicate acceptable long-term survival after CAS in adequately selected patients.

Use of Continuous Infusions of Eptifibatide and Cangrelor in Large Vessel Occlusion Acute Ischemic Stroke After Emergent Carotid Artery Stenting

Placement of carotid stents in the setting of large vessel occlusion (LVO) is sometimes necessary in patients with steno-occlusive disease of the extracranial internal carotid artery (ICA) or ICA dissection. Use of antiplatelet agents is required to prevent in-stent thrombosis; however, after an LVO, a decompressive hemicraniectomy may be necessary. After placement of a carotid stent, a fine balance must be obtained between preventing stent-related thromboembolic complications while also maintaining the possibility of quickly and safely performing a decompressive hemicraniectomy, if indicated. In this case, we discuss the novel use of continuous eptifibatide and cangrelor infusions after carotid stent placement to maintain stent patency, while preserving the option of emergent hemicraniectomy. A 55-year-old man presented with left hemispheric ischemic symptoms due to flow failure from a left ICA dissection. He underwent emergent angiography with angioplasty and stenting of the petrous and ascending cervical segments of the left ICA. The procedure was complicated by an embolization of thrombus to a left middle cerebral artery (MCA) M2 division branch, resulting in an occlusion, which could not be opened. The patient was placed on short acting intravenous antiplatelet agents (eptifibatide infusion for 60 h and cangrelor infusion for 24 h) for prevention of in-stent thrombosis while under close observation for potential neurologic decline and need for decompressive hemicraniectomy. After 84 h of observation, the patient did not experience a decline and the antiplatelet infusions were discontinued after he received aspirin and a loading dose of clopidogrel. Intravenous eptifibatide or cangrelor infusions are short-acting antiplatelet options that can be used in patients with acute ischemic stroke from LVO in the setting of ICA stent placement when there exists a potential for decompressive hemicraniectomy. J Neurol Res. 2020;10(3):99-103 doi: https://doi.org/10.14740/jnr591

Editors' note: Lower carotid revascularization rates after stroke in racial/ethnic minority-serving US hospitals

Using data from the Nationwide Inpatient Sample, Drs. Faigle et al. compared the incidence rates of carotid intervention between hospitals that serve a predominantly white population (<40% racial/ethnic minority prevalence) against hospitals that serve a predominantly minority population (≥40% minority). Even after adjusting for individual self-reported race/ethnicity, insurance provider, hospital characteristics, and patient comorbidities, the investigators observed a significantly lower probability of carotid intervention in minority hospitals (OR 0.81, 95% CI 0.70–0.93). In a continuous model, for every 10% increase in the proportion of minority patients, the odds of carotid treatment fell by 3% (odds ratio [OR] 0.97, 95% confidence interval [CI] 0.94–1.00). Among racial/ethnic groups, blacks seem to be most affected by this disparity in care. In response, Dr. Joshua Willey comments on the overall low rate of predicted carotid revascularization, even among white patients at white-predominant hospitals (<25%), and the potential for classification errors using International Classification of Diseases, Ninth Revision ( ICD-9 ) codes (which may have captured patients with low-grade carotid stenosis and patients with intracranial stenosis—which is known to preferentially affect certain minority groups more so than whites). The authors respond that the ICD-9 inclusion criteria were highly specific to patients with symptomatic, extracranial internal carotid artery stenosis, although they concede some patients may have had <50% stenosis. They reiterate that the novel finding is not the undertreatment of minority groups when treatment is indicated, but that hospitals serving minority communities are less likely to offer this care. Using data from the Nationwide Inpatient Sample, Drs. Faigle et al. compared the incidence rates of carotid intervention between hospitals that serve a predominantly white population (<40% racial/ethnic minority prevalence) against hospitals that serve a predominantly minority population (≥40% minority). Even after adjusting for individual self-reported race/ethnicity, insurance provider, hospital characteristics, and patient comorbidities, the investigators observed a significantly lower probability of carotid intervention in minority hospitals (OR 0.81, 95% CI 0.70–0.93). In a continuous model, for every 10% increase in the proportion of minority patients, the odds of carotid treatment fell by 3% (odds ratio [OR] 0.97, 95% confidence interval [CI] 0.94–1.00). Among racial/ethnic groups, blacks seem to be most affected by this disparity in care. In response, Dr. Joshua Willey comments on the overall low rate of predicted carotid revascularization, even among white patients at white-predominant hospitals (<25%), and the potential for classification errors using International Classification of Diseases, Ninth Revision ( ICD-9 ) codes (which may have captured patients with low-grade carotid stenosis and patients with intracranial stenosis—which is known to preferentially affect certain minority groups more so than whites). The authors respond that the ICD-9 inclusion criteria were highly specific to patients with symptomatic, extracranial internal carotid artery stenosis, although they concede some patients may have had <50% stenosis. They reiterate that the novel finding is not the undertreatment of minority groups when treatment is indicated, but that hospitals serving minority communities are less likely to offer this care.

