Ichiro Nakahara

Platelet reactivity and hemorrhage risk in neurointerventional procedures under dual antiplatelet therapy

Background and purpose Hemorrhagic complications during neurointerventional procedures have various etiologies and can result in severe morbidity and mortality. This study investigated the possible association between low platelet reactivity measured by the VerifyNow assay and increased hemorrhagic complications during elective neurointervention under dual antiplatelet therapy. Methods From May 2010 to April 2013 we recorded baseline characteristics, P2Y12 reaction units (PRU), and aspirin reaction units using VerifyNow. The primary endpoint was post-procedural hemorrhagic complications. Results A total of 279 patients were enrolled and 31 major hemorrhagic complications (11.1%) were identified. From receiver-operating characteristic curve analysis, PRU values could discriminate between patients with and without major hemorrhagic complications (area under the curve 0.63). Aspirin reaction unit values had no association with the primary outcome. The optimal cut-off for the primary outcome (PRU ≤175) was used to identify the low platelet reactivity group. The incidence of hemorrhagic complications was 20.0% in this group and 8.9% in the non-low platelet reactivity group. Multivariate analysis identified low platelet reactivity as an independent predictor for hemorrhagic complications. Conclusions The risk of hemorrhagic complications during elective neurointervention including cerebral aneurysm coil embolization and carotid artery stenting under dual antiplatelet therapy is associated with the response to clopidogrel but not to aspirin. A PRU value of ≤175 discriminates between patients with and without hemorrhagic complications. Future prospective studies are required to validate whether a specific PRU value around 170–180 is predictive of hemorrhagic complications.

Prediction of Cerebral Hyperperfusion After Carotid Artery Stenting by Cerebral Angiography and Single-Photon Emission Computed Tomography Without Acetazolamide Challenge

BACKGROUND: Definitive preoperative predictors of cerebral hyperperfusion following carotid artery stenting are yet to be established. OBJECTIVE: To determine the preprocedural risk factors for cerebral hyperperfusion phenomenon (CHP) following carotid artery stenting. METHODS: Patients undergoing preprocedural single‐photon emission computed tomography (SPECT) and cerebral angiography prior to their first carotid artery stenting were monitored for occurrence of CHP. In addition to patient characteristics, we investigated imaging parameters, such as cerebral blood flow, cerebral vasoreactivity, and asymmetry index on SPECT, and presence of near occlusion and leptomeningeal anastomosis on cerebral angiography. RESULTS: Out of 100 patients (mean age: 73.0 ± 7.6 years; 85 men), 9 developed CHP. On multivariate logistic regression analysis, asymmetry index (%) on SPECT (odds ratio [OR] 0.81, 95% confidence interval [CI] 0.70–0.93, P = .003) and presence of leptomeningeal anastomosis on cerebral angiography (OR 72.1, 95% CI 3.52–1480, P = .006) were independent predictors of CHP. CONCLUSION: Combined use of cerebral angiography and SPECT may obviate the need for acetazolamide challenge to predict the risk of CHP following carotid artery stenting.

Dural arteriovenous fistula of the craniocervical junction manifesting as cerebellar haemorrhage.

We report a rare case of dural arteriovenous fistula at the craniocervical junction manifesting as cerebellar haemorrhage, which posed a diagnostic challenge for physicians. A 77-year-old woman with no history of arterial hypertension presented to our Emergency Department with dizziness, and imaging studies revealed a small cerebellar haemorrhage. She was diagnosed with hypertensive intracerebral haemorrhage and conservatively treated. Four months later, she developed subarachnoid haemorrhage, and imaging studies revealed dural arteriovenous fistula at the left C1 dural sleeve. Disruption of a distended cerebellar vein due to venous hypertension by dural arteriovenous fistula was considered to be responsible for intracerebral haemorrhage and subarachnoid haemorrhage. Dural arteriovenous fistula was cured following surgical ligation of a feeding artery and a draining vein. The present case was educational in that effort to identify the cause of bleeding using vascular imaging studies may be important in patients with seemingly typical hypertensive intracerebral haemorrhage, particularly in those without a past history of arterial hypertension.

Improvement in patient outcomes following endovascular treatment of WFNS grade V subarachnoid haemorrhage from 2000 to 2014

