Pseudoaneurysm formation and rupture after stereotactic radiotherapy for cerebral arteriovenous malformation: a case report and review of literature.

We report a rare delayed complication of de novo pseudoaneurysm formation and rupture after stereotactic radiotherapy for cerebral arteriovenous malformation. The patient presented with intracerebral haemorrhage due to rupture of a pseudoaneurysm in the previously irradiated field, which was excised for histological examination. The literature was reviewed for similar cases.

Delays in Stroke Onset to Hospital Arrival Time During COVID-19.

BACKGROUND AND PURPOSE: The current coronavirus disease 2019 (COVID-19) pandemic represents a global public health crisis, disrupting emergency healthcare services. We determined whether COVID-19 has resulted in delays in stroke presentation and affected the delivery of acute stroke services in a comprehensive stroke center in Hong Kong. METHODS: We retrospectively reviewed all patients with transient ischemic attack and stroke admitted via the acute stroke pathway of Queen Mary Hospital, Hong Kong, during the first 60 days since the first diagnosed COVID-19 case in Hong Kong (COVID-19: January 23, 2020-March 24, 2020). We compared the stroke onset to hospital arrival (onset-to-door) time and timings of inpatient stroke pathways with patients admitted during the same period in 2019 (pre-COVID-19: January 23, 2019-March 24, 2019). RESULTS: Seventy-three patients in COVID-19 were compared with 89 patients in pre-COVID-19. There were no significant differences in age, sex, vascular risk factors, nor stroke severity between the 2 groups (P>0.05). The median stroke onset-to-door time was ≈1-hour longer in COVID-19 compared with pre-COVID-19 (154 versus 95 minutes, P=0.12), and the proportion of individuals with onset-to-door time within 4.5 hours was significantly lower (55% versus 72%, P=0.024). Significantly fewer cases of transient ischemic attack presented to the hospital during COVID-19 (4% versus 16%, P=0.016), despite no increase in referrals to the transient ischemic attack clinic. Inpatient stroke pathways and treatment time metrics nevertheless did not differ between the 2 groups (P>0.05 for all comparisons). CONCLUSIONS: During the early containment phase of COVID-19, we noted a prolongation in stroke onset to hospital arrival time and a significant reduction in individuals arriving at the hospital within 4.5 hours and presenting with transient ischemic attack. Public education about stroke should continue to be reinforced during the COVID-19 pandemic.

Thrombectomy Outcomes of Intracranial Atherosclerosis-Related Occlusions.

Background and Purpose- Intracranial atherosclerosis (ICAS) is an important cause of large vessel occlusion and poses unique challenges for emergent endovascular thrombectomy. The risk factor profile and therapeutic outcomes of patients with ICAS-related occlusions (ICAS-O) are unclear. We performed a systematic review and meta-analysis of studies reporting the clinical features and thrombectomy outcomes of large vessel occlusion stroke secondary to underlying ICAS (ICAS-O) versus those of other causes (non-ICAS-O). Methods- A literature search on thrombectomy for ICAS-O was performed. Random-effect meta-analysis was used to analyze the prevalence of stroke risk factors and outcomes of thrombectomy between ICAS-O and non-ICAS-O groups. Results- A total of 1967 patients (496 ICAS-O and 1471 non-ICAS-O) were included. The ICAS-O group had significantly higher prevalence of hypertension (odds ratio [OR] 1.46; 95% CI, 1.10-1.93), diabetes mellitus (OR, 1.68; 95% CI, 1.29-2.20), dyslipidemia (OR, 1.94; 95% CI, 1.04-3.62), smoking history (OR, 2.11; 95% CI, 1.40-3.17) but less atrial fibrillation (OR, 0.20; 95% CI, 0.13-0.31) than the non-ICAS-O group. About thrombectomy outcomes, ICAS-O had higher intraprocedural reocclusion rate (OR, 23.7; 95% CI, 6.96-80.7), need for rescue balloon angioplasty (OR, 9.49; 95% CI, 4.11-21.9), rescue intracranial stenting (OR, 14.9; 95% CI, 7.64-29.2), and longer puncture-to-reperfusion time (80.8 versus 55.5 minutes, mean difference 21.3; 95% CI, 11.3-31.3). There was no statistical difference in the rate of final recanalization (modified Thrombolysis in Cerebral Infarction score of 2b/3; OR, 0.67; 95% CI, 0.36-1.27), symptomatic intracerebral hemorrhage (OR, 0.79; 95% CI, 0.50-1.24), good functional outcome (modified Rankin Scale score of 0-2; OR, 1.16; 95% CI, 0.85-1.58), and mortality (OR, 0.94; 95% CI, 0.64-1.39) between ICAS-O and non-ICAS-O. Conclusions- Patients with ICAS-O display a unique risk factor profile and technical challenges for endovascular reperfusion therapy. Intraprocedural reocclusion occurs in one-third of patients with ICAS-O. Intraarterial glycoprotein IIb/IIIa inhibitors infusion, balloon angioplasty, and intracranial stenting may be viable rescue treatment to achieve revascularization, resulting in comparable outcomes to non-ICAS-O.