Neuroangiography: Review of Anatomy, Periprocedural Management, Technique, and Tips.

Neuroangiography (NA) is a minimally invasive procedure used to diagnose patients with neurovascular diseases. Noninvasive imaging has improved dramatically in recent years and is utilized more frequently; however, further evaluation with NA is still required in certain cases. NA indications include intracranial (cerebral aneurysms, arteriovenous malformations, dural arteriovenous fistula, cerebral vasculitis, cerebral vasospasm, ischemic stroke, nontraumatic subarachnoid hemorrhage, intracerebral hemorrhage, Moyamoya, vein of Galen malformation, intracranial tumors, and pseudotumor cerebri) and extracranial (internal and common carotid artery stenosis, vertebral artery stenosis, carotid artery blowout, vertebral artery blowout, epistaxis, oropharyngeal bleeding, and carotid body tumor) pathologies which can help with diagnosis and potential subsequent endovascular treatment. A thorough understanding of normal and variant cervical/cranial vascular anatomy is required. In addition, periprocedural management, catheter technique, equipment needed, and underlying disease pathology are paramount to successful and safe outcomes. This article will review basic neurovascular anatomy, periprocedural management, NA technique, and tips for safe and successful outcomes.

Outcome and effect of endovascular treatment in stroke associated with acute extracranial internal carotid artery occlusion: Single-center experience in Japan

BackgroundPositive data from several randomized controlled trials (RCTs) of endovascular treatment (EVT) for acute ischemic stroke (AIS) patients with anterior circulation large vessel occlusion (ACLVO) have emerged. However, little evidence exists on EVT for acute extracranial internal carotid artery (EC-ICA) occlusion. We therefore analysed the outcome and effect of EVT on AIS due to ACLVO caused by EC-ICA occlusion, including tandem occlusion compared with that caused by pure intracranial artery occlusion. MethodsA total of 135 consecutive AIS patients with ACLVO between July 2014 and December 2017 were identified. We retrospectively analysed the efficacy of EVT for ACLVO after introducing a stent retriever (SR). We classified ACLVO into the following categories: group A, intracranial artery occlusion without EC-ICA occlusion (pure intracranial artery occlusion), and group B, ipsilateral EC-ICA occlusion with/without intracranial artery occlusion. ResultsIn total, 65 patients were enrolled. Group A comprised 71% (46/65) of all cases. No difference was observed in terms of age, National Institute of Health Stroke Scale (NIHSS) score, Alberta Stroke Program Early Computed Tomography Score–Diffusion Weighted imaging (ASPECTS-DWI), several clinical time intervals, rate of successful revascularization (74% versus 84%), and rate of functional independence (42% versus 39%) between groups A and B. In all patients, an ASPECTS-DWI ≥6 and an onset-to-door time ≤6 h were associated with good outcome, whereas intracranial artery occlusion without EC-ICA occlusion (pure intracranial artery occlusion) was not. ConclusionsThe outcomes support the efficacy of EVT in stroke associated with acute EC-ICA occlusion. In the EVT of AIS due to ACLVO, there was no significant difference in the results between ipsilateral EC-ICA occlusion with/without intracranial artery occlusion and intracranial artery occlusion without EC-ICA occlusion (pure intracranial artery occlusion).