Patient outcomes following grade V subarachnoid haemorrhage (SAH) have been dismal, although they may have improved following recent technological advances in endovascular treatment (EVT). A single-centre, retrospective study was conducted to evaluate whether outcomes have improved from 2000 to 2014 for patients with World Federation of Neurosurgical Societies (WFNS) grade V SAH. Coiling has been the preferred first-line treatment for grade V SAH patients in our institution since 2000. Patients who underwent EVT (n=115) were grouped on the basis of their hospital admission year: 2000-2004 (n=44), 2005-2009 (n=37) and 2010-2014 (n=34). Patient demographics, outcomes and in-hospital mortality rates were compared between the groups. Patient outcomes at discharge were evaluated using the Glasgow Outcome Scale (GOS), with GOS scores of 4-5 defined as favourable outcomes. There were no significant intergroup differences in patient demographics. In addition, there were no significant differences in the frequencies of favourable outcomes (14% in 2000-2004, 16% in 2005-2009 and 26% in 2010-2014). Mortality rates were 52% in 2000-2004, 43% in 2005-2009 and 24% in 2010-2014, with a significantly lower mortality rate in 2010-2014 than in 2000-2004 (p=0.01). Both perioperative rebleeding and delayed cerebral ischaemia decreased over time; however, multivariate regression analysis showed that the former contributed more to the decrease in mortality. Age was the only variable associated with favourable outcomes. The results of this study indicate that EVT is an appropriate therapeutic option for grade V SAH patients. However, multi-centre, prospective trials are required to provide evidence-based verification of the efficacy of EVT.

Large Residual Volume, Not Low Packing Density, Is the Most Influential Risk Factor for Recanalization after Coil Embolization of Cerebral Aneurysms.

Background Tight coil packing with density of at least 20%–25% is known to be important for preventing recanalization after embolization of cerebral aneurysms. However, large aneurysms sometimes recanalize regardless of the packing density, suggesting that the absolute residual volume which is determined by aneurysm volume and packing density may be more important risk factor for recanalization. To validate this hypothesis, we analyzed the factors affecting the outcomes of treated aneurysms at our institute. Methods and Findings We included 355 small and large aneurysms. The following six factors were obtained from every case: aneurysm volume (mL), neck size (mm), packing density (%), residual volume (mL), rupture status at presentation, and stent assistance (with or without stent). The data were then subjected to multivariate logistic regression analysis to identify significant risk factors for recanalization. Recanalization occurred in 61 aneurysms (17.2%). Significant predictors for recanalization were aneurysm volume (odds ratio, 15.3; P < 0.001) and residual volume (odds ratio, 30.9; P < 0.001), but not packing density (odds ratio, 0.98; P = 0.341). These results showed that for each 0.1-mL increase in aneurysm volume and residual volume, the risk of recanalization increased by 1.3 times and 1.4 times, respectively. Conclusions The most influential risk factor for recanalization after coil embolization was residual volume, not packing density. The larger the aneurysm volume, the greater the packing density has to be to minimize the residual volume and risk of recanalization. Since tight coil packing has already been aimed, further innovation of coil property or embolization technique may be needed. Otherwise, different treatment modality such as flow diverter or parent artery occlusion may have to be considered.

Improving treatment times for patients with in-hospital stroke using a standardized protocol

BACKGROUND Previous reports have shown significant delays in treatment of in-hospital stroke (IHS). We developed and implemented our IHS alert protocol in April 2014. We aimed to determine the influence of implementation of our IHS alert protocol. METHODS Our implementation processes comprise the following four main steps: IHS protocol development, workshops for hospital staff to learn about the protocol, preparation of standardized IHS treatment kits, and obtaining feedback in a monthly hospital staff conference. We retrospectively compared protocol metrics and clinical outcomes of patients with IHS treated with intravenous thrombolysis and/or endovascular therapy between before (January 2008-March 2014) and after implementation (April 2014-December 2016). RESULTS Fifty-five patients were included (pre, 25; post, 30). After the implementation, significant reductions occurred in the median time from stroke recognition to evaluation by a neurologist (30 vs. 13.5min, p<0.01) and to first neuroimaging (50 vs. 26.5min, p<0.01) and in the median time from first neuroimaging to intravenous thrombolysis (45 vs. 16min, p=0.02). The median time from first neuroimaging to endovascular therapy had a tendency to decrease (75 vs. 53min, p=0.08). There were no differences in the favorable outcomes (modified Rankin scale score of 0-2) at discharge or the incidence of symptomatic intracranial hemorrhage between the two periods. CONCLUSION Our IHS alert protocol implementation saved time in treating patients with IHS without compromising safety.

Noninvasive Assessment of Stenotic Severity and Plaque Characteristics by Coronary CT Angiography in Patients Scheduled for Carotid Artery Revascularization