Age-Specific Associations of Renal Impairment and Cerebral Small Vessel Disease Burden in Chinese with Ischaemic Stroke.

BACKGROUND: Recent studies in Caucasians with transient ischaemic attack or ischaemic stroke have demonstrated significant age-specific associations between cerebral small vessel disease (SVD) burden on magnetic resonance imaging and renal impairment. We aimed to validate these findings in a large cohort of Chinese with ischaemic stroke. METHODS: In 959 Chinese with ischaemic stroke who received a brain magnetic resonance imaging at the University of Hong Kong, we determined the age-specific associations of renal impairment (glomerular filtration rate < 60 mL/min/1.73 m2) with neuroimaging markers of SVD as well as with the SVD score. RESULTS: Although renal impairment was associated with the SVD score in univariate analysis in all patients (odds ratio 1.61, 95% confidence interval 1.24-2.09, P < .0001), these associations were attenuated after adjusting for age and sex (P = .38). Similar findings were noted in patients with ischaemic stroke due to SVD and non-SVD subtypes. However, in 222 of 959 patients aged <60, renal impairment was independently associated with an increasing microbleed (adjusted odds ratio 6.82, 2.26-20.59), subcortical (4.97, 1.62-15.24) periventricular white matter hyperintensity (3.96, 1.08-14.51) and global SVD burden (3.41, 1.16-10.04; all P < .05) even after adjusting for age, sex, and vascular risk factors. Nevertheless, there were no associations between renal impairment and individual neuroimaging markers of SVD nor with the SVD score in patients aged ≥60 after adjusting for age and sex (all P > .05). CONCLUSIONS: In Chinese with ischaemic stroke, renal impairment was independently associated with microbleed, white matter hyperintensity and global SVD burden in individuals aged <60, but not in those aged ≥60, suggesting that there may be shared susceptibilities to premature systemic disease.

Combined aspiration thrombectomy and continuous intrasinus thrombolysis for cerebral venous sinus thrombosis: technical note and case series.

Cerebral venous sinus thrombosis is an uncommon cause of stroke with high morbidity and mortality rates from venous infarction, intracranial hemorrhage, and extensive cerebral edema. Endovascular treatment with various devices has been proposed as a salvage treatment when standard medical treatment with systemic anticoagulation is ineffective, especially in long segment dural sinus thrombosis. We describe our technique of transvenous endovascular aspiration thrombectomy with large bore thrombectomy catheters, followed by placement of microcatheter for local thrombolytic infusion at the site of thrombosis. We report a retrospective study of angiographic and clinical outcome of six consecutive patients treated with this approach. Endovascular aspiration thrombectomy with large bore catheters followed by continuous local thrombolytic infusion appeared to be a safe and effective salvage treatment for selected patients with cerebral dural venous sinus thrombosis refractory to medical treatment.

Computational Fluid Dynamics Study of Bifurcation Aneurysms Treated with Pipeline Embolization Device: Side Branch Diameter Study.

An intracranial aneurysm, abnormal swelling of the cerebral artery, may lead to undesirable rates of mortality and morbidity upon rupture. Endovascular treatment involves the deployment of a flow-diverting stent that covers the aneurysm orifice, thereby reducing the blood flow into the aneurysm and mitigating the risk of rupture. In this study, computational fluid dynamics analysis is performed on a bifurcation model to investigate the change in hemodynamics with various side branch diameters. The condition after the deployment of a pipeline embolization device is also simulated. Hemodynamic factors such as flow velocity, pressure, and wall shear stress are studied. Aneurysms with a larger side branch vessel might have greater risk after treatment in terms of hemodynamics. Although a stent could lead to flow reduction entering the aneurysm, it would drastically alter the flow rate inside the side branch vessel. This may result in side-branch hypoperfusion subsequent to stenting. In addition, two patient-specific bifurcation aneurysms are tested, and the results show good agreement with the idealized models. Furthermore, the peripheral resistance of downstream vessels is investigated by varying the outlet pressure conditions. This quantitative analysis can assist in treatment planning and therapeutic decision-making.

Long non-coding RNA expression profiles predict clinical phenotypes in glioma.

Glioma is the commonest form of primary brain tumor in adults with varying malignancy grades and histological subtypes. Long non-coding RNAs (lncRNAs) are a novel class of non-protein-coding transcripts that have been shown to play important roles in cancer development. To discover novel tumor-related lncRNAs and determine their associations with glioma subtypes, we first applied a lncRNA classification pipeline to identify 1970 lncRNAs that were represented on Affymetrix HG-U133 Plus 2.0 array. We then analyzed the lncRNA expression patterns in a set of previously published glioma gene expression profiles of 268 clinical specimens, and identified sets of lncRNAs that were unique to different histological subtypes (astrocytic versus oligodendroglial tumors) and malignancy grades. These lncRNAs signatures were then subject to validation in another non-overlapping, independent data set that contained 157 glioma samples. This is the first reported study that correlates lncRNA expression profiles with malignancy grade and histological differentiation in human gliomas. Our findings indicate the potential roles of lncRNAs in the biogenesis, development and differentiation of gliomas, and provide an important platform for future studies.

Predictive value of Bispectral Index (BIS) in emergency neurosurgical patients: Loss of BIS reactivity to propofol predicts poor functional outcomes.

AIM: In emergency neurosurgical patients, evaluation with Glasgow Coma Scale (GCS) alone immediately after stopping sedation post-operatively might not differentiate those with good recovery from those with poor outcomes at 3 months. This study aimed to evaluate the prognostic value of measuring the Bispectral Index (BIS) and the correlation to propofol dosage during the use of sedation in the early post-operative period. METHODS: This is a prospective study on consecutive post-operative neurosurgical patients admitted to the neurosurgical ICU on propofol sedation. The primary outcome was the correlation between early post-operative BIS and the Propofol dosage with the modified Rankin scale (mRS) at 3 months. Secondary outcomes included the post-operative propofol requirement in patients with good functional outcomes (mRS 0-3) versus poor functional outcomes (mRS 4-6) at 3 months. RESULTS: In total, 728 BIS readings were collected from twenty-four patients for analysis. The BIS readings were significantly correlated to the propofol dosage in patients with good function outcomes at 3 months (p < 0.0001). BIS readings in patients with no associations to changes in propofol dosage during their ICU stay had poor outcomes (mRS 4-6) at 3 months (r = -0.0407). For patients with good functional outcomes at 3 months, a significantly higher propofol dosage was used for deep sedation (BIS 40 - 60) during the post-operative period (p < 0.001). CONCLUSION: For emergency neurosurgical patients whose BIS readings had lost correlation to the propofol dosage upon recovery, their functional outcomes at 3 months were poor. For those with good functional outcomes at 3 months, a significantly higher propofol dosage was required for deep sedation during their ICU stay. Patients with preserved correlation of BIS readings to changes in propofol dosages during the early post-operative period were associated with good functional outcomes at 3 months.

Surgical revascularization for moyamoya angiopathy: Clinical and radiological outcomes of direct and indirect bypasses in 86 affected hemispheres.

Moyamoya is a progressive cerebral angiopathy that entails a formidable natural history of repeated ischemic or haemorrhagic insults if not intervened. The potential advantages of direct/combined bypass can be harvested only if they are not outweighed by perioperative morbidity. Direct bypasses for the paediatric group have been less utilized because of small vessel calibres and an inherently more robust angioplasticity. This study was undertaken to examine the clinical and perfusion imaging outcomes of operated moyamoya disease or syndrome patients in Hong Kong's Southeast Asian population. Comparison was made between direct/combined and indirect bypass cohorts. Subgroup analysis of the paediatric cohort was conducted to determine outcomes of a direct-bypass-first strategy. From November 2000 to September 2020, 86 hemispheres underwent revascularization at a tertiary neurosurgical unit with a mean clinical follow-up time of 70.0 months. 70.9% of the procedures involved direct bypasses. Direct/combined revascularization demonstrated superiority in restoring adequate cerebrovascular reserve capacity (CVRC) (63.2% vs 27.3%, p = 0.015), and freedom from transient ischemic attacks in the first 5 years post-operation by Kaplan-Meier plot with log-rank test (p = 0.038). Follow-up imaging revealed 96.5% of the bypass grafts remained patent. Direct/combined procedures significantly predicted restoration of adequate CVRC on follow-up perfusions scans by binary logistic regression (OR 4.57, p = 0.009). Compared to the adult cohort, direct bypasses in children carried no excessive perioperative morbidity. These results support a liberal bypass-first paradigm in both adult and paediatric cohorts.

Coincidence of Intracranial Myoepithelioma and Adrenocortical Carcinoma in a Young Man.

Myoepithelial tumors are rare neoplasms that develop from myoepithelial cells in glandular structures and soft tissues. Primary intracranial myoepithelial neoplasms are even rarer with around ten cases reported. On the other hand, adrenocortical carcinoma (ACC) is also uncommon with an annual incidence of 0.7-2 per million and carries a poor prognosis. It is known to have an association with certain familial cancer syndromes. Even in sporadic cases, a significant portion of them had other malignancies before and after diagnosis of ACC. We reported a 34-year-old gentleman who was diagnosed to have ACC without known familial cancer syndrome. After that, he was also found to have right occipital myoepithelioma that was confirmed by excisional biopsy. There was no known association between these two pathologies. This is the first report of coincidence of ACC and intracranial myoepithelioma.

A low-cost and shielding-free ultra-low-field brain MRI scanner.

Magnetic resonance imaging is a key diagnostic tool in modern healthcare, yet it can be cost-prohibitive given the high installation, maintenance and operation costs of the machinery. There are approximately seven scanners per million inhabitants and over 90% are concentrated in high-income countries. We describe an ultra-low-field brain MRI scanner that operates using a standard AC power outlet and is low cost to build. Using a permanent 0.055 Tesla Samarium-cobalt magnet and deep learning for cancellation of electromagnetic interference, it requires neither magnetic nor radiofrequency shielding cages. The scanner is compact, mobile, and acoustically quiet during scanning. We implement four standard clinical neuroimaging protocols (T1- and T2-weighted, fluid-attenuated inversion recovery like, and diffusion-weighted imaging) on this system, and demonstrate preliminary feasibility in diagnosing brain tumor and stroke. Such technology has the potential to meet clinical needs at point of care or in low and middle income countries.

Low-Density Lipoprotein Cholesterol and Risk of Recurrent Vascular Events in Chinese Patients With Ischemic Stroke With and Without Significant Atherosclerosis.

Background Recent trials have shown that low-density lipoprotein cholesterol (LDL-C) <1.80 mmol/L (<70 mg/dL) is associated with a reduced risk of major adverse cardiovascular events in White patients with ischemic stroke with atherosclerosis. However, it remains uncertain whether the findings can be generalized to Asian patients, or that similar LDL-C targets should be adopted in patients with stroke without significant atherosclerosis. Methods and Results We performed a prospective cohort study and recruited consecutive Chinese patients with ischemic stroke with magnetic resonance angiography of the intra- and cervicocranial arteries performed at the University of Hong Kong between 2008 and 2014. Serial postevent LDL-C measurements were obtained. Risk of major adverse cardiovascular events in patients with mean postevent LDL-C <1.80 versus ≥1.80 mmol/L, stratified by presence or absence of significant (≥50%) large-artery disease (LAD) and by ischemic stroke subtypes, were compared. Nine hundred four patients (mean age, 69±12 years; 60% men) were followed up for a mean 6.5±2.4 years (mean, 9±5 LDL-C readings per patient). Regardless of LAD status, patients with a mean postevent LDL-C <1.80 mmol/L were associated with a lower risk of major adverse cardiovascular events (with significant LAD: multivariable-adjusted subdistribution hazard ratio, 0.65; 95% CI, 0.42-0.99; without significant LAD: subdistribution hazard ratio, 0.53; 95% CI, 0.32-0.88) (both P<0.05). Similar findings were noted in patients with ischemic stroke attributable to large-artery atherosclerosis (subdistribution hazard ratio, 0.48; 95% CI, 0.28-0.84) and in patients with other ischemic stroke subtypes (subdistribution hazard ratio, 0.64; 95% CI, 0.43-0.95) (both P<0.05). Conclusions A mean LDL-C <1.80 mmol/L was associated with a lower risk of major adverse cardiovascular events in Chinese patients with ischemic stroke with and without significant LAD. Further randomized trials to determine the optimal LDL-C cutoff in stroke patients without significant atherosclerosis are warranted.

Craniocervical Junction Vertebral Artery Dural Arteriovenous Fistula With Cranial and Spinal Venous Reflux: 2-Dimensional Operative Video.

Dural arteriovenous fistulae at the craniocervical junction are rare. When present together with spinal and cranial venous reflux they can have an aggressive natural history with hemorrhage or progressive myelopathy from venous congestion. In this operative video we demonstrate key steps in the surgical ligation of a dural arteriovenous fistula supplied by meningeal branches of the V4 segment of the vertebral artery. Informed consent was obtained. The patient was positioned prone with chin tucked. Utilizing a midline suboccipital craniotomy and removal of the arch of C1, the vertebral artery was identified at its V4 segment at it transitions from extra to intradural. The video illustrates how a midline approach can be used to access this lesion and a far lateral approach is not required to access the vertebral artery and its dural branches at the craniocervical junction. Division of the denticulate ligaments and mobilization of the spinal accessory nerve allows visualization of the proximal portion of the draining vein. Important anatomy in this region is demonstrated. The critical use of indocyanine green (ICG) dye is demonstrated as the first 2 clip applications were not proximal enough to obliterate the proximal draining vein and persistent early venous reflux was still seen on ICG. The importance of access to and obliteration of the proximal draining vein is shown. An intraoperative ICG and postoperative angiogram demonstrates complete occlusion of the dural arteriovenous fistula. In this case the patient had minor sensory deficits postoperatively which were resolved by 6 wk postoperatively.

Overview of endovascular thrombectomy accessibility gap for acute ischemic stroke in Asia: A multi-national survey.

Endovascular thrombectomy revolutionized the treatment of acute ischemic stroke. Nevertheless, access to endovascular thrombectomy is limited in many parts of the world. Asia holds 60% of the world's population and its countries carry some of the highest stroke disease burden. To understand the availability of endovascular thrombectomy and intravenous thrombolysis in this region, we interviewed stroke neurologists and neuro-interventionists of 19 Asian countries, and found a large disparity in access to endovascular thrombectomy and intravenous thrombolysis between high- and low-income countries. Lack of neuro-interventionists, comprehensive stroke units, stroke triage systems and high treatment cost are the major obstacles to wider accessibility of endovascular thrombectomy, especially among developing countries. The potential solutions to provide equitable access to stroke revascularization therapy are discussed.

Endovascular Intervention for Early Postoperative Stenosis of Extracranial-Intracranial Bypass Graft: Case Report and Review of the Literature.

BACKGROUND: Bypass graft stenosis following extracranial-intracranial bypass surgery carries significant risks for morbidity and mortality. In case of graft failure, treatment options include surgical revision and endovascular intervention. Whereas endovascular intervention following coronary artery bypass is well established, the role of endovascular therapy in cerebral bypass conduits is rarely reported. We present a case of extracranial-intracranial bypass graft stenosis in the early postoperative period that was successfully treated by endovascular angioplasty and stenting. CASE DESCRIPTION: A middle-aged patient presented with a malignant skull base tumor with internal carotid artery invasion. Extracranial-intracranial bypass surgery was performed for flow preservation before tumor removal. Autologous radial artery was used as the bypass graft conduit. Symptomatic graft stenosis was encountered in the immediate postoperative period. Treatments in the form of intra-arterial vasodilator infusion and balloon angioplasty led to only minor flow improvement. The narrowing was eventually salvaged by endovascular stenting. Good clinical and radiologic outcomes were achieved at 6-month follow-up. CONCLUSIONS: Endovascular intervention is a feasible treatment option in management of graft stenosis after cerebral revascularization surgery. Our case adds evidence to the safety and role of endovascular intervention in early cerebral bypass conduit failure. In addition, endovascular stenting can be considered as a salvage option for cases that are refractory to angioplasty.

Near-complete regression 19 years after Gamma Knife radiosurgery of vestibular schwannoma with massive pseudoprogression: case report.

Gamma Knife radiosurgery (GKRS) is a frequent treatment choice for patients with small- to moderate-sized vestibular schwannoma (VS). However, pseudoprogression after GKRS is commonly observed, with a reported incidence ranging from 7% to 77%. The wide range of the reported incidence of pseudoprogression reflects the fact that there is no consensus on how it should be diagnosed. The authors present the case of a 66-year-old woman who had a 2.5-cm right-sided VS treated with GKRS in 1997. The first posttreatment MRI obtained 5 months later showed that the tumor volume had increased to 9.7 cm3. The tumor volume increased further and reached its peak 24 months after treatment at 20.9 cm3, which was a 161% increase from pretreatment volume. Thereafter, the tumor shrank gradually and mass effect on the brainstem reduced over time. By 229 months after treatment, the tumor volume was 1.0 cm3, equaling 12.5% of pretreatment tumor volume, or 4.8% of peak tumor volume after treatment. This case demonstrates that if a patient remains asymptomatic despite a dramatic increase in tumor volume after GKRS, observation remains an option, because even a very sizable tumor can shrink with near-complete resolution. Patients undergoing GKRS for VS should be counseled regarding the possibility of pseudoprogression, and followed carefully over time while avoiding premature decisions for surgical removal after treatment.

Intracranial Atherosclerotic Stenoses: Pathophysiology, Epidemiology, Risk Factors and Current Therapy Options.

Intracranial atherosclerotic stenoses (ICAS) are one of the most common causes of first and recurrent cerebrovascular ischaemic events worldwide, with highest prevalence in Asian, Hispanic and African populations. Clinical trials have improved the understanding of epidemiology, risk factors and imaging characteristics of patients with ICAS. Current therapeutic approaches concerning these patients include management of risk factors, best medical therapy, potentially endovascular and rarely surgical therapy. In our review, we elucidate the current epidemiology and evidence in evaluation of risk factors and therapeutic options for providing favourable outcome for patients with ICAS.

Calcified vessels in the brain are one of the most common causes of first or recurrent ischaemic stroke or transient ischaemic attack worldwide, with highest occurrence in Asian, Hispanic and African populations. Clinical trials have improved the understanding of this particular disease. Current therapy includes management of risk factors, best medical therapy, potentially therapy with a wire and rarely surgical therapy. In our review, we elucidate current knowledge and recommendations.