Oculomotor Nerve Palsy that Developed after Endovascular Treatment in an Acute Stroke Patient with a Dissecting Occlusion of the Extracranial Internal Carotid Artery

Oculomotor nerve palsy is underrecognized clinical manifestation of extracranial internal carotid artery (ICA) dissection. Herein we report a case of complete oculomotor nerve palsy following endovascular revascularization, which developed in a patient with acute stroke due to extracranial ICA dissecting occlusion. We also discuss about the development mechanism of oculomotor nerve palsy, considering the vascular anatomy and the possibility of periprocedural complications during endovascular treatment.

Holding up under pressure: a complex interplay between cerebral blood flow and ventilatory responses to alterations in carbon dioxide.

Holding up under pressure: a complex interplay between cerebral blood flow and ventilatory responses to alterations in carbon dioxide.

Serum cystatin C is associated with carotid atherosclerosis in patients with acute ischemic stroke.

Accumulating studies have shown that cystatin C may play important roles in the pathogenesis of arteriosclerosis. However, the association between serum cystatin C and the characteristics of carotid plaques has not been elucidated. Furthermore, the diagnostic value of serum cystatin C in carotid stenosis has not been studied. Serum cystatin C in 156 patients with acute ischemic stroke (AIS) in the carotid artery was measured by ELISA. Intima-media thickness (IMT), stenosis of the symptomatic common carotid artery (CCA), extra/intracranial internal carotid artery (ICA) stenosis, and plaque characteristics were measured and recorded. Receiver operating characteristic (ROC) curves were used to assess the diagnostic value of serum cystatin C in carotid stenosis. One hundred fifty-six patients were divided into two groups based on their cystatin C levels. The degree of arteriosclerosis, the severity of plaques, and stenosis of the symptomatic CCA were significantly higher in the patients with high cystatin C levels. In addition, the rate of unstable plaques was significantly higher in those with high cystatin C. Serum cystatin C levels of 1.075 and 1.125mg/L had diagnostic value in distinguishing stenosis of CCA and extracranial ICA, respectively. Higher cystatin C levels were strongly correlated with symptomatic CCA stenosis and the rate of unstable plaques. Analysis of cystatin C levels may be useful for the identification of CCA stenosis and extracranial ICA in patients with AIS.

Impact of Antiplatelet Therapy During Endovascular Therapy for Tandem Occlusions: A Collaborative Pooled Analysis.

Background and Purpose- Antiplatelet agents could be used in the setting of endovascular therapy for tandem occlusions to reduce the risk of de novo intracranial embolic migration, reocclusion of the extracranial internal carotid artery lesion, or in-stent thrombosis in case of carotid stent placement but have to be balanced with the intracerebral hemorrhagic transformation risk. In this study, we aim to investigate the impact of acute antiplatelet therapy administration on outcomes during endovascular therapy for anterior circulation tandem occlusions. Methods- This is a retrospective analysis of a collaborative pooled analysis of 11 prospective databases from the multicenter observational TITAN registry (Thrombectomy in Tandem Lesions). Patients were divided into groups based on the number of antiplatelet administered during endovascular therapy. The primary outcome was favorable outcome, defined as a modified Rankin Scale score of 0 to 2 at 90 days. Results- This study included a total of 369 patients; 145 (39.3%) did not receive any antiplatelet agent and 224 (60.7%) received at least 1 antiplatelet agent during the procedure. Rate of favorable outcome was nonsignificantly higher in patients treated with antiplatelet therapy (58.3%) compared with those treated without antiplatelet (46.0%; adjusted odds ratio, 1.38 [95% CI, 0.78-2.43]; P=0.26). Rate of 90-day mortality was significantly lower in patients treated with antiplatelet therapy (11.2% versus 18.7%; adjusted odds ratio, 0.47 [95% CI, 0.22-0.98]; P=0.042), without increasing the risk of any intracerebral hemorrhage. Successful reperfusion (modified Thrombolysis in Cerebral Ischemia score 2b-3) rate was significantly better in the antiplatelet therapy group (83.9% versus 71.0%; adjusted odds ratio, 1.89 [95% CI, 1.01-3.64]; P=0.045). Conclusions- Administration of antiplatelet therapy during endovascular therapy for anterior circulation tandem occlusions was safe and was associated with a lower 90-day mortality. Optimal antiplatelet therapy remains to be assessed, especially when emergent carotid artery stenting is performed. Further randomized controlled trials are needed.

Abstract TP128: Determinants of Hemorrhagic Transformation After Emergent Extracranial Internal Carotid Artery Stenting for Tandem Occlusions

Background and Purpose: Extracranial internal carotid artery (ICA) lesion in the setting of tandem occlusions is a therapeutic challenge, and hemorrhagic transformation (HT) is one of the leading causes of poor clinical outcome. We aimed to determine determinants of HT for tandem occlusions undergoing emergent extracranial ICA stenting during endovascular treatment (EVT). Methods: We performed a prospective, observational cohort study of consecutive patients with non-cardioembolic ischemic stroke due to tandem occlusion who underwent EVT with extracranial ICA stent placement during the procedure from April 2013 to June 2019 in a single stroke center. We compared clinical (vascular risk factors, previous antiplatelet treatment, and IV rtPA), radiological (ASPECTS at admission and in-stent thrombosis at 24 hours) and serological (platelet count, fibrinogen, total cholesterol, HDL-cholesterol, and LDL-cholesterol) parameters according to the presence of HT in 24 hours CT-scan. Results: One-hundred and eight patients were included: 78.7% were men, mean age 68.5±14.3 years, median time from symptoms onset to treatment was 220 (150-337.5) minutes, median ASPECTS at admission was 9 (8-10). Eighty-six (79.6%) patients presented an extracranial ICA occlusion, and 22 (20.4%) a high-grade (&gt;50%) stenosis. In 88 (81.5%) patients the etiology of extracranial ICA lesion was ateroma, and in 20 (18.5%) was a dissection. Intravenous rtPA was administered in 47 (43.5%) patients. Successful recanalization (mTICI ≥2b) was achieved in 83 (76.9%) patients, and extracranial ICA recanalization in 108 (100%) patients. Type 2 diabetes (OR 1.5, 95% CI 1.1-3.5), higher fibrinogen levels (OR 4.6, 95% CI 1.6-12.9), and ASPECTS &lt;7 at admission (OR 2.1, 95% IC 1.1-5.1) were found as independent predictors of HT in multiple logistic regression analysis. Conclusions: Patients with a non-cardioembolic ischemic stroke due to tandem occlusion who present type 2 diabetes, higher fibrinogen levels, or ASPECTS &lt;7 at admission are at high risk of HT. In these particular cases, it might be useful to stent with a stent that does not need double antiplatelet treatment immediately after the procedure.

Abstract TP205: Association Between Morphological Variations of Extracranial Internal Carotid Artery and Cerebral White Matter Hyperintensities

Background: Cerebral white matter hyperintensities (WMHs) often remain asymptomatic until they widely affect brain structure. The association between small and large vessel diseases is worth studying. We aimed to explore the relationship between morphological variations of extracranial internal carotid artery (EICA) and WMHs. The classic evaluation system of artery variations failed to describe the compound abnormities, and therefore some novel parameters were proposed in this study. Methods: Neck CT angiography scans and brain MRI data of 97 patients with acute ischemic stroke were retrospectively analyzed. The angle of EICA, tortuosity index (TI), deviation degree (DD) and angular number (AN) were measured as parameters of artery morphological variations (Figure). The severity of WMHs was assessed by Fazekas Scale. Differences of vascular morphological variations between mild and severe white matter lesion groups and factors independently associated with WMHs were analyzed. Results: Compared with the patients with mild WMHs, patients with severe WMHs were older ( P =0.001), had higher average systolic blood pressure ( P =0.026), larger median TI ( P &lt;0.001) and median DD ( P &lt;0.001). Also, more patients with severe WMHs had sharp blood vessel angles ( P =0.001) and history of stroke ( P =0.034). Sharp blood vessel angle (OR 4.056, 95%CI 1.578-10.467) and TI (OR 1.037, 95%CI 1.007-1.068) were independently associated with severe WMHs proved by multivariate logistic analysis. Several regression models suggested that age and history of stroke had close relationship with WMHs. Conclusions: Sharp angle of EICA and TI were independently associated with severe WMHs. Besides, age and history of stroke were firmly related to white matter lesions.

Abstract WP57: Acute Carotid Stenting Following Intracranial Thrombectomy Has Comparable Safety and Efficacy in Early versus Late Time Window Stroke

Introduction: Endovascular thrombectomy (EVT) is beneficial in late time window stroke. However, patients with tandem extracranial carotid and intracranial occlusions are under-represented in previous trials. We analysed our acute anterior circulation strokes with tandem occlusions treated with EVT and extracranial internal carotid artery stenting. Methods: A prospectively maintained database of EVT patients treated in two Australian comprehensive stroke centres between January 2016 and May 2019 was screened for acute anterior circulation ischaemic stroke patients treated with EVT and extracranial internal carotid artery stenting. The cohort was divided into patients treated in early ( &lt; 6 hours from symptom onset) and late (&gt;6 hours from symptom onset) time windows. Results: Endovascular thrombectomy with acute carotid stenting was performed in 96 patients (mean age 71years, 78.3% male, mean time to reperfusion 13.5 +/- 10.1 hours, median NIHSS 15). Treatment &gt;6hours after symptom onset occurred in 61 (63.5%) patients. No significant difference was seen between the two groups with respect to age, sex, presenting NIHSS, or mTICI score. At 90-day follow-up, good functional outcome (mRS 0-2) was similar for patients treated in the late versus early time windows, 19 (54.3%) vs 34 (55.7%), p=0.89 respectively. No difference was seen for symptomatic intracranial haemorrhage, 5 (7.2%) vs 3 (8.1%) p=0.87, or mortality at 90-day follow-up, 15 (24.6%) vs 6 (17.1%) p=0.40. Conclusion: Carotid stenting in late time window has comparable safety and efficacy to early time window stroke.

ACOX3 Dysfunction as a Potential Cause of Recurrent Spontaneous Vasospasm of Internal Carotid Artery

Recurrent spontaneous vasospasm of the extracranial internal carotid artery (RSV-eICA) is a rarely recognized cause of ischemic stroke in young adults. However, its pathophysiology remains largely unknown. Through whole-exome sequencing of the ACOX3 gene of two dizygotic Korean twin brothers affected by RSV-eICA, we identified two compound heterozygous missense variants c.235T > G (p.F79V) and c.665G > A (p.G222E). In silico analysis indicated that both variants were classified as pathogenic. In vitro ACOX3 enzyme assay indicated practically no enzyme activity in both F79V and G222E mutants. To determine the effect of the mutants on vasospasm, we used a collagen contraction assay on human aortic smooth muscle cells (HASMC). Carbachol, a cholinergic agonist, induces contraction of HASMC. Knockdown of ACOX3 in HASMC, using siRNA, significantly repressed HASMC contraction triggered by carbachol. The carbachol-induced HASMC contraction was restored by transfection with plasmids encoding siRNA-resistant wild-type ACOX3, but not by transfection with ACOX3 G222E or by co-transfection with ACOX3 F79V and ACOX3 G222E, indicating that the two ACOX3 mutants suppress carbachol-induced HASMC contraction. We propose that an ACOX3 dysfunction elicits a prolonged loss of the basal aortic myogenic tone. As a result, smooth muscles of the ICA's intermediate segment, in which the sympathetic innervation is especially rich, becomes hypersensitive to sympathomimetic stimuli (e.g., heavy exercise) leading to a recurrent vasospasm. Therefore, ACOX3 dysfunction would be a causal mechanism of RSV-eICA. For the first time, we report the possible involvement of ACOX3 in maintaining the basal myogenic tone of human arterial smooth muscle.