Aims: Coronary artery atherosclerosis in patients needing carotid revascularization has not been fully clarified. The aim of this study was to evaluate the stenotic severity and plaque characteristics of coronary arteries by coronary computed tomography angiography (CTA) in patients scheduled for carotid-artery stenting (CAS) or carotid endarterectomy (CEA). Methods: We performed coronary CTA after carotid ultrasound (US) in 164 patients (81.7% male, aged 68.1 ± 12.2 years) from 2014 to 2016. Of all, 70 were scheduled for CAS or CEA (CAS/CEA group) and 94 were not (non-CAS/CEA group). Carotid US and coronary CTA were compared for the evaluation of stenotic severity and plaque characteristics of each vessel between CAS/CEA and non-CAS/CEA groups. Results: Between the two groups, there were significant differences in the presence of significant stenosis (SS: ≥ 70% stenosis of coronary artery) (55.7% vs. 39.4%, P = 0.038), triple-vessel disease (TVD)/left main trunk (LMT) (SS in each of three epicardial vessels and/or LMT) (24.3% vs. 7.5%, P = 0.0025), and high-risk plaque (HRP: positive remodeling and/or low attenuation) (55.7% vs. 24.5%, P < 0.0001). CAS/CEA was independently associated with TVD/LMT (OR = 2.30, 95%CI: 1.14–8.59, P = 0.026) and HRP (OR = 3.17, 95%CI: 1.57–6.54, P = 0.0012) in multivariable logistic regression analysis. Similarly, vulnerable plaque (78.6% vs. 2.1%, P < 0.0001) as well as severe stenosis of carotid artery (98.6% vs. 0%, P < 0.0001) was seen more often in CAS/CEA than in non-CAS/CEA group. Conclusions: The prevalence of TVD/LMT and HRP determined by coronary CTA is higher in patients needing CAS/CEA than in those without. Management of systemic atherosclerosis is required in the perioperative period of CAS/CEA.

Dural arteriovenous fistula presenting with acute subdural haematoma showing impending cerebral herniation

A dural arteriovenous fistula (DAVF) presenting with acute subdural haematoma (ASDH), which were not related to head injury, is rare. A 61-year-old woman was transported by ambulance because of deterioration of consciousness. On admission, she was comatose with anisocoria. Emergent CT demonstrated a severe midline shift associated with a left ASDH and an additional left occipital intracerebral haematoma, both of which had no continuity with each other. MRI showed flow void signs in the left occipital lobe. Because of the impending cerebral herniation, an emergent evacuation of the ASDH and external decompression was performed. Subsequent evaluation revealed a DAVF at the left occipital convexity near the confluence with retrograde leptomeningeal venous reflux and venous ectasia (Cognard type III DAVF). The patient underwent endovascular treatment for the DAVF involving transarterial embolisation using coils and N-butyl cyanoacrylate with complete obliteration. Her further clinical course was uneventful and discharged after cranioplasty.

Delayed leucoencephalopathy after coil embolisation of unruptured cerebral aneurysm

A 56-year-old right-handed woman was successfully treated by coil embolisation for a large unruptured paraclinoid aneurysm of the left internal carotid artery. Though she was discharged on day 3 after the intervention with uneventful clinical course, she was rehospitalised for continuous headache and right upper limb weakness 2 weeks after the treatment. Subsequent progression of cognitive dysfunction and right hemiparesis were observed. Repeated MRI revealed diffuse leucoencephalopathy within the ipsilateral brain hemisphere. Clinical course, serological examination, and radiological findings were consistent with localised hypocomplemental vasculitis caused by delayed hypersensitivity reaction. Immunosuppressive treatments using prednisolone successfully improved her symptoms. After a washout period for immunosuppressant, skin reaction test was performed and revealed polyglycolic-polylactic acid, coating material of the coil, positive for delayed allergic reaction. Given the increased frequency of endovascular treatment for unruptured aneurysms, even such a rare complication should be recognised and treated properly to avoid neurological sequelae.

Carotid stenting for unilateral stenosis can increase contralateral hemispheric cerebral blood flow

Background The revascularization of carotid stenosis can increase ipsilateral cerebral blood flow (CBF). Occasionally, elevated CBF is also evident on the contralateral side, but this phenomenon is poorly understood. Objective To analyze retrospectively the relationship between a contralateral CBF increase and several clinical and radiologic features. Materials and methods We retrospectively analyzed 40 patients with unilateral cervical carotid stenosis treated by carotid artery stenting (CAS). Using 123I-iodamphetamine single-photon emission computed tomography (SPECT); we compared pre- and postoperative hemispheric CBF on both sides. We investigated the influence of the following five factors on the increase of the contralateral hemispheric CBF: stenosis grade (≥50% or <50%, according to the North American Symptomatic Carotid Endarterectomy Trial criteria); age; the presence of anterior and posterior communicating arteries; postoperative hyperperfusion on the stenotic side; and the presence of cerebral steal phenomenon during preoperative acetazolamide-challenge SPECT. Results Following unilateral CAS, mean hemispheric CBF increased significantly on both sides: from 33.4±5.6 (mean ± SD) to 38.7±7.8 mL/min on the operated side (paired t test, p<0.001) and f35.4±5.4 to 39.2±7.2 mL/min on the contralateral side (p<0.001). In a general linear model, stenosis grade (≥50%) alone was significantly correlated with the increase of the CBF on the contralateral side (p=0.03). Conclusion Revascularization by CAS for unilateral carotid stenosis can increase hemispheric CBF on both sides. Increase of the contralateral CBF is correlated with stenosis grade (≥50